Rev. 1.3 8/06 Copyright © 2006 by Silico n Laboratories Si2400
Si2400
V.22BIS ISOMODEM® WITH INTEGRATED GLOBAL DAA
Features
Applications
Description
The Si2400 ISOmodem® is a complete modem chipset with integrated
direct access arrangement (DAA) that provides a programmable line
interface to meet global telephone line requirements. Available in two 16-
pin small outline (SOIC) packages, it eliminates the need for a separate
DSP data pump, modem controller, analog front end (AFE), isolation
transformer, relays, opto-isolators, 2- to 4-wire hybrid, and voice codec.
The Si2400 is ideal for embedded modem applications due to its small
board space, low power consumption, and global compliance.
Functional Block Diagram
Data Modem Formats
z 2400 bps: V.22bis
z 1200 bps: V.22, V.23, Bell 212A
z 300 bps: V.21, Bell 103
z Fast Connect and V.23 Reversing
z SIA and other security protocols
Caller ID Detection and Decode
DTMF Tone Gen./Detection
3.3 V or 5.0 V Power
UART with Flow Control
Integrated DAA
z Capacitive Isolation
z Parallel Phone Detect
z Globally Compliant Line Interface
z Overcurrent Detection
AT Command Set Support
Integrated Voice Codec
PCM Data Pass-Through Mode
HDLC Framing in Hardware
Call Progress Support
Pb-Free/RoHS-Compliant
Packages Available
Set Top Boxes
Power Meters
Security Systems
ATM Terminals
Medical Monitoring
Point-of-Sale
MUX
UART
μ Co ntro ller
(AT Decoder
Ca ll Pro g ress )
Isolation Interface
Control
Interface
Clock
Interface
DSP
(Da ta Pu mp )
Audio
Codec
Isolation Interface
Hybrid
and
DC
Termination
Ri ng Detect
Off-Hook
RXD
TXD
RESET
EOFR/GPIO1
ESC/GPIO3
CD/AIN/GPIO2
ALERT/GPIO4
CLKOUT
XTALO
XTALI
FILT
FILT2
REF
DCT
VREG2
REXT
REXT2
RNG1
RNG2
QB
QE
QE2
RX
AOUT
Si2400 Si3015
CTS
VREG
Patents pending
Ordering Information
See page 90.
Pin Assignments
Si2400
Si3015
1
2
3
4
5
6
7
89
10
11
12
13
16
15
14
XTALI
XTALO
CLKOUT
VD
RXD*
TXD*
CTS
RESET
EOFR/GPIO1
CD/AIN/GPIO2
ESC/GPIO3
ISOB
GND
C1A
ALERT/GPIO4
AOUT
1
2
3
4
5
6
7
89
10
11
12
13
16
15
14
QE2
DCT
IGND
C1B
RNG1
RNG2
QB
QE
FILT2
FILT
RX
REXT
REXT2
REF
VREG2
VREG
Si2400
Si3015
Si2400
2 Rev. 1.3
Si2400
Rev. 1.3 3
TABLE OF CONTENTS
Section Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4. Analog Input/Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
5. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
5.1. Digital Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
5.2. Configurations and Data Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
5.3. Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.4. Global DAA Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.5. Parallel Phone Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.6. Loop Current Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.7. Carrier Detect/Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.8. Overcurrent Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.9. Caller ID Decoding Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5.10. Tone Generation and Tone Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.11. PCM Data Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.12. Analog Codec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.13. V.23 Operation/V.23 Reversing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.14. V.42 HDLC Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.15. Fast Connect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
5.16. Clock Generation Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
6. AT Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.1. Command Line Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.2. < CR > End Of Line Character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.3. AT Command Set Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
6.4. S-Register Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6.5. Alarm Industry AT Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
6.6. Modem Result Codes and Call Progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
7. Low Level DSP Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
7.1. DSP Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
7.2. Call Progress Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
8. S Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Appendix A—DAA Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
Appendix B—Typical Modem Applications Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . .84
Appendix C—UL1950 3rd Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
9. Pin Descriptions: Si2400 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
10. Pin Descriptions: Si3015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
11. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
12. Package Outline: 16-Pin SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
Si2400
4 Rev. 1.3
1. Electrical Specifications
Table 1. Recommended Operating Conditions
Parameter1Symbol Test Condition Min2Typ Max2Unit
Ambient Temperature TAK-Grade 0 25 70 °C
Ambient Temperature TAB-Grade –40 25 85 °C
Si2400 Supply Voltage, Digital3VD3.0 3.3/5.0 5.25 V
Notes:
1.
The Si2400 specifications are guaranteed when the typical application circuit (including component tolerance) and any
Si2400 and any Si3015 are used. See Figure 3 on page 10 for a typical application circuit.
2.
All minimum a nd maximum specifications are guaranteed and apply across the recommended operating conditions. T ypical
values apply at nominal supply voltages an d an operating temperature of 25 °C unless otherwise stated.
3.
The digital supply, V
D
, can operate from either 3.3 V or 5.0 V. The Si2400 interface supports 3.3 V logic when operating
from 3.3 V. The 3.3 V operation applies to both the serial port and the digital signals CTS, CLKOUT, GPIO1–4, and RESET.
Si2400
Rev. 1.3 5
Table 2. Loop Characteristics
(VD = 3.0 to 5.25 V, TA = 0 to 70°C for K-Grade and –40 to 85°C for B-Grade, See Figure 1)
Parameter Symbol Test Condition Min Typ Max Unit
DC Termination Voltage VTR IL=20 mA, ACT
1=1
b
DCT = 11b (CTR21) ——7.5V
DC Termination Voltage VTR IL=42 mA, ACT=1
b
DCT = 11b (CTR21) ——14.5V
DC Termination Voltage VTR IL=50 mA, ACT=1
b
DCT = 11b (CTR21) ——40 V
DC Termination Voltage VTR IL=60 mA, ACT=1
b
DCT = 11b (CTR21) 40 — — V
DC Termination Voltage VTR IL=20 mA, ACT=0
b
DCT = 01b (Japan) ——6.0V
DC Termination Voltage VTR IL=100 mA, ACT=0
b
DCT = 01b (Japan) 9——V
DC Termination Voltage VTR IL=20 mA, ACT=0
b
DCT = 10b (FCC) ——7.5V
DC Termination Voltage VTR IL=100 mA, ACT=0
b
DCT = 10b (FCC) 9——V
DC Termination Voltage VTR IL=15 mA, ACT=0
b
DCT = 00b
(Low Voltage)
——5.2V
On Hook Leakage Current2ILK VTR = –48V — — 7 µA
Operating Loop Current ILP FCC/Jap an Modes 13 — 120 mA
Operating Loop Current ILP CTR21 Mode 13 — 60 mA
DC Ring Current2DC current flowing
through ring detection
circuitry
—— 7 µA
Ring Detect Voltage3VRD RT = 0b11 — 22 VRMS
Ring Detect Voltage3VRD RT = 1b17 — 33 VRMS
Ring Frequency4FR15 — 68 Hz
Ringer Equivalence Number5REN — — 0.2
Notes:
1. SF[4] (ACT); SF5[3:2] (DCT); SF5[0] (RT).
2. R25 and R26 installed.
3. The ring signal is guaranteed to not be detected below the minimum. The ring signal is guaranteed to be detected
above the maximum.
4. The Si2400 ring detector can be programmed to detect rings between this range.
5. C15, R14, Z2, and Z3 not installed. SF5[1] (RZ) = 0b. See "Ringer Impedance" on page 80.
Si2400
6 Rev. 1.3
Table 3. DC Characteristics1
(VD=4.75 to 5.25 V, TA=0 to 70°C for K-Grade, TA=–40 to 85°C for B-Grade)
Parameter Symbol Test Condition Min Typ Max Unit
High Level Input Voltage VIH 2.1 — — V
Low Level Input Voltage VIL ——0.8V
High Level Output Voltage VOH IO=–2mA 2.4 — — V
Low Level Output Voltage VOL IO=2mA — — 0.4 V
Low Level Output Voltage, GPIO1–4 VOL IO=20mA — — 0.6 V
Input Leakage Current IL–10 — 10 µA
CTS Leakage to Ground2ICL —10—µA
Power Supply Current, Digital3IDVD pin — 28 32 mA
Power Supply Current, DSP Power Down3IDVD pin — 16 19 mA
Power Supply Current, Wake-On-Ring (ATZ) IDVD pin — 10 11 mA
Power Supply Current, Total Power Down IDVD pin — 12 15 µA
1. Measurements are taken with inputs at rails and no loads on outputs.
2. Must be met in order to avoid putting the Si2400 into factory test mode.
3. Specifications assume SE1[7:6] (MCKR) = 00b (default). Typical value is 4 mA lower when MCKR =01b and 6 mA
lower when MCKR =10b.
Table 4. DC Characteristics1
(VD=3.0 to 3.6 V, TA=0 to 70°C for K-Grade, TA=–40 to 85°C for B-Grade)
Parameter Symbol Test Condition Min Typ Max Unit
High Level Input Voltage VIH 2.1 — — V
Low Level Input Voltage VIL ——0.8V
High Level Output Voltage VOH IO = –2 mA 2.4 — — V
Low Level Output Voltage VOL IO = 2 mA — — 0.35 V
Low Level Output Voltage, GPIO1–4 VOL IO = 15 mA — — 0.6 V
Input Leakage Current IL–10 — 10 µA
CTS Leakage to Ground2ICL —3—µA
Power Supply Current, Digital3IDVD pin — 15 21 mA
Power Supply Current, DSP Power Down3IDVD pin — 9 14 mA
Power Supply Current, Wake-On-Ring IDVD pin — 5 8 mA
Power Supply Current, Total Power Down IDVD pin — 10 12 µA
1. Measurements are taken with inputs at rails and no loads on outputs.
2. Must be met in order to avoid putting the Si2400 into factory test mode.
3. Specifications assume SE1[7:6] (MCKR) =00b (default). Typical value is 4 mA lower when MCKR =01b and 6 mA
lower when MCKR =10b.
Si2400
Rev. 1.3 7
Figure 1. Test Circuit for Loop Characteristics
Table 5. AC Characteristics
(VD=3.0 to 3.6 V, or 4.75 to 5.25 V, TA=0 to 70°C for K-Grade, TA=–40 to 85°C for B-Grade)
Parameter Symbol Test Condition Min Typ Max Unit
Sample Rate Fs — 9.6 — KHz
Crystal Oscillator Frequency FXTL —4.9152—MHz
Transmit Frequency Response Low –3 dBFS Corner — 5 — Hz
Receive Frequency Response Low –3 dBFS Corner — 5 — Hz
Transmit Full Scale Level1VFS FULL = 0 (–1 dBm) — 1 — VPEAK
FULL = 1 (+3.2 dBm)2—1.58—V
PEAK
Receive Full Scale Level1VFS FULL = 0 (–1 dBm) — 1 — VPEAK
FULL = 1 (+3.2 dBm)2—1.58—V
PEAK
Dynamic Range3,4,5 DR ACT6=0
b, DCT6=10
b
(FCC) IL=100 mA —82—dB
Dynamic Range3,4,7 DR ACT = 0b, DCT = 01b
(Japan) IL=20mA —83—dB
Dynamic Range3,4,5 DR ACT = 1b, DCT = 11b
(CTR21) IL=60mA —84—dB
Transmit Total Harmonic
Distortion5,8 THD ACT = 0b, DCT = 10b (FCC)
IL=100mA —–85—dB
Transmit Total Harmonic
Distortion6,8 THD ACT = 0b, DCT = 01b
(Japan) IL=20mA —–76—dB
Receive Total Harmonic
Distortion7,8 THD ACT = 0b, DCT = 01b
(Japan) IL=20mA —–74—dB
Receive Total Harmonic
Distortion5,8 THD ACT = 1b, DCT = 11b
(CTR21) IL=60mA —–82—dB
Caller ID 60 Hz Common Mode
Tolerance9VCM > 60 dB line balance at
60 Hz 91 120 — VPEAK
Notes:
1. Measured at TIP and RING with 600 Ω termination at 1 kHz.
2. R2 should be changed to a 243 Ω resisto r when the SF5[7] (FULL) =1b.
3. DR =20 x log |Vin| + 20 x log (RMS signal/RMS noise).
4. Measurement is 300 to 3400 Hz. Applies to both transmit and receive paths.
5. Vin =1 kHz, –3 dBFS, Fs =10300 Hz.
6. ACT =SF5[4]; DCT =SF5[3:2].
7. Vin =1 kHz, –6 dBFS, Fs =10300 Hz.
8. THD =20 x log (RMS distortion/RMS signal).
9. VCM can be improved to 120 Vrms minimum by placing a 20 MΩ resistor across the C9 capacitor.
RING
Si3015 VTR IL
600 Ω
10 μF
+
–
TIP
Si2400
8 Rev. 1.3
Table 6. Voice Codec AC Characteristics
(VD=3.0 to 3.6 V or 4.75 to 5.25 V, TA=0 to 70°C for K-Grade, TA=–40 to 85°C for B-Grade)
Parameter Symbol Test Condition Min Typ Max Unit
AOUT Dynamic Range, APO = 0 VIN = 1 kHz — 40 — dB
AOUT THD, APO = 0 VIN = 1 kHz — –40 — dB
AOUT Full Scale Level, APO = 0 — 0.7 zVDD —V
PP
AOUT Mute Level, APO = 0 — 60 — dB
AOUT Dynamic Range, APO = 1,
VD= 4.75 to 5.25 V VIN = 1 kHz, –3 dB — 65 — dB
AOUT Dynamic Range, APO = 1,
VD= 3 to 3.6 V VIN = 1 kHz, –3 dB — 65 — dB
AOUT THD, APO = 1, VD= 4.75 to
5.25 V VIN = 1 kHz, –3 dB — –60 — dB
AOUT THD, APO = 1, VD= 3 to 3.6 V VIN = 1 kHz, –3 dB — –60 — dB
AOUT Full Scale Level, APO = 1 — 1.5 — VPP
AOUT Mute Level, APO = 1 — –65 — dB
AOUT Resistive Load ing, APO = 1 10 — — kΩ
AOUT Capacitive Loading, APO = 1 — — 20 pF
AIN Dynamic Range, VD= 4.75 to
5.25 V VIN = 1 kHz, –3 dB — 65 — dB
AIN Dynamic Range, VD= 3 to 3.6 V VIN = 1 kHz, –3 dB — 65 — dB
AIN THD, VD= 4.75 to 5.25 V VIN = 1 kHz, –3 dB — –60 — dB
AIN THD, VD= 3 to 3.6 V VIN = 1 kHz, –3 dB — –60 — dB
AIN Full Scale Level*—2.8—V
PP
*Note: Receive full scale level will produce –0.9 dBFS at RXD.
Table 7. Absolute Maximum Ratings
Parameter Symbol Value Unit
DC Supply Voltage VD–0.5 to 6.0 V
Input Current, Si2400 Digital Input Pins IIN ±10 μA
Digital Input Voltage VIND –0.3 to (VD + 0.3) V
Operating Temperature Range—B-Grade TA–50 to 95 °C
Operating Temperature Range—K-Grade TA–10 to 80 °C
Storage Temperature Range TSTG –40 to 150 °C
Note: Permanent device damage ma y occur if the above Absolute Maximum Ratings are exceeded. Functional operation
should be restricted to the conditions as specified in the operational sections of this data sheet. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Si2400
Rev. 1.3 9
Figure 2. Asynchronous UART Serial Interface Timing Diagram
Table 8. Switching Characteristics
(VD= 3.0 to 3.6 V or 4.75 to 5.25 V, TA= 0 to 70°C for K-Grade, TA= –40 to 85°C for B-Grade)
Parameter Symbol Min Typ Max Unit
CLKOUT Output Clock Frequency 2.4576 — 39.3216 MHz
Baud Rate Accuracy tbd –1 — 1 %
Start Bit ↓ to CTS ↑tsbc —1/(2
zBaud Rate) — ns
CTS ↓ Active to Start Bit↓tcsb 10 — — ns
RESET ↓ to RESET ↑ trs 5.0 — — ms
RESET ↑ Rise Time trs2 — — 100 ns
RESET ↑ to TXD ↓ trs3 3——ms
Note: All timing is referenced to the 50% level of the waveform. Input test levels are VIH =V
D – 0.4 V, VIL =0.4V
Receive Tim ing
Start
RXD
RXD
8-Bit Data
Mode (Default)
9-Bit Data
Mode
StopD0 D1 D2 D3 D4 D5 D6 D7
Start StopD0 D1 D2 D3 D4 D5 D6 D7 D8
tcsb tsbc
CTS
Transmit Tim ing
Start
Start
TXD
TXD
8-Bit Data
Mode (Default)
9-Bit Data
Mode Stop
StopD0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7 D8
Note: Baud rates (program m ed through register SE0) are as follows: 300,1200, 2400, 9600, 19200,
230400, 245760, and 307200 Hz.
Si2400
10 Rev. 1.3
2. Typical Application Schematic
Z1
R1 5
Refer to AN48 for Layout Guidelines
Please submit layout to Silicon Labs
for review prior to PCB fabrication.
+
C5
D4
Note 5 : R27, R28, D3, D4, Z4, Z5, RV 2 may be populated for enhanced lightning option.
C8
C13
C4
R7
R31
RV 1
FB1
GPIO3/ESC
AOUT
TI P
C22
C19
RXD
RESET_
R8
R9
R13
C9
C26
C3
Note 6: L1,L2, C38, C39, R31, R32 are for EN55022/CISPR-22 Conducted Disturbance compliance.
D3
L1
R26
R12
U1
Si2400
1
2
3
4
5
6
7
89
10
11
12
13
14
15
16
XT ALI
XT ALO
CLKOUT
VD
RXD
TXD
CTS
RESET AOUT
GPIO4
C1A
GND
ISOB
GPIO3
GPIO2
GPIO1
Q2
C16
R18
R25
R2
+
C12
Z5
D1
R1 1
C20
C39
R1 9
Q1
C18
C10
RING
R5
+
C14
Decoupling cap for U1 VD
Note 3: See "Billing Tone Immunity" sectio n for optional billing tone filter (Germany , Switzerland, South Africa) .
FB2L2
R32
Q3
U2
Si3015
1
2
3
4
5
6
7
89
10
11
12
13
14
15
16
TST A/QE2
TSTB/DCT
IGND
C1B
RNG1
RNG2
QB
QE VREG
NC/VREG2
NC/REF
DCT/REXT2
REXT
RX
NC/FI LT
TX/FI LT 2
C30
R6
C7
RV 2
C1
GPIO2/CD_
Note 1: R12, R13 and C14 are only required if complex AC termination is used (ACT bit = 1).
GPIO4/ALER T
Note 2: See "Ringer Impedance" sectio n for optional Czech Republic support.
R1 7
C24
R28
Q4
VCC
Y1
12
R24
TXD
C38
C27
Note 4: See Appendix for applications requiring UL 1950 3rd edition compliance.
CLKOUT
R10
R1 6
D2
R27
Z4
C6
CTS_
C25
GPIO1/EOFR
Figure 3. Typical Application Circuit Schematic
Si2400
Rev. 1.3 11
3. Bill of Materials
Component Value Suppliers
C1,C41150 pF, 3 kV, X7R,±20% Novacap, Venkel, Johanson, Murata, Panasonic
C3,C13 0.22 µF, 16 V, X7R, ±20% Novacap, Venkel, Johanson, Murata, Panasonic
C520.1 µF, 50 V, Elec/Tant, ±20% Venkel, Johanson, Murata, Panasonic
C6,C10,C16 0.1 µF, 16 V, X7R, ±20% Novacap, Venkel, Johanson, Murata
C7,C83560 pF, 250 V, X7R, ±20% Novacap, Venkel, Johanson, Murata, Panasonic
C9 22 nF, 250 V, X7R, ±20% Novacap, Venkel, Johanson, Murata, Panasonic
C12 1.0 µF, 16 V, Elec/Tant, ±20% Venkel, Panas onic
C1420.68 µF, 16 V, X7R/Elec/Tant,
±20% Novacap, Venkel, AUX, Murata, Panasonic
C18,C1933.9 nF, 16 V, X7R, ±20% Novacap, Venkel, Johanson , Mur ata
C20 0.01 µF, 16 V, X7R, ±20% Novacap, Venkel, Johanson, Mu r ata
C2241800 pF, 50 V, X7R, ±20% Not installed
C24,C2511000 pF, 3 kV, X7R, ±10% Novacap , Venkel, Johanson, Murata, Panasonic
C26,C27 33 pF, 16 V, NPO, ±5% Novacap, Venkel, Johanson, Murata
C30410 pF, 16 V, NPO, ±10% Not Installed
C38,C392,5 47 pF, 16 V, X7R, ±10% Venkel
D1,D26Dual Diode, 300 V, 225 mA Central Semico nductor
D3,D41BAV99 Dual Diode, 70 V Diodes Inc., OnSemiconductor, Fairchild
FB1,FB2 Ferrite Bead, 600 Ω, ±25%,
200 mA Murata
L1,L22,5 68 µH, 120 mA, 4 Ω max, ±10% TDK, Murata, Panasonic
Q1,Q3 A42, NPN, 300 V OnSemiconductor, Fairchild, Zetex
Q2 A92, PNP, 300 V OnSemiconductor, Fairchild, Zetex
Q47BCP56, NPN, 60 V, 1/2 W OnSemiconductor, Fairchild
Notes:
1. The Si2400 design survives up to 3500 V longitudinal surges without R27, R28, D3, D4, Z4, and Z5. Adding the R27, R28, D3, D4, Z4,
Z5 enhanced lightning option increases longitudinal surge survival to greater than 6600 V. The isolation capacitors C1, C4, C24, and
C25 must also be rated to greater than the surge voltage. Y-class capacitors are recommended for highest surge survival and are
required for Norway, Sweden, Denmark, and Finland.
2. For FCC-only designs: C14, C38, C39, R12, R13, R31, and R32 are not required; L1 and L2 may be replaced with a short; R2 may be
±5%; with Z1 rated at 18 V, C5 may be rated at 16 V; also see note 9.
3. If the auto answer, ring detect, and caller ID features are not used, R9, R10, C7, C8, C18, and C19 may be removed. In this case, the
RNG1 and RNG2 pins of the Si3015 should be connected to the IGND pin.
4. C22 and C30 may provide an additional improvement in emissions/immunity and/or voice performance, depending on design and
layout. Population option recommended. See "Emissions/Immunity" on page 78.
5. Compliance with EN55022 and/or CISPR-22 conducted disturbance tests requires L1, L2, C38, C39, R31, R32, and RV2. See also
“EN55022 and CISPR-22 Compliance” in Appendix A.
6. Several diode bridge configurations are acceptable (suppliers include Gener al Semi., Diodes Inc.).
7. Q4 may require copper on board to meet 1/2 W power requirement. (Contact manufacturer for details.)
8. When L1 and L2 are used, RV2 must be installed, and D1 and D2 must be 400 V.
9. The R7, R8, R15, and R16, R17, R19 resistors may each be replaced with a single resistor of 1.78 kΩ, 3/4 W, ±1%. For FCC-only
designs, 1.78 kΩ, 1/16 W, ±5% resistors may be used.
10. If the parallel phone detection feature is not used, R25 and R26 may be removed.
11. To ensure compliance with ITU specifications, frequency tolerance must be less than 100 ppm including initial accuracy, 5-year aging,
0 to 70°C, and capacitive loading.
Si2400
12 Rev. 1.3
RV1 Sidactor, 275 V, 100 A Teccor, ST Microelectronics, Microsemi, TI
RV28270 V, MOV Not Installed
R22402 Ω, 1/16 W, ±1% Venkel, Panasonic
R5 100 kΩ, 1/16 W, ±1% Venkel, Panasonic
R6 120 kΩ, 1/16 W, ±5% Venkel, Panasonic
R7,R8,R15,R16,R17,R1995.36 kΩ, 1/4 W, ±1% Venkel, Panasonic
R9,R10356 kΩ, 1/10 W, ±5% Venkel, Panasonic
R11 9.31 kΩ, 1/16 W, ±1% Venkel, Panasonic
R12278.7 Ω, 1/16 W, ±1% Venkel, Panasonic
R132215 Ω, 1/16 W, ±1% Venkel, Panasonic
R18 2.2 kΩ, 1/10 W, ±5% Venkel, Panasonic
R24 150 Ω, 1/16 W, ±5% Venkel, Panasonic
R25,R2610 10 MΩ, 1/16 W, ±5% Venkel, Panasonic
R27,R28110 Ω, 1/10 W, ±5% Venkel, Panasonic
R31,R322,5 470 Ω, 1/16 W, ±5% Venkel, Panasonic
U1 Si2400 Silicon Labs
U2 Si3015 Silicon Labs
Y111 4.9152 MHz, 20 pF, 50 ppm, 150
ESR Not Installed
Z12Zener Diode, 43 V, 1/2 W Vishay, Motorola, Rohm
Z4,Z51Zener Diode, 5.6 V, 1/2 W Vishay, Motorola, Rohm
Component Value Suppliers
Notes:
1. The Si2400 design survives up to 3500 V longitudinal surges without R27, R28, D3, D4, Z4, and Z5. Adding the R27, R28, D3, D4, Z4,
Z5 enhanced lightning option increases longitudinal surge survival to greater than 6600 V. The isolation capacitors C1, C4, C24, and
C25 must also be rated to greater than the surge voltage. Y-class capacitors are recommended for highest surge survival and are
required for Norway, Sweden, Denmark, and Finland.
2. For FCC-only designs: C14, C38, C39, R12, R13, R31, and R32 are not required; L1 and L2 may be replaced with a short; R2 may be
±5%; with Z1 rated at 18 V, C5 may be rated at 16 V; also see note 9.
3. If the auto answer, ring detect, and caller ID features are not used, R9, R10, C7, C8, C18, and C19 may be removed. In this case, the
RNG1 and RNG2 pins of the Si3015 should be connected to the IGND pin.
4. C22 and C30 may provide an additional improvement in emissions/immunity and/or voice performance, depending on design and
layout. Population option recommended. See "Emissions/Immunity" on page 78.
5. Compliance with EN55022 and/or CISPR-22 conducted disturbance tests requires L1, L2, C38, C39, R31, R32, and RV2. See also
“EN55022 and CISPR-22 Compliance” in Appendix A.
6. Several diode bridge configurations are acceptable (suppliers include Gener al Semi., Diodes Inc.).
7. Q4 may require copper on board to meet 1/2 W power requirement. (Contact manufacturer for details.)
8. When L1 and L2 are used, RV2 must be installed, and D1 and D2 must be 400 V.
9. The R7, R8, R15, and R16, R17, R19 resistors may each be replaced with a single resistor of 1.78 kΩ, 3/4 W, ±1%. For FCC-only
designs, 1.78 kΩ, 1/16 W, ±5% resistors may be used.
10. If the parallel phone detection feature is not used, R25 and R26 may be removed.
11. To ensure compliance with ITU specifications, frequency tolerance must be less than 100 ppm including initial accuracy, 5-year aging,
0 to 70°C, and capacitive loading.
Si2400
Rev. 1.3 13
4. Analog Input/Output
Figure 4 illustrates an optional application circuit to support the analog output capability of the Si2400 for voice
monitoring purposes.
Figure 4. Optional Connection to AOUT for a Monitoring Speaker
‘
Figure 5. Analog Input Circuit
Table 9. Component Values—Optional Connection to AOUT
Symbol Value
C2, C3, C5 0.1 µF, 16 V, ±20%
C4 100 µF, 16 V, Elec. ±20%
C6 820 p F, 16 V, ±20%
R1 10 kΩ, 1/10 W, ±5%
R2 10 Ω, 1/10 W, ±5%
R3 47 kΩ, 1/10 W, ±5%
U1 LM386
AOUT +
–
+ 5 V
3
2
6
5
4U1
C3 C5
C4
C6 R1
C2 R3
AIN/GPIO
Analog Input
Si2400
1 VRMS
0.1 μF
Si2400
14 Rev. 1.3
5. Functional Description
The Si2400 ISOmodem is a complete modem chipset
with integrated direct access arrangement (DAA) that
provides a programmable line interface to meet global
telephone line requirements. Available in two 16-pin
small outline packages, this solution includes a DSP data
pump, a modem controller, an analog front end (AFE), a
DAA, and an audio codec.
The modem, which accepts simple modem AT
commands, provides connect rates of up to 2400 bps,
full-duplex over the Public Switched Telephone Network
(PSTN) with V.42 hardware support through HDLC
framing. To minimize handshake times, the Si2400 can
implement a V.25-based fast connect. The modem also
supports the V.23 reversing protocol and standard alarm
formats including SIA.
The Si2400 ISOmodem provides numerous features for
embedded modem applications including caller ID
detection and decoding for the US, UK, and Japanese
caller ID formats. Both DTMF decoding and generation
are provided on chip as well. Call progress is supported
both at a high level through echoing result codes and at a
low level through user-programmable biquad filters and
parameters such as ring period, ring on/off time, and
dialing interdigit time.
This device is ideal for embedded modem applications
due to its small board space, low power consumption,
and global compliance. The Si2400 solution integrates a
silicon DAA using Silicon Laboratories’ proprietary
capacitive isolation technology. This highly integrated
DAA can be programmed to meet worldwide PTT
specifications for ac termination, dc termination, ringer
impedance, and ringer threshold. The DAA also can
monitor line status for parallel handset detection and for
overcurrent conditions.
The Si2400 is designed for rapid assimilation into existing
modem applications. The device interfaces directly
through a UART to a microcontroller. The Si2400URT-
EVB connects directly to a standard RS-232 interface.
This allows for PC evaluation of the modem immediately
upon powerup via HyperTerminal or any standard
terminal software .
The chipset can be fully programmed to meet
international telephone line interface requirements with
full compliance to FCC, CTR21, JATE, and other country-
specific PTT specifications. In addition, the Si2400 has
been designed to meet the most stringent worldwide
requirements for out-of-band energy, billing-tone
immunity, lightning surges, and safety requirements.
The Si2400 solution needs only a few low-cost discrete
components to achieve global compliance. See Figure 3
on page 10 for a typical application circuit.
Table 10. Selectable Configurations
Configuration Modulation Carrier
Frequency (Hz) Data Rate
(bps) Standard
Compliance
V.21 FSK 1080/1750 300 Full
V.221DPSK 1200/2400 1200 Full
V.22bis1,2 QAM 1200/2400 2400 No retrain
V.23 FSK 1300/2100 1200/75 Full; plus reversing
(Europe)
V.23 1300/1700 600/75
Bell 103 FSK 1170/2125 300 Full
Bell 212A DPSK 1200/2400 1200 Full
Security DTMF — 40 Full
SIA—Pulse Pulse — Low Full
SIA Format FSK 1170/2125 300 half-duplex 300 bps only
Notes:
1. The V.22 and V.22bis standards refer to V.14 DTE (UART) configurations. The Si2400 does not support V.14 breaks.
In order to support overspeeding by the remote modem, the Si2400 DTE speed must be greater than the modem
(line) data rate.
2. The Si2400 only adjusts its DCE rate from 2400 bps to 1200 bps if it is connecting to a V.22-only (1200 bps only)
modem. Because the V.22bis specification does not outline a fallback procedure, the host should implement a
fallback mechanism consisting of hanging up and connecting at a lower baud rate. Retraining to accommodate
changes in line conditions which occur during a call must b e implemented by terminating the call and redialing.
Si2400
Rev. 1.3 15
5.1. Digital Interface
The Si2400 has a universal asynchronous serial
interface (UART) compatible with standard
microcontroller serial interfaces. After power-up or
reset, the speed of the serial (Data Terminal
Equipment—DTE) interface is set by default to
2400 bps with the 8- bit, no p arity, and one stop bit (8N1)
format described below. The PCM codec se rial inter face
is disabled by default and CLKOUT is set to
9.8304 MHz after power-up or reset.
The serial interface DTE rate can be modified by writing
SE0[2:0] (SD) with the value corresponding to the
desired DTE rate. (See Table 11.) This is accomplished
with the command ATSE0=xx where xx is the
hexadecimal valu e of th e SE0 re g iste r.
Immediately after the ATSE0=xx string is sent, the host
UART must be reprogrammed to the new DTE rate in
order to communicate with the Si2400.
The three highest DTE rates (228613, 245760, 307200)
are required for transferring PCM data from the host to
the Si2400 PCM interface for the transmission of voice
over the phone line or through the voice codec.
5.2. Configurations and Data Rates
The Si2400 can be configured to any of the Bell and
CCITT operation modes in Table 12. The modem, when
configured for V.22bis, will connect at 1200 bps if the far
end modem is configured for V.22. This device also
supports SIA and other protocols for the security
industry. Table 10 provides the modulation method,
carrier frequencies, data rate, baud rate and notes on
standard compliance for each modem configuration of
the Si2400. Table 12 shows example register settings
(S07) for some of the modem configurations.
As shown in Figure 6, 8-bit and 9 -bit dat a modes refer to
the DTE format over the UART. Line data formats are
configured thro ugh registers S07 (MF1) and S15 (MLC).
If the number of bits specified by the DTE format differs
from the number of bits specified by the DCE (Data
Communications Equipment or Line) format, the MSBs
will either be dropped or bit-stuffed, as appropriate. For
example, if the DTE format is 9 data bits (9N1), and the
line data format is 8 data bits (8N1), then the MSB from
the DTE will be dropped as the 9-bit word is passed
from the DTE side to the DCE (line) side. In this case,
the dropped ninth bit can then be used as an escape
mechanism. However, if the DTE format is 8N1and the
line data format is 9N1, an MSB equal to 0 will be added
to the 8-bit word a s it is passed from the DTE side to the
DCE side.
The Si2400 UART does not continuously check for stop
bits on the incoming digital data. Therefore, if the TXD
pin is not high, the RXD pin may echo meaningless
characters to the host UART. This requires the host
UART to flush its receiver FIFO upon initialization.
Figure 6. Link and Line Data Formats
5.2.1. Command/Data Mode
Upon reset, the modem will be in command mode and
will accept AT-style commands. An outgoing modem
call can be made using the “ATDT#” (tone dial) or
“ATDP#” (pulse dial) command after the device is
configured. If the handshake is successful, the modem
will respond with the “c”, “d”, or “v” string and enter data
mode. (The byte following the “c”, “d”, or “v” will be the
first data byte.) At th is poin t, AT-style commands are not
accepted. There are three methods which may be used
to return the Si2400 to command mode:
Table 11. DTE Rates
DTE Rate (bps) SE0[2:0] (SD)
300 000
1200 001
2400 010
9600 011
19200 100
228613 101
245760 110
307200 111
Table 12. Modem Configuration Examples
(S07[7] (HDEN) = 0, S07[6] (BD) = 0)
Modem Protocol Register S07 Values
V.22bis 0x06
V.22 0x02
V.21 0x03
Bell 212A 0x00
Bell 103 0x01
V.23 (1200 tx, 75 rx) 0x16
V.23 (75 tx, 1200 rx) 0x24
V.23 (600 tx, 75 rx) 0x12
V.23 (75 tx, 600 rx) 0x20
DTE Interface
D ata R a te: S E0[2 :0] (S D )
D ata F orma t: S E 0 [3] (N D )
D C E (L ine ) Interfa ce
D ata R ate : S 0 7 (M F 1 )
Data Form at: S15 (MLC)
Si3015Si2400
RJ11
TXD
RXD
Si2400
16 Rev. 1.3
Use the ESC pin—To program the GPIO3 pin to
function as an ESCAPE input, set GPIO3
SE2[5:4] = 11b. In this setting, a positive edge
detected on this pin will return the modem to
command mode. The “ATO” string can be used to re -
enter data mode.
Use 9-bit data mode—If 9-bit data format with
escape is programmed, a 1 detected on bit 9 will
return the modem to command mode. (See Figure 2
on page 9.) This is enabled by setting
SE0[3] (ND) = 1b and S15[0 ] (NBE) = 1b. The ATO
string can be used to reenter data mode. Ninth bit
escape does not work in the security modes.
Use TIES—The time independent escape sequence
is a sequence of three escape characters (“+”
characters by default). Once these characters have
been recognized, the modem enters the Command
state without se nding a confirm ing result code to the
terminal. The modem then starts an internal prompt
delay timer. From that point on if an AT<CR>
(attention) command is received before the timer
expires, the timer is stopped and the “O” response
code is sent to the terminal. This indicates that the
Si2400 is in command mode.
If any other data is received while the timer is
running, the timer is stopped, the device returns to
the online state, and the data appearing on TXD is
sent to the remote modem.
If the timer expires, a confirming “O” response code
is sent to the terminal indicating that the modem is in
command mode.
TIES is enabled by writing register
S14[5] (TEO) = 1b. Both the escape character “+”
and the escape time-out period are programmable
via registers S0F (TEC) and S10 (TDT), respectively .
Note: TIES is not the recommended escape solution for the
most robust designs. Any data string containing the
sequence “+++AT<CR> ” will interrupt a data sequence
erroneously.
Whether using an escape method or not, when the
carrier is lost, the modem will automatically return to
command mode and report “N”.
5.2.2. 8-Bit Data Mode (8N1)
The 8-bit da ta mode is the default mo de after power-up
or a reset and is set by SE0[3] (ND) = 0b. It is
asynchronous, full duplex, and uses a total of 10 bits
including a start bit (logic 0), 8 data bits, and a stop bit
(logic 1). Data received from the remote modem is
transferred from the Si2400 to the host on the RXD pin.
Data transfer to the host begins when the Si2400
asserts a logic 0 start bit on RXD. Data is shifted out of
the Si2400 LSB first at the DTE rate determined by the
SE0[2:0] (SD) setting and terminates with a stop bit.
Data from the host for transmission to the remote
modem is shifted to the Si2400 on TXD, beginning with
a start bit, LSB first at the DTE rate determined by the
SE0[2:0] setting and terminat es with a stop bit. After the
middle of the stop bit time the Si2400 will begin looking
for a logic 1 to logic 0 transition signaling the start of the
next character on TXD to be sent to the line (remote
modem).
5.2.3. 9-Bit Data Mode (9N1)
The 9-bit data mode is set by SE0[3] (ND) = 1b. It is
asynchronous, full duplex, and uses a total of 11 bits
including a start bit (logic 0), 9 data bits, and a stop bit
(logic 1). Data received fro m the line (remo te mode m) is
transferred from the Si2400 to the host on the RXD pin.
Data transfer to the host begins when the Si2400
asserts a logic 0 start bit on RXD. Data is shifted out of
the Si2400 LSB first at the DTE rate determined by the
SE0[2:0] (SD) setting and terminates with a stop bit.
Data from the host for transmission to the line (remote
modem) is shifted to the Si2400 on TXD, beginning with
a start bit, LSB first at the DTE rate determined by the
S-Register SE0[2:0] (SD) setting and terminates with a
stop bit. After the middle of the stop bit time the Si2400
will begin looking for a logic 1 to logic 0 transition
signaling the start of the next character on TXD to be
sent to the line (remote modem).
The ninth data bit may be used to in dicate an escape by
setting S15[0] (NBE) = 1b. In this mode, the ninth data
bit will normally be set to 0 when the modem is online.
When the ninth data bit is set to 1, the modem will go
offline into Command mode and the next frame will be
interpreted as an AT command. Data mode can be
reentered using the ATO command.
5.2.4. Flow Control
No flow control is needed if the DTE rate and DCE rate
are the same. If the serial link (DTE) data rate is set
higher than the line (DCE) rate of the modem, flow
control is required to prevent loss of data to the
transmitter.
To control data flow, the clear-to-send (CTS) pin is used.
As shown in Figure 2 on page 9, the CTS pin will
normally be high, and will be low whenever the modem
is able to accept new data. The CTS pin will go high
again as soon as a start bit is detected on the TXD pin
and will remain high until the modem is ready to accept
another character.
Si2400
Rev. 1.3 17
5.3. Low Power Modes
The Si2400 has three low power modes. These are
described below:
DSP Powerdown. The DSP processor can be
powered down by setting register
SEB[3] (PDDE) = 1b.
In this mode, the serial interface still functions and
the modem will detect ringing and intrusion.
However, no modem modes or tone detection
features will function.
Wake-Up-On-Ring. By issuing the ATz command,
the Si2400 goes into a low power mod e wh er e bo th
the microcontroller and DSP are powered down.
Only an incoming ring or a total reset will power up
the chip again. Return from wake-on-ring will trigger
the ALERT pin if S62[4] (WOR) = 1b (WOR = 0b by
default).
Total Powerdown. Setting SF1[5] = 1b and
SF1[6] = 1b will place the Si2400 into a total
powerdown mode. All logic is powered down,
including the crystal oscillator and clock-out pin.
Only a hardware res et can re start the Si240 0.
5.4. Global DAA Operation
The Si2400 chipset contains an integrated silicon direct
access arrangement (silicon DAA) that provides a
programmable line interface to meet international
telephone line requirements. Table 13 gives the DAA
register settings required to meet various country PTT
standards. A detailed description of the registers in
Table 13 can be found in "Appendix A—DAA Operatio n"
on page 78.
Table 13. Country-Specific Register Settings
Register SF5 SF7 SF6 S62
Country OHS ACT DCT RZ RT LIM VOL FLVM LLC
Australia111010000 00
Brazil20001000000
CTR211, 3, 4 01100010 01
Czech Republic 0 1 10 0 0 0 0 0 0
FCC1, 5 00100000 00
Latvia 01110010 00
Malaysia1,6 00010000 00
New Zealand 0 1 10 0 0 0 0 0 0
Nigeria 0 1 11 0 0 1 0 0 0
Philippines10001000010
Poland7, Slovenia 0 0 10 1 1 0 0 0 0
South Africa710101000 00
South Korea700011000 00
Note:
1. See "DC Termination" on page 79 for more information.
2. The following countries require the same settings as Brazil: Armenia, China, Egypt, Georgia, Japan, Jordan,
Kazakhstan, Kyrgyzstan, Malaysia, Muldova, Oman, Pakistan, Qatar, Russia, Syria, Taiwan, Thailand, Ukraine.
3. The following countries require the same settings as CTR21: Austria, Bahrain, Belgium, Bulgaria, Croa ti a , Cyprus,
Denmark, Estonia, European Union, Finland , France, Germany, Greece, Guadeloupe, Iceland, Ireland, Israel, Italy,
Lebanon, Liechtenstein, Luxembourg, Malta, Martinique, Morocco, Netherlands, Norway, Polynesia (French),
Portugal, Reunion, Spain, Sweden, Switzerland, Turkey, and the United Kingdom.
4. When changing into or out of CTR21 Mode, LLC should be written first. SDF must be enabled (i.e., DGSR ≠ 0) and
SFS should be reprogrammed before each call.
5. The following countries require the same settings as FCC: Argentin a, Brunei, Canada, Chile, Columbia, Duba i,
Equador, El Salvador, Guam, Hong Kong, Hungary, India, Indonesia, Kuwait, Macao, Mexico, Peru, Puerto Rico,
Romania, Saudi Arabia, Singapore, Slovakia, Tunisia, UAE, USA, Venezu ela, Yemen.
6. Supported for loop current ≥ 20 mA.
7. SF5[1] (RZ) shou ld only be set for Poland, South Africa and South Korea if the ringer impedance network (C15, R14,
Z2, Z3) is not populate d.
Si2400
18 Rev. 1.3
5.5. Parallel Phone Detection
The Si2400 has the ability to detect a phone or other
device that is of f hook on a shared line. This enables th e
ISOmodem to avoid interrupting a call in progress on a
shared line and to intelligently handle an interruption by
another device when the Si2400 is using the line. An
automatic algorithm to detect parallel phone intrusion
(defined as an off-hook parallel handset) is provided by
default.
5.5.1. On-Hook Intrusion Detection
To implement intrusion detection, the Si2400 uses loop
voltage sense register SDB (LVCS). When on hook,
LVCS monitors the line voltage. (When off-hook, it
measures line current.) LVCS has a full scale of 87 V
with an LSB of 2.75 V. The first code (0 →1) is skewed
such that a 0 indicates that the line voltage is < 3.0 V.
The voltage accuracy of LVCS is ±20%. The user can
read these bits directly when on hook through register
SDB (LVCS).
The automatic on-hook detector algorithm can be
tripped by either an absolute level or by a voltage
differential by selecting S13[3] (ONHD) = 0b for
absolute or S13[3] (ONHD) = 1b for differential. If the
absolute detector is chosen, the Si2400 algorithm will
detect an intrusion if LVCS is less than the value st ored
in on-hook intrusion threshold, S11[4:0] (AVL). In other
words, an intrusion has occurred if LVCS < AVL.
AVL defaults to 1000b, or 25 V on powerup. The
absolute detector is the correct method to use for most
countries and should also be used to detect the
presence (or absence) of a line connection.
Under the condition of a very short line and a current-
limiting telephone off hook, the off-hook line voltage can
be as high as 40 V. The minimum on-hook voltage may
not be much greater. This condition can occur on phone
lines with current-limiting specifications such as France.
For these lines, a differential detector is more
appropriate.
The differential detector method checks line status
every 26.66 ms. The detector compares (LVCS (t –
0.02666) – LVCS (t)) to the differential threshold level
set in register S11[7:5] (DVL). The default for DVL is
0x02 (5.5 V). If the threshold is exceeded (LVCS (t –
0.02666) – LVCS (t) > DVL), an intrusion is detected. If
(LVCS (t) – LVCS (t – 0.02666) > DVL), then the
intrusion is said to have terminated.
Figure 7. Loop Voltage—LVCS Transfer Function
0 3 6 9 121518212428303336394245475154576063666972 100
0
5
75 78 81 84 87
LVCS
BITS
Loop Voltage ( V)
10
15
20
25
30
Si2400
Rev. 1.3 19
5.5.2. Reporting of an On-Hook Intrusion
The reporting of an on-hook intrusion is the same
whether or not the differential or absolute algorithm is
chosen.
An “i” result code is sent when an intrusion is detected.
Conversely a n “I” result code is sent when an intrus ion
has terminated. S14[1] (IND) indicates the current
intrusion status and is set for as long as an intrusion is
detected.
In addition, if the LVCS returns a value of zero, an “l”
result code is sent to the host. If the LVCS becomes
non-zero after having gone to zero, an “L” result code is
sent to the host. S14[2] (NLD) indicates the curre nt line
voltage st atus and is set for a s long as the LVCS is zero.
It is possible to suppress the result codes by setting
S14[7] MRCD = 1b and selectively re-enabling desired
result codes using the S62 register. Suppressing result
codes in this fashion does not affect the setting of the
NLD and IND bits of the S14 register. Suppressing the
result codes is the best approach if polling the S14
register to monitor the intrusion status is preferred.
It is also possible to suppress the result codes by
setting S33[6] (DON). However, this approach will stop
the updating of the S14 register, rendering the on-hook
intrusion algorithm completely disabled. This approach
may be used if the host checks LVCS directly prior to
going off-hook.
5.5.3. Off-Ho o k In trusi o n De te ct io n
When the Si2400 is off-hook, it can detect another
phone going off-hook by monitoring the dc loop current.
The loop current sense transfer function is shown in
Figure 8 with the upper curve representing CTR21
(current limiting) operation and the lower curve
representing all other modes. The overload points
indicate excessive current draw. The user can read
these bits directly through SDB (LVCS). Note that as in
the line voltage sense, there is hysteresis between
codes (0.375 mA for CTR21 mode and 0.75 mA for the
alternate mode).
The off-hook intrusion algorithm does not begin to
operate immediately after going off-hook. This is to
avoid triggeri ng an off- hook intrusion interrup t due to of f-
hook transients. The time between going off-hook and
enabling the intrusion algorithm defaults to 1 second
and may be set via S82[7:4] (IST).
Once the intrusion settling time (IST) has elapsed, the
Si2400 executes one of the three off-hook intrusion
algorithms, depending on the settings of
SDF[6:0] (DSGR) and S13[4] (OFHD). See Table 14.
5.5.4. Differential Algorithm #1 (default)
If (LVCS (t – 800 ms) – LVCS (t)) > S12[7:5] (DCL), then
an intrusion is deem ed to have taken place. If (LVCS (t)
– LVCS (t – 800 ms)) > DCL, then the intrusion is
deemed to have completed. Default DCL is 2. This
comparison occurs every 200 ms.
Figure 8. Loop Current—LVCS Transfer Function
Table 14. Off-Hook Intrusion Algorithms
Algorithm OFHD SDF
Differential #1 1 0
Differential #2 1 ≠0
Absolute 0 x
0 3 6 9 1215182124 30333639 424548515457 6063666972 140
75 78 81 84 87 9093
Loop Current
(mA)
LVCS
BITS
27
Overload
0
5
10
15
20
25
30
CTR21
Si2400
20 Rev. 1.3
5.5.5. Differential Algorithm #2
This differential algorithm has features added to
Differential Algorithm #1. The additional features are as
follows:
Programmable deglitch filter to minimize false
intrusions
Ability to preset initial LVCS refe rence prior to going
off-hook
Optional time window where intrusions are blocked
and ignored
5.5.6. Deglitch Filter
To avoid triggering an off-hook intrusion interrupt due to
a transient or glitch on the telephone line, a deglitch
filter is inserted before the off-hook intrusion algorithm.
The sample rate of the deglitcher is set by
SDF[6:0] (DGSR). (If DGSR = 0, the Differential
Algorithm #1 is implemented.) Before a sample is
passed to the off-hook intrusion algorithm, it must be
confirmed by a subsequent sample of the same value.
Otherwise, it is not submitted to the off-hook algorithm.
In order to filter out glitches of up to 1 second in
duration, for example, DGSR should be set to 1 second
(SDF[6:0] = 011001b). In this example, an intrusion
event that lasts for more than two seconds is
guaranteed to be treated as a real intrusion. Intrusion
events between one second and two seconds in
duration may or m ay no t b e tr ea te d as an in tru sio n. T he
recommended setting for DGSR is one second, which
should work for most applications.
Once a sample has been deemed valid by the deglitch
filter, the off-hook algorithm operates as follows:
If (LVCS (t – 80 ms zDGSR) – LVCS (t)) > DCL, then an
intrusion is deemed to have taken place. Default DCL
is 2. This comparison occurs every 40 ms zDGSR.
Because the comp ared va lue is continually up dated, the
off-hook intrusion algorithm automatically adjusts to
account for drift in line resistance.
5.5.7. LVCS Initialization
If an intrusion begins within the time window defined by
S82[7:4] (IST), it is possible for an intrusion to go
unreported because the initial LVCS used as the
reference is sampled after the intrusion has begun.
S12[4:0] (ACL) is used to avoid this problem. Prior to
going off-hook, the host can set the ACL register to a
known value of LVCS with the Si2400 off-hook and all
parallel phones or other devices on-hook. If this value is
not known, such as on the first off-hook event using this
specific phone line, ACL should be set to 0, indicating
no known LVCS reference.
Once the Si2400 goes back on-hook, it automatically
writes the value of the last known LVCS sample prior to
an intrusion, if any, into ACL. Therefore, ACL may be
used for the next off-hook event even if the current off-
hook sample contains an intrusion. Except for the first
initialization, no host intervention is necessary.
The Si2400 clears ACL automatically under a hardware
reset. Additionally, ACL is cleared if the modem is on-
hook, and the phone line is disconnected and then
reconnected once again.
If the host hardware reset s the Si240 0 between of f- hook
events, the host may choose to store the ACL value
prior to reset, and then restore this value to ACL prior to
the next off-hook event.
5.5.8. Intrusion Blocking
Differential Algorithm #2 ma y be disa b led for a pe rio d of
time after dialing begins. This can avoid triggering an
off-hook intrusion interrupt due to pulse dialing or line
transients from central office switching. The method to
block the intrusion algorithm is set via S82[1:0] (IB). If
IB = 10b is chosen, S29 (IS) can be used to set this
blocking to an absolute time.
In order to detect if an intrusion does occur during
blocking and is sustained until after the blocking, the
Si2400 will measure the difference in LVCS between the
sample before blocking and the sample after blocking.
5.5.9. Absolute Algorithm
If the absolute detector is chosen (S13[4] [OFHD] = 0b),
the Si2400 will detect an intrusion under the condition
that LVCS is less than the off-hook intrusion threshold,
S12[4:0] (ACL). In other words, it is determined that an
intrusion has occurred if LVCS < ACL. ACL defaults to 0
(12 mA) on powerup. Because the loo p current can vary
from 20 mA to 100 mA, depending on the line, a factory
preset threshold is not useful.
To use this absolute mode, the host must measure the
line current and set the threshold accordingly. A
measurement of the loop current is accomplished by
going off-hook (issuing the “ATDT;” command), reading
LVCS after 800 ms, and going back on hook using the
“ATH” command. This measured value of LVCS should
be used to determ ine the threshold register ACL. If this
method is used, the loop current should be measured
on a periodic basis to account for drif t in line resist ance.
5.5.10. Reporting Off-Hook Intrusions
The primary method of reporting an off-hook intrusion
event to the host is through the use of the ALERT pin.
The ALERT function is assigned to GPIO4 by setting
SE2[7:6] (GPIO4) = 11b.
In general, “i” and “I” result codes are sent when the
modem detects an intrusion. However, it is important to
note that these result codes are not always reported.
When the modem is in the data mode, the “i” and “I”
Si2400
Rev. 1.3 21
result codes are suppressed, and the ALERT pin is the
only method of reporting an intrusion to the host.
The “i” and “I” result codes may be sent to the host
under the following conditions:
1. If the modem is in the process of establishing a connection
using the “ATDT#<cr>” or “ATA<cr>” commands and prior
to the “c”, “v”, or “d” result codes.
2. If the modem is in command mode and a call is initiated
using “ATDT#;” command.
3. If the modem is used in the security modes (ATDT #!0-!7)
(except !2).
4. If the modem is used in the !2 security mode while the
modem is not actively receiving/sending FSK data.
Once the ALERT pin is asserted as a consequence of
an intrusion, it is the responsibility of the host software
to negate it by clearing SE3[3] (GPD4) directly.
S14[1] (IND) is an indication of the current intrusion
status. It is updated whenever the “i” and “I” result
codes are sent to the host or when the ALERT pin is
asserted. If set, IND indicates that an intrusion event is
in progress. In addition, the status of IND persists for
800 msec after an off hook to on-hook event. After
800 msec has elapsed, IND functions as documented
for the on-hook intrusion algorithm. This delay
preserves the S14 register contents at the time the
ALERT is asserted.
When using the modem as a standard data modem and
the ALERT pin asserts, the host software may need to
force the modem back into command mode. In the
command mode, the host can determine if the ALERT
assertion was caused by an intrusion or a carrier loss by
querying the S14 register.
If the modem is dialing (after the ATDT string but before
the “c”, “v”, or “d” result codes), sending any character
places the modem back into command mode. In the
case in which the modem has already connected (in
data mode after the “c”, “v” or “d” result code has been
sent), an escape sequence is required to place the
modem in the command mode.
The best method of regaining control, without having to
know the exact status of the modem, is by issuing an
escape sequence (asserting the ESC pin and waiting a
short period of time) and sending a carriage return
character. The escape se quence takes c are of the ca se
in which the modem is in the connected state, and the
carriage return character abo rts the d ialing if the modem
is in the process of dialing to get a connection. If the
modem is already on-hook and in command mode, the
carriage return character and escape sequence are
benign events.
5.6. Loop Current Detection
In addition to monitoring parallel phone intrusion, it is
possible to monitor the loss of loop current. This feature
can be enabled by setting SE82[3] (LCLD) = 1. This
feature is disabled by default. If the loop current is too
low for normal DAA operation, the “l” result code is sent,
and S14[2] (NLD) is set. Once the loop current returns
to a normal curr ent state, the “L ” res ult co de is s ent a nd
S14[2] (NLD) is cleared. The ALERT pin is also
asserted if enabled. The “L” and “l” result codes are not
always sent. The principles governing the reporting of
the “i” and “I” result codes apply to the “L” and “l” result
codes. The status of the S14 register is unchanged for
800 msec after an off-hook to on-hook event. This delay
preserves the S14 register contents at the time the
ALERT is asserted.
5.7. Carrier Detect/Loss
The Si2400 can provide the functionality of a loss-of-
carrier pin similar to the CD pin functionality in an RS-
232 connection. If programmed as an ALERT, GPIO4
will go high in data mode when either parallel phone
intrusion or a loss-of-carrier is detected. When used in
this manner, the host detects a low-to-high transition on
GPIO4 (ALERT), escapes into command mode, and
reads S14[1] (IND). If high, IND indicates intrusion. If
low, IND indicates loss-of-carrier.
A carrier detect function may also be implemented by
setting SE2[3:2] (GPIO2) = 01b, SE4[0] (TRSP) =0b,
and SOC[7] (CDE) = 1b.
If the Si2400 does not reliably detect loss of carrier, use
the following AT command string:
ATSE8=00SE6=00SE5=25SE8=01SE6=0ASE5=3DSE8=00
This moves the carrier-off level to within 0.5 dB of the
carrier-on level. (The default is 2.5 dB.) This reduces
the likelihood that the Si2400 will detect its own output
as a remote modem carrier.
5.8. Overcurrent Detection
The Si2400 will always go off hook with the current-
limiting mode enabled. This allows no possibility of
damage for voltages up to about 48 V. However, at
higher voltages the 43 V Zener protection device will
begin to conduct and could be damaged if the power is
applied for too long.
The Si2400 will detect the value of the loop current at a
programmable time set by S32 (OCDT) after going off-
hook (default = 20 ms). If th e loop current is too high, an
“x” will be echoed back to the host to indicate a fault
condition. The host may then check S14[3] (OD) to
confirm an overcurrent condition.
The user can optiona lly put the Si2400 into a lowe r drive
Si2400
22 Rev. 1.3
mode, which is similar to the current-limiting mode but
has reduced hookswitch drive. This feature allows the
Si2400 to remain off-hook on a digital line for a longer
period of time without damage. If the Si2400 does not
detect overcurrent after the time set by S32 (OCDT), the
correct line termination is applied. Another option is
setting S13[5] (OFHE) = 1b. When this bit is set, the
Si3015 is forced to CTR21 termination during the short
period of time from the off-hook event until the timeout
defined by OCDT. After the OCDT timeout, the desired
dc termination is restored.
If it is determined that a false overcurrent condition has
been detected, the host may choose to set
S62[6] (OCR) = 1b to disable the reporting of the “x”
result code.
5.9. Caller ID Decoding Operation
The Si2400 supports full caller ID detection and decode
for US Bellcore, UK, and Japanese standards. To use
the caller ID decoding feature, the following set-up is
necessary:
1. Set SE0[3] (ND) =0b (Set modem to 8N1 configuration)
2. Set S13[1] (CIDU) =1
b (Set modem to Bellcore type caller
ID) or S13[2] (CIDB) =1b (Set modem to UK type caller
ID) or S13[7] (JID) =1b (Set modem to Japanese type
caller ID)
5.9.1. Bellcore Caller ID Operation
The Si2400 will detect the first ring burst signal and
echo an “R” to the host. The device will then start
searching for the caller ID preamble sequence after the
appropriate time-out. When 50 continuous mark bits
have been detected, the “m” response will be echoed to
indicate that the mark has been detected and that caller
ID data will follow.
At this point the algorithm will look for the first start bit,
assemble the characters and transmit them out of the
serial port as they are de te ct ed .
Finally, the Si2400 will continue detecting ring bursts
and echoing “R” for each burst and will automatically
answer after the correct number of rings set by S00
(NR).
5.9.2. UK Caller ID Operation
When the Si2400 detects a line reversal, it will echo an
“f” to the host. It will then start searching for the Idle
State Tone Alert Signal. When this signal has been
detected, the Si2400 will transmit an “a” to the host.
After the Idle State Tone Alert Signal is completed, the
Si2400 will apply the wetting pulse for the required
15 ms by quickly going off hook and on hook. From this
point on, the algorithm is identical to that of Bellcore in
that it will search for the c hannel seizure signal and the
marks before echoing an “m” and will then report the
decoded caller ID data. The wetting pulse may cause
false intrusions to be detected. To prevent this, setting
S14[7] (MRCD) = 1b is recommended.
5.9.3. Japan Caller ID Operation
After a polarity reversal and the first ring burst are
detected, the Si2400 is taken off hook. The Si2400 then
looks for mark bits. If three seconds elapse without
detecting a mark bit, the Si2400 hangs up and echoes
an “H”. Otherwise, after 40 1s (marks) have been
detected, the Si2400 will search for a start bit, echo an
“m” for mark, and begin assembling characters and
transmitting them out through the serial port. When the
carrier is lost, the Si2400 immediately hangs up and
echoes “N”.
5.9.4. Force Caller ID Monitor
The Si2400 may be used to continuously monitor the
phone line for the caller ID mark signals. This can be
useful in systems that require detection of caller ID data
before the ring signal, voice mail indicator signals, and
Type II caller ID monitor support. To force the Si2400
into caller ID monitor mode, set SOC[6:5] (CIDM) = 11b.
In addition, the Force Caller ID Monitor feature can
require that the caller ID FSK data be preceded by
either a DTMF A or D or a channel seizure pattern by
setting CIDM appropriately.
Note: CIDM should be disabled before going off-hook.
5.9.5. DTMF Caller ID
In order for the Si2400 to detect DTMF-based caller ID,
it must be put into the data mode for DTMF detection.
This mode behaves similarly to the ATA0 and ATDT!0
modes in that once a command is sent, ATO must be
sent to return to the detection state. The following
commands place the Si2400 into an on-hook DTMF
detection mode:
ATS1D=02SF0=02SE8=02SE6=01S83=66O<CR>
The Si2400 cannot distinguish between DTMF sent
from the central office or DTMF sent from a parallel
phone. For this reason, the host processor will need to
know the proper format of the caller ID information to
interpret whether the incoming digits are caller ID
information or if they ar e the o utgo ing dig its of a parallel
phone. DTMF-based caller ID typically uses the
extended DTMF digits (A, B, C, D, *, #) to indicate the
start and end of the caller ID data.
While in this mode, the Si2400 will not report detection
of ringing and must rely on the caller ID string as an
indication that the phone is ringing. It is necessary to
end the DTMF detection mode by sending the ATH
command before originating (ATDT) or answering (ATA)
a call.
Si2400
Rev. 1.3 23
5.10. Tone Generation and Tone Detection
The Si2400 provides comprehensive and flexible tone
generation and detection. This includes all tones
needed to establish a circuit connection and to set up
and control a communication session. The tone
generation furnishes the DTMF tones for PSTN auto
dialing and the supervisory tones for call establishment.
The tone detection provides support for call progress
monitoring. The detector can also be user-programmed
to recognize up to four tones and two tone detection
bandpass filters.
DTMF tones may be detected and generated by using
the “ATA0” and “ATDT!0” commands described in the
AT command section. A description of the user-
programmable tones can be found in "7.1.DSP
Registers" on page 40.
The Si2400 DTMF decoder is designed for single loop
applications such as local detection of a parallel DTMF
device. Applications requiring DTMF detection across
two loops such as programming via a remote keypad
are not suppor te d.
5.11. PCM Data Mode
The Si2400 has the ability to bypass the modem
algorithm and send 14-bit PCM data, sampled at
9600 Hz, across the DAA. To use this mode, it is
necessary to set the serial link (DTE) rate to at least
228613 bps SE0[2:0] (SD) = 101b, set S13[0] (PCM)
=1
b, and set SE1[7:6] (MCKR) = 00b. The data format
(Figure 9) requires that the high byte be sent first
containing bits D13–D7. The LSB (B0) must equal zero.
The low byte must be sent next containing bits D6–D0;
the LSB (B0) must equal o ne. The receive da ta format is
the same.
In PCM data mode, the line can be answered or
originated using the “ATDT#;” command. (The “;” is
used to keep the modem from leaving the command
mode.) When PCM data mode is enabled (set
S13[0] (PCM) = 1b and SE4[5:4] (DRT) = 001b
(default)), data will immediately begin streaming into
and out of the serial port at a 9600 Hz z2 word rate. In
this mode, the controller will not detect dial tones or
other call progress tones. If desired, the user can
monitor these tones using manual call progress
detection prior to entering the PCM data mode.
To exit the PCM data mode, an escape must be
performed either by pulsing the ESC pin or by using 9-
bit data mode and setting the ninth bit. (TIES cannot be
used in PCM data mode.) The escape command will
disable PCM streaming, and the controller will again
accept AT style commands.
Figure 9. PCM Timing
PCM Transm it Tim ing
PC M Receive Tim ing
8 -B it Da ta H ig h -Byte L o w -Byte
8 -B it Da ta H ig h -Byte L o w -Byte
RXD
Note: Baud rates (programmed through register SEO) can be set to the following: 228613, 245760 and 307200.
D7 D8 D9 D10 D11 D12 D13 D6D5D4
D3
D2D1D0
Start B0 B1 B2 B3 B4 B5 B6 B7 Stop Start B0 B1 B2 B3 B4 B5 B6 B7 Stop
TXD D7 D8 D9 D10 D11 D12 D13 D6D5D4
D3
D2D1D0
Start B0 B1 B2 B3 B4 B5 B6 B7 Stop Start B0 B1 B2 B3 B4 B5 B6 B7 Stop
Si2400
24 Rev. 1.3
Figure 10. Signal Routing
Data Mode (DRT = 00b)
Si3015
Si2400
DSP
A. DSPOUT
DSPIN
AOUT
(Call Progress) AIN
Voice Mode (DRT = 01b)
Si3015
Si2400
DSP
B. DSPOUT
DSPIN
AOUT
(Voice Out) AIN
(Voice In)
Loopback Mode (DRT = 10b)
Si2400
DSP
C. DSPOUT
DSPIN
AOUT AIN
Codec Mode (DRT = 11b)
Si3015
Si2400
DSP
D. DSPOUT
DSPIN
AOUT
(Voice Out) AIN
(Voice In)
RJ11
RJ11
RJ11
RJ11
RJ11
TXD
RXD
TXD
RXD
TXD
RXD
TXD
RXD
Si2400
Rev. 1.3 25
5.12. Analog Codec
The Si2400 features an on-chip, voice quality codec.
The codec consists of a digital to analog converter
(DAC) and an analog to digital converter (ADC). The
sample rate for the codec is set to 9.6 kHz. When the
codec is powered on (SE4[1] [APO] = 1b), the output of
the DAC is always present on the Si2400 AOUT pin.
When the codec is powered off (APO = 0b), a PWM
output is present on the AOUT pin instead. In order to
use the ADC, one of the four GPIO pins must be
selected as an analog input (AIN) by programming SE2
(GPIO).
Figure 10 shows the various signal routing modes for
the Si2400 voice co dec, which are progr ammed thr ough
register SE4[5:4] (DRT). Figure 10A shows the data
routing for data mode. This is the default mode used for
modem data formats. In this configuration, AOUT
produces a mixed sum of the DSPOUT and DSPIN
signals and is typically used for call progress monitoring
through an external speaker. The relative levels of the
DSPOUT and DSPIN signals that are output on the
AOUT pin can be set through SF4[1:0] (ATL) and
SF4[3:2] (ARL).
Figure 10B shows the format for sending analog voice
across the DAA to the PSTN. AIN is routed directly
across the DAA to the telephone line. In this
configuration, AOUT produces a mixed sum of the
DSPOUT and DSPIN signals. The relative levels of the
DSPOUT and DSPIN signals that are output on the
AOUT pin can be set through registers ATL and ARL.
The DSP may process these signals if it is not in PCM
data mode. Thus, the DSP may be used in this
configuration, for example, to decode DTMF tones. This
is the mode used with the “!0” and “A0” co mmands.
Figure 10C shows the loopback format, which can be
used for in-circuit testing.
Figure 10D shows the codec mode. This format is
useful, for example, in voice prompting, speaker
phones, or any systems involving digital signal
processing. In this mode, DSPOUT is routed to both the
AOUT pin and to the telephone line, and AIN is routed
directly to DSPIN.
In all the DRT formats, the DSP must be in PCM mode
in order to pass DSPIN and DSPOUT directly to and
from TXD and RXD.
5.13. V.23 Operation/V.23 Reversing
The Si2400 supports full V.23 operation including the
V.23 reversing procedure. V.23 operation is enabled by
setting S07 (MF1) = xx10xx00b or xx01xx10b. If
S07[5] (V23R) = 1b, then the Si2400 will transmit data at
75 bps and receive data at either 600 or 1200 bps. If
S07[4] (V23T) = 1b, then the Si2400 will receive data at
75 bps and transmit data at either 600 or 1200 bps.
S07[2] (BAUD) is the 1200 or 600 bps indicator.
BAUD = 1b will enable the 1200/600 V.23 channel to run
at 1200 bps while BAUD = 0b will enable 600 bps
operation.
When a V.23 connection is successfully est ab lish ed, the
modem will respond with a “c” character if the
connection is made with the modem transmitting at
1200/600 bps and receiving at 75 bps. The modem will
respond with a “v” character if a V.23 connection is
established with the modem transmitting at 75 bps and
receiving at 1200/600 bps.
The Si2400 supports the V.23 turnaround procedure.
This allows a modem that is transmitting at 75 bps to
initiate a “turnaround” procedure so that it can begin
transmitting data at 1200/600 bps and receiving data at
75 bps. The modem is defined as being in V.23 master
mode if it is transmitting at 75 bps and it is defined as
being in slave mode if the modem is transmitting at
1200/600 bps. The following paragraphs give a detailed
description of the V.23 turnaround procedure.
5.13.1. Modem in master mode
To perform a direct turnaround once a modem
connection is established, the master host goes into
online-command-mode by sending an escape
command (Escape pin activation, TIES, or ninth bit
escape) to the master modem. (Note that the host can
initiate a turnaround only if the Si2400 is the master.)
The host then sends the ATRO command to the Si2400
to initiate a V.23 turnaround and to go ba ck to the online
(data) mode.
The Si2400 will then change its carrier frequency (from
390 Hz to 1300 Hz), and wait to detect a 390 Hz carrier
for 440 ms. If the modem detects more than 40 ms of a
390 Hz carrier in a time window of 440 ms, it will echo
the “c” response character. If the modem does not
detect more than 40 ms of a 390 Hz carrier in a time
window of 440 ms, it will hang up and echo the “N” (no
carrier) char ac te r as a re spo n s e
Si2400
26 Rev. 1.3
5.13.2. Modem in slave mode
Configure GPIO4 as ALERT (S2E[7:6] [GPIO4] = 11b).
The Si2400 performs a reverse turnaround when it
detects a carrier drop longer than 20 ms. The Si2400
then reverses (it changes its carrier from 1300 Hz to
390 Hz) and waits to detect a 1300 Hz carrier for
220 ms. If the Si2400 detects more than 40 ms of a
1300 Hz carrier in a time window of 220 ms, then it will
set the ALERT pin (GPIO4) and the next character
echoed by the Si2400 will be a “v”.
If the Si2400 does not detect more than 40 ms of the
1300 Hz carrier in a time window of 220 ms, then it
reverses again and waits to detect a 390 Hz carrier for
220 ms. Then, if the Si2400 detects more than 40 ms of
a 390 Hz carrier in a time window of 220 ms, it will set
the ALERT pin (GPIO4) and the next character echoed
by the Si2400 will be a “c”.
At this point, if the Si2400 does not detect more than
40 ms of the 390 Hz carrier in a time windo w of 22 0 ms,
then it will hang up, set the ALERT pin (GPIO4), and the
next character echoed by the Si2400 will be an “N” (no
carrier).
Successful completion of a turnaround procedure in
either master or slave will automatically update
S07[4] (V23T) and S07[5] (V23R) to indicate the new
status of the V.23 connection.
In order to avoid using the ALERT pin, the host may
also be notified of the ALERT condition by using 9-bit
data mode. Setting S15[0] (NBE) = 1b and
S0C[3] (9BF) = 0b will configure the ninth bit on the
Si2400 TXD path to function exactly as the ALERT pin
has been describe d .
5.14. V.42 HDLC Mode
The Si2400 supports V.42 through hardware HDLC
framing in all modem data modes. Frame packing and
unpacking, including opening and closing flag
generation and detection, CRC computation and
checking, zero insertion and deletion, and modem data
transmission and reception are all performed by the
Si2400. V.42 error correction and V.42bis data
compression must be per fo rm e d by th e ho st.
The digital link interface in this mode uses the same
UART interface (8-Bit Data and 9-Bit Data formats) as in
the asynchronous modes and the ninth data bit may be
used as an escape by setting S15[0] (NBE) = 1b. When
using HDLC in 9-Bit Data mode, if the ninth bit is not
used as an escape, it is ignored.
To use the HDLC feature on the Si2400, the host must
first enable HDLC operation by setting
S07[7] (HDEN) = 1b. Next, the host may initiate the call
or answer the call using either the “ATDT#”, the “ATA”
command, or the auto-answer mode. (The auto-answer
mode is implemented by setting register S00 (NR) to a
non-zero value.) When the call is connected, a “c”, “d”,
or a “v” is echoed to the host controller. The host may
now send/receive data across the UART using either
the 8-Bit Data or 9-Bit Dat a formats with flow control.
At this point, the Si2400 will begin framing data into the
HDLC format. On the transmit side, if no data is
available from the host, the HDLC flag pattern is sent
repeatedly. When data is available, the Si2400
computes the CRC code throughout the frame and the
data is sent with the HDLC zero-bit insertion algorithm.
HDLC flow control operates in a similar manner to
normal asynchrono us flow contro l across the UART and
is shown in Figure 11. In order to operate flow control
(using the CTS pin to indicate when the Si2400 is ready
to accept a character), a DTE rate higher than the line
rate should be selected. The method of transmitting
HDLC frames is as follows:
1. After the call is connected, the host should begin sending
the frame data to the Si2400, using the CTS flow control to
ensure data synchronicity. A 1-deep character FIFO is
implemented in the Si2400 to ensure that data is always
available to transmit.
2. When the frame is complete, the host should simply stop
sending data to the Si2400. As shown in Figure 11B, since
the Si2400 does not yet recognize the end-of-frame, it will
expect an extra byte and assert CTS. If CTS is used to
cause a host interrupt, then this final interrupt should be
ignored by the host.
3. When the Si2400 is ready to send the next byte, if it has
not yet received any data from the host, it will recognize
this as an end-of-frame, raise CTS, calculate the final CRC
code, transmit the code, and begin transmitting stop flags.
4. After transmitting the first stop flag, the Si2400 will lower
CTS indicating that it is ready to receive the next frame
from the host. At this point the process repeats as in
step 1.
The method of receiving HDLC frames is as follows:
1. After the call is connected, the Si2400 searches for flag
data. Then, once the first non-flag word is detected, the
CRC is continuously computed, and the data is sent
across the UART (8-Bit Data or 9-Bit Data mode) to the
host after removing the HDLC zero-bit insertion. The DTE
rate of the host must be at least as high as that of data
transmission. HDLC mode only works with 8-bit data
words; the ninth bit is used only for escape on TXD and
End-of-Frame Received (EOFR) on RXD.
2. When the Si2400 detects the stop flag, it will send the last
data word in the frame as well as the two CRC bytes and
determine if the CRC checksum matches. Thus, the last
two bytes are not frame data, but are the CRC bytes,
which can be discarded by the host. If the checksum
matches, then the Si2400 echoes “G” (good). If the
Si2400
Rev. 1.3 27
checksum does not match, the Si2400 echoes “e” (error).
Additionally, if the Si2400 detects an abort (seven or more
contiguous ones), then it will echo an “A”.
When the “G”, “e”, or “A” (referred to as a frame result
word) is sent, the Si2400 raises the EOFR (end of frame
receive) pin (see Figure 10B). The GPIO1 pin must be
configured as EOFR by setting SE4[3] (GPE) = 1b. In
addition to using the EOFR pin to indicate that the byte is a
frame result word, if in 9-bit data mode (set S15[0] (NBE) =
1b), the ninth bit will be raised if the byte is a frame result
word. To program this mode, set S0C[3] (9 BF) = 1b and
SE0[3] (ND) = 1b.
3. When the next frame of data is detected, EOFR is lowered
and the process repeats at step 1.
To summarize, the host will begin receiving data
asynchronously from the Si2400. When each byte is
received, the host should check the EOFR pin (or the
ninth bit). If the EOFR pin (or the ninth bit) is low, then
the data is valid frame data. If the EOFR pin (or the
ninth bit) is high, then the data is a frame result word.
5.15. Fast Connect
In modem applications that require fast connection
times, it is possible to reduce the length of the
handshake.
If the Si2400 is set up as an answering modem, the
answer tone transmitted by the Si2400 may be
shortened by setting S1E (TATL) = 0x00 and setting
S34 (TASL) to the desired answer tone length. For the
most robust operation, it is recommended that the
answer tone sent by the answering modem be at least
10 msec (S34 (TASL) = 0x06).
If the Si2400 is configured as an originating modem,
setting the No Answer Tone bit (S33[1] [NAT] = 1b)
forces the Si2400 to recognize a short answer tone,
thereby reducing the overall connection sequence.
Additional modem handshaking control can be adjusted
through the registers shown in Table 15. These
registers are most useful if the user has control of both
the originat in g an d an sw er mod e ms .
Figure 11. HDLC Timing
B. Fram e Receive
A. Fram e T ransm it
TXD
RXD Start Stop
Start
Host begins frame N
Frame N StartStart Stop
Host finished sending frame N Host begins frame N + 1
CTS
Frame N + 1
CRC Byte 2 Stop
Stop Start Start StopReceive Data
EOFR
(or b it 9)
Si2400 ready for byte 1 of frame N
Note: Figure not to scale.
(CTS used as normal flow control.) Si2400 detects end of frame N.
Si2400 ready for byte 1
of frame N + 1.
CRC Byte 1 Frame Result Word
Si2400
28 Rev. 1.3
5.16. Clock Generation Subsystem
The Si2400 contains an on-chip clock generator. Using
a single master clock input, the Si2400 can generate all
modem sample rates necessary to support V.22bis,
V.22/Bell212A, and V.21/Bell103 standards and a
9.6 kHz rate for audio playback. Either a 4.9152 MHz
clock on XTALI or a 4.9152 MHz crystal across XTALI
and XTALO form the master clock for the Si2400. This
clock source is sent to an internal phase-locked loop
(PLL) which generates all necessary internal system
clocks. The PLL has a settling time of ~1 ms. Data on
RXD should not be sent to the device prior to settling of
the PLL.
The CLKOUT pin outputs a 78.6432 MHz/(N + 1) clock
which may be used to clock a microcontroller or other
devices in the system. N may be programmed via
SE1[4:0] (CLKD) to any value from 1 to 31. N defaults to
7 on power-up. CLKOUT is disabled by setting N = 0.
SE1[7:6] (MCKR) allows the user to control the
microcontroller clock rate. On powerup, the Si2400
UART DTE rate is set to 2400 bps, given that the clock
input is 4.9152 MHz. The MCKR register conserves
power via slower clocking of the microcontroller for
specific applications where power conservation is
required. Table 16 shows the configurations for different
values of MCKR.
Table 15. Handshaking Control Registers
Register Name Function Units Default
S1E TATL Transmit Answe r Tone Length 1 sec 0x03
S1F ATTD Answer Tone to Transmit Delay 5/3 msec 0x2D
S20 UNL Unscrambled Ones Length—V.22 5/3 msec 0x5D
S21 TSOD Transmit Scrambled Ones Delay—V.22 53.3 msec 0x09
S22 TSOL Transmit Scrambled Ones Length—V.22 5/3 msec 0xA2
S23 VDDL V.22/22b Data Delay Low 5/3 msec 0xCB
S24 VDDH V.22/22b Data Delay High (25 6) 5/3 msec 0x08
S25 SPTL S1 Pattern Time Length V.22b 5/3 msec 0x3C
S26 VTSO V.22b 1200 bps Scrambled Ones Length 53.3 msec 0x0C
S27 VTSOL V.22b 2400 bps Scrambled Ones Length Low 5/3 msec 0x78
S28 VTSOH V.22b 2400 bps Scrambled Ones Length High (256) 5/3 msec 0x08
S2A RSO Receive Scrambled Ones V.22b Length 5/3 msec 0xD2
S2F FCD FSK Connection Delay Low 5/3 msec 0x3C
S30 FCDH F SK Con n ec tio n Dela y High (256) 5/3 msec 0x00
S31 RATL Receive Answer Tone Length 5/3 msec 0x3C
S34 TASL Answer Tone Length (only used in S1E [TATL] = 0x00) 5/3 msec 0x5A
S35 RSOL Receive V.22 Scrambled Ones Length 5/3 msec 0xA2
Table 16. MCKR Configurations
SE1[7:6]
(MCKR) Controller
Clock (MHz) Modes
0 0 9.8304 MHz All (default)
0 1 4.9152 MHz All except V.22bis,
PCM
1 0 2.4576 MHz Command only
1 1 Reserved Reserve d
Si2400
Rev. 1.3 29
6. AT Command Set
The controller provides several vital functions including
AT command parsing, DAA control, connect sequence
control, DCE protocol control, intrusion detection,
parallel phone off-hook detection, escape control, caller
ID control and formatting, PCM mode control, ring
detect, DTMF control, call progress monitoring, and
HDLC framing. The controller also writes to the control
registers that configure the modem. Virtually all
interaction between the h ost and the mode m is done via
the controller. The controller uses AT (ATtention)
commands and S-Registers to con figur e and con trol th e
modem.
The modem has two basic modes of operation, the
Command mode and the Data mode. The Si2400 is
asynchronous in both the Comma nd mode and the Dat a
mode. The modem is in the Command mode at power-
up, after a reset, before a connection is made, after a
connection is dropped, and during a connection after
successfully “Escaping” from the data mode back to the
command mode using one of the methods previously
described. The following section describes the AT
command set available in the Command mode.
The Si2400 supports a subset of the typical modem AT
command set since it is intended for use with a
dedicated microcontroller instead of general terminal
applications. AT commands begin with the letters AT
and are followed directly (no space) by the command.
(These commands are also case-sensitive.) All AT
commands must be entered in upper case including AT
except w##, r#, m# , q# , an d z (wa k e up-o n -rin g ).
AT commands can be divided into two groups, control
commands and configuration commands. Control
commands, such as ATD, cause the modem to perform
an action (going off-hook and dialing). The value of this
type of command is changed at a particular time to
perform a particular action. For example, the command
“ATDT1234<CR>” will cause the modem to go off-hook
and dial the number 1234 via DTMF. This action will
exist only during a connection attempt. No enduring
change in the modem configuration will exist after the
connection or connection attempt has ended.
Configuration commands change modem
characteristics until they are modified or reversed by a
subsequent configuration command or the modem is
reset. Modem configuration status can be determined
with the use of “ATSR?<CR>” Where R is the two
character hexadecimal address of an S-register.
A command line is defined as a string of characters
starting with AT and ending with an end-of-line
character, <CR> (13 decimal). Command lines may
contain several commands, one after the other. If there
are no characters between AT and <CR>, the modem
responds with “O” after the carriage return.
6.1. Command Line Execution
The characters in a command line are executed one at
a time. Unexpected command characters will be
ignored, but unexpected data characters may be
interpreted incorrectly.
After the modem has executed a command line, the
result code corresponding to the last command
executed is returned to the terminal or host. In addition
to the “ATH” and “ATZ” commands, the commands
which warrant a response (e.g., “ATSR?” or “ATI”) must
be the last in the string and followed by a <CR>. All
other comm ands may be co ncatenat ed on a single line.
To echo command line characters, set the Si2400 to
echo mode using th e E1 co mm a nd .
All numeric argument s, including S-registe r address and
value, are in hexidecimal format and two digits must
always be entered.
6.2. < CR > End Of Line Character
This character is typed to end a command line. The
value of the <CR> character is 13 decimal, the ASCII
carriage return character. When the <CR> character is
entered, the modem executes the commands in the
command line. Commands which do not require a
response are executed immediately and do not
need a <CR>.
Table 17. AT Command Set Summary
Command Function
A Answer line immediately with modem.
DT# Tone dial number.
DP# Pulse dial number.
E Local echo on/off.
H Hangup/go on line.
I Chip revision.
M Speaker control options.
O Return online.
RO V.23 reverse.
S Read/write S-Registers.
w## Write S-Register in binary.
r# Read S-Register in binary.
m# Monitor S-Register in binary.
q# Read S-Register in binary.
Z Software reset.
z Wakeup on ring.
Si2400
30 Rev. 1.3
6.3. AT Command Set Description
AAnswer
The “A” command makes the modem go off hook and
respond to an incoming call. This command is to be
executed after the Si2400 has indicated a ring has
occurred. (The Si2400 will indicate an incoming ring by
echoing an “R”.)
This command is aborted if any other character is
transmitted to the Si2400 before the answer process is
completed.
Auto answer mode is entered by setting S00 (NR) to a
non-zero value. NR indica tes th e number of r ings before
answering the line.
Upon answering, the modem communicates by
whatever protocol has been determined via the modem
control registers in S07 (MF1).
If no transmit carrier signal is received from the calling
modem within the time specified in S39 (CDT), the
modem hangs up and enters the idle state.
DDial
DT# Tone Dial Number.
DP# Pulse Dial Number.
The D commands make the modem dial a telephone
call according to the digits and dial modifiers in the dial
string following the command. A maximum of 64 digit s is
allowed. A DT command performs tone dialing, and a
DP command performs pulse dialing .
The “ATS07=40DT;” command can be used to go off
hook without detecting di al tone or dialing.
The dial string must co nt ain only the digit s “ 0–9”, “*”, “#”,
“A”, “B”, “C”, “D”, or the modifiers “;”, “/”, or “,”. Other
characters will be interpreted incorrectly. The modifier
“,” causes a two second delay (added to the spacing
value in S04) in dialing. The modifier “/” causes a
125 ms delay (added to the spacing value in S04) in
dialing. The m odifier “;” returns the device to command
mode after dialing and must be the last character.
If any character is received by the Si2400 between the
ATDT#<CR> (or ATDP#<CR>) command and when the
connection is made (“c” or “d” is echoed), the extra
character is interpreted as an abort, and the Si2400
returns to command mode, ready to accept AT
commands. A line feed character immediately following
the <CR> will be treated as an “extra character” and will
abort the call.
If the modem does not ha ve to dial ( i.e., “ATDT<CR>” or
“ATDP<CR>” with no dial string), the Si2400 assumes
the call was manually established and attempts to make
a connection.
The following may be used to perform a hook-flash:
ATDT;
ATH
ATDT#
The length of the flash is determined by how quickly the
commands are entered. No comma is necessary for the
second dial because ATS01 sets the number of
seconds before dialing. Set S07[6] (BD) for blind dial.
6.3.1. Automatic Tone/Pulse Dialing
The Si2400 can be set up to try DTMF dialing and
automatically revert to pulse dialing if it determines that
the line is not DTMF-capable. This feature is best
explained by the following example:
If it is desired that the telephone number 12345 be
dialed, it is normally accomplished through either the
ATDT12345 or the ATDP12345 command. In the force
pulse dialing mode of operation, the following string
should be issued instead:
ATDT1,p12345
If the result code returned is “t,”, it indicates that the
dialing was accomplished using DTMF dialing. If the
result code returned is “tt,”, it indicates that the dialing
was accomplished using pulse dialing.
In the above example, the Si2400 dials the first digit “1”
using DTMF dialing. The “,” is used to pause in order to
ensure that the ce ntra l office has had time to accept the
DTMF digit “1”. When the Si2400 processes the “p”
command, it attempts to detect a dial tone. If a dial tone
is detected, the DTMF digit “1” was not effective, hence
the line does not support DTMF dialing. Conversely, if
the dial tone is not detected, the DTMF digit “1” was
effective, and the line does support DTMF dialing. The
character after the “p” may or may not be dialed,
depending on whether the DTMF digit “1” was effective
or not. If the “1” was effective (DTMF mode), the
character after the “p” is skipped. The next DTMF digit
to be dialed is “2”. Subsequent digits are all DT MF. If the
“1” was not effective, the first character after the “p” (the
“1”) is pulse dialed, and subsequent digits are all pulse
dialed.
E Command Mode Echo
Tells the Si2400 whether or not to echo characters sent
from the terminal.
EO
Does not echo characte rs sent from the terminal.
E1
Echo characters sent from the terminal.
H Hangup
Hang up and go into command mo de (go offline).
I Chip Identification
Si2400
Rev. 1.3 31
This command causes the modem to echo the chip
revision for the Si2400 device.
0 = Revision A
1 = Revision B
2 = Revision C, etc.
M Speaker On/Off Options
These options are used to control AOUT for use with a
call progress monitor speaker.
M0
Speaker always off.
M1
Speaker on until carrier established. The modem sets
SF4[3:2] (ARL) = 11b and SF4[1:0] (ATL) = 11b after a
connection is established.
M2
Speaker always on.
M3
Speaker on after last digit dialed, off at carrier detect.
O Return to Online Mode
This command returns the modem to the online mode. It
is frequently used after an escape sequence to resume
communicat ion with th e re mo te mode m .
RO Turn-Around
This command initiates a V.23 “direct turnaround”
sequence and returns online.
6.4. S-Register Control
S-registers control Si2400 configuration and provide
status information. Therefore, writing to and reading
from S-registers is central to the operation of the
modem. There are two fundamental methods for writing
to and reading from Si2400 S-Registers. The first and
most common method uses the ATSR=N and ATSR?
commands. These commands are used by
communication software packages and are universally
supported by modem chips. The second method uses
the ATw##, ATr#, ATm#, and ATq# commands and is
designed to reduce data flow and streamline
performance in embedded systems. When ATSR
commands are used, each character of the two
character hexadecimal values for both R and N are sent
to the AT command parser for decoding and action
immediately instead of waiting for a <CR>. Additionally,
a carriage return, <CR>, is required to terminate the
ATSR? command (not ATSR=N). When the #
commands are used, # is the single character ASCII
equivalent of the two character hexadecimal S-Register
address or value and no carriage return is required for
any of the # commands. Further explanations and
examples are given below.
6.4.1. ATSR Commands
The ATSR commands are generally used to write to or
read from S-registe rs. The address, R, and the value, N,
must be written into the AT command as a two character
hexadecimal value between 00 and FF. An S-Regi ster is
written with the command “ATSR=N”. The hexadecimal
address and value parameters appearing on the
terminal or PC screen are actually transmitted to the
modem as the hexadecimal equivalents of each
character. Likewise, the value N stored in S-register R is
read back to the terminal with the ATSR? command as
two hexadecimal characters. For example, read the
value of S35 after the Si2400 has been reset.
6.4.2. # Commands
The # commands offer several performance and
convenience advantages for embedded applications
over the more traditional ATSR-style commands. The #
parameter is entered as the ASCII equivalent of a
hexadecimal value representing the S-register address
or content. This parameter is sent to the mode m as the
hexadecimal equivalent of the ASCII value. The #
commands offer a more rapid method for reading and
writing S-Registers since fewer characters are sent to or
received from the modem.
6.4.3. w## Write S-Register
This command is analogous to the ATSR=N command.
From a terminal, the first # following w is the ASCII
equivalent of the hexadecimal address of the S-Register
and the second # is the ASCII equivalent of the
hexadecimal value of the S-Regi ster. For example, write
the value 58h to S34.
6.4.4. r# Command Read S-Register
This command is analogous to the ATSR? command.
From a terminal, the # following r is the ASCII
equivalent of the hexadecimal address of the S-
Register. The modem will echo the register contents as
the ASCII equivalent of the hexadecimal value of the
contents. This command executes immediately and
does not require a carriage return. Modem result codes
Terminal
Entry Sent to Modem Res ponse Display
ATS35?<CR> 41 54 53 33 35
3F 0D 41 32 A2
Terminal
Entry Sent to Modem
(hex) Response Display
ATw4X 41 54 77 34 58 — —
Si2400
32 Rev. 1.3
must be disabled by setting S14[7] (MRCD) = 1b when
using this command to ensure the host does not
confuse a result code with data. w## and r# are not
required to be on separate lines (no <CR> between
them). Once a <CR> is encountered, AT is required to
begin the next AT command. For example, write the
value 58h to S34 and read it back using # commands
and ATSR commands.
The economy of the # commands is clearly e v ident fro m
this example. One caveat when using the # commands
is that the ASCII equivalents of the response can be
displayed as special or graphic characters when using a
terminal emulator program such as HyperTerminal.
However, in an embedded system, it is easy to send
non-ASCII characters.
6.4.5. m# Command Monitor S-Register
This command is similar to the r# command but is
repeated at the DTE rate until a new byte is transmitted
to the modem. The modem will echo the register
contents to the display as the ASCII equivalent of the
hexadecimal value of the contents. This command
executes immediately and does not require a carriage
return. Modem result codes must be disabled by setting
S14[7] (MRCD) = 1b when using this command to
ensure that the host does not confuse a result code with
data.
6.4.6. q# Command Read S-Register with 0x5500
Offset
This command is the same as the r# command except
that the response from the Si2400 is formatted as the
hexadecimal value 0x55aa wher e aa is the hexade cimal
value of the S-register contents. From a terminal, the #
following q is the ASCII equivalent of the hexadecimal
address of the S-register. This command executes
immediately and does not require a carriage return. The
0x5500 offset in the value of the register contents
prevents confusion between data and result codes and
permits the result codes to remain enabled.
Z Software Reset (upper-case Z)
The “Z” command causes a software reset to occur in
the device whereby the registers will return to their
default power up value with the exception of E0, E2,
E4–E7, F8, and F9. These registers are not reset, so
the Si2400 will maintain its current DTE settings, GPIO
definitions, tone detect and transmit settings, and
overload and billing tone detection status. The hardware
reset pin, RESET (Si2400, pin 8), is used to reset the
Si2400 to factory default settings. If other commands
follow on the same line, another AT is needed after the
“Z” (e.g., ATZATS07=06<CR>).
z Wakeup on Ring (lower-case z)
The Si2400 en ters a low-power m ode wherein the DSP
and microcontroller are powered down. The serial
interface also stops functioning. In this mode, only the
line-side chip (Si3015) and the communication link
function. An incoming ring signal or line transient
causes the Si2400 to power up and echo an “R”.
Without a ring signal, the host must perform a hardware
reset (Si2400, pin 8) to power up the Si2400. Return
from wake-on-ring can also be set to trigger the ALERT
pin by setting S62[4] (WOR) = 1b.
6.5. Alarm Industry AT Commands
The Si2400 supports a complete set of commands
necessary for making connections in security industry
systems. The Si2400 is configurable in three modes for
these applications. The first mode, DTMF send and
receive, is selected with the “!1” command. The second
mode uses FSK transmit with a tone acknowledgement
and is selected with “!2”. Finally, “!7” is selected for the
tone-on/tone-off mode.
The following are a few general comments about the
use of “!” commands. Specific details for each command
is given below. The first instance of the “!” must be on
the same line as the ATDT or ATDP command. DRT
must be set to data mode (SE4[5:4] (DRT) = 0b) before
attempting to send tone s af ter a “!” comm and. Th e three
data-mode escape sequences (“+++”, “escape” pin and
“ninth-bit”) only function in “!2” mode. However, using
the “+++” or “ninth-bit” is not recommended because
characters could be sent to and misinterpreted by the
remote modem. Only the “escape pin” (Si2400, pin 14)
is recommended for use in the “!2” mode. The “!1” and
“!7” modes have spec ial esca pe provisio ns descr ibed in
their respective sections below. The AT commands for
Alarm Industry applications are described in Table 18.
Terminal
Entry Sent to
Modem (hex) Response
(hex) Display
ATw4Xr4 41 54 77 3 4 58
72 34 58 X
ATS34=58S34
?<CR> 41 54 53 33 34
3D 35 38 53 33
34 3F 0D
35 38 58
Si2400
Rev. 1.3 33
6.5.1. A0
Answer and tr ansmit the AIN an alog input sign al on the
telephone line and connect the phone line receive
signal to the AOUT pin (see Figure 10B). This mode
also monitors for local DTMF received signals and user
defined tones. Any received character is echoed. User-
defined tones are echoed as X and Y. Transmission of
any data to the Si2400 UART will cause the modem to
go into the command mode. The modem can then send
DTMF tones via the “ATDT #!0” command (where #
represents a DTMF character 0-9, A-D, # or*) or be
disconnected with the “ATH” command. The “ATDT #!0”
command string does not initiate a new call since the
modem is already connected.
Notes:
1. DRT must be set to data mode (SE4[5:4](DRT) = 00b)
before attempting to send tones after a “A0” command.
User defined tones are enabled by setting S14[6]
(UDF) = 1b and require DSP low-level control as
defined on page 40. The online mode can be resumed
by issuing the “ATO” command. (see the “!0” section
for more detail).
2. DTMF detection is only intended for local detection
of a parallel device.
6.5.2. !0
After dialing the number , go to DTMF monitor mode with
no modem connection. After dialing the !0 mode is the
same as the A0 mode described previo usly.
Example: Dial a number and detect DTMF tones in
“data mode.”
Example: Dial a number and place the Si2400 in “voice
mode.”
DTMF detection is only intended for local detection of a
parallel device, not for detection of a remote source
over two local loops. “Data mode” (see example above)
DTMF detection is reliable on a quiet line without the
presence of interfering audio signals or voice. DTMF
detection, although possible, in the “voice mode” (see
example above) is not recommended and can be
unreliable.
6.5.3. !1
Dial number and follow the DTMF security protocol.
The format for this command is as follows:
ATDT<phone number>!1<message 1><CR>
K
!<message 2><CR>
K
Table 18. AT Command Set Extensions
for Alarm Industry
Command Function
A0 Answer and switch to DTMF monitor
mode
A1 Answer and switch to “SIA Format”
!0 Dial and switch to DTMF monitor
mode
!1 Dial and switch to DTMF security
mode
!2 Dial and switch to “SIA Format”
!7 Dial and switch to pulse security mode
X1 SIA half-duplex mode search
X2 SIA half-duplex return online as
transmitter
X3 SIA half-duplex return online as
receiver
Command Result
ATDT#!0<CR>
After “,” result code Dials #
ATSE4=00O<CR> Detects DTMF tones in
“data mode”
ATDT1234!0
After “,” result code Sends DTMF tones for
1234
ATSE4=00O<CR> Detects DTMF tones in
“data mode”
ATH Terminates call
Command Result
ATSEf=02 Powers ADC and DAC
ATSE2=02 Sets GPIO1 as analog inpu t
ATDT#!0<CR>
After “,” result code Dials #
Modem in “voice mode”
Audio placed on Ain
(GPIO1) is transmitted and
received audio is available
on AOUT (see Figure 10).
ATH Terminates call
ATSE4=02 Returns Si2400 to “data
mode” for next dial com-
mand.
Si2400
34 Rev. 1.3
!<message 3><CR>
K
.
.
.
K
!<message n><CR>
The modem dials the phone number and echoes “r”
(ring), “b” (busy), and “c” (connect) as appropriate. “c”
echoes only after the Si2400 detects the Handshake
Tone. After a 250 msec delay, the modem sends the
DTMF tones containing the first message data and
listens for a Kissoff Tone. If the Kissoff Tone is shorter
than or equal to the value stored in S36(KTL)
(default = 480 ms) is detected, the Si2400 echoes a “K”.
A “k” is echoed if the length of the Kissoff Tone is longer
than the S36(KTL) value. The controller can then send
the next message. All messages must be pre ceded by a
“!” and followed by a <CR> and received by the Si2400
within 250 msec after the “K” is echoed. Setting
S0C[0] (MCH) = 1b causes a “.” to be echoed when the
DTMF tone is turned on and a “/” character to be
echoed when the DTMF tone is turned off. This can help
the host monitor the status of the message being sent.
The previous message can be resent if the host
responds with a “~” after the Si2400 echoes a “K”. Any
character other than a “!” or a “~” sent to the modem
immediately after the “K” will cause the modem to
escape to the command mode and remain off-hook. Any
character except “!” and “~” sent during the transmission
of a message will cause the message to be aborted and
the modem to return to the command mode.
If the Kissoff Tone is not received within 1.25 seconds,
the modem will echo a “^”. A “~” from the host will cause
the last message to be resent. Any character other than
a “!” or a “~” sent to the modem imme diately after the “^”
will cause the modem to escape to the command mode
and remain off-hook . After hanging up, set SC C = 00 to
ensure that a subsequent automatic answer (e.g.
500 = 01) or Bellcore CID will function normally.
6.5.4. A1
Answers a call and follows the “SIA Format” protocol for
Alarm System Communications at 300 bps (see !2).
6.5.5. !2
Dial number and follow the “SIA Format” protocol for
Alarm System Communications.
The modem dials the phone number and echoes “r”
(ring), “b” (busy), and “c” (connect) as appropriate. “c”
echoes only after the Si2400 detects the Handshake
Tone and the speed synchronization signal is sent. The
signaling is at 300 bps half-duplex FSK. The host can
send the first SIA block after the “c” is received. Once
the block is transmitted, the modem can monitor for the
acknowledge tone by completing the following
sequence:
1. Place the Si2400 in the command mode by pulsing the
ESCAPE pin (Si2400 pin 14). The “+++” and “ninth-bit”
escape modes will operate in the “!2” mode but are not
recommended because they can send unwanted
characters to the remote modem.
2. Issue the “ATX1” command to turn the modem transmitter
off and begin monitoring for the acknowledgment tones.
3. Monitor for a positive (negative) acknowledgment “P” (“N”)
after the tone has been detected for at least 400 msec.
4. The modem, still in command mode, can be placed online
as a transmitter by issuing the “ATX2” comman d or a
receiver by issuing the “ATX3” command. If tonal
acknowledgement is not used, the host can tog gl e the
ESCAPE pin to place the Si2400 in the command mode
and issue an “ATX2” or an “ATX3” command to reverse
data direction.
This sequence can be repeated for long messages.
6.5.6. !7
The “!7” mode is a field-configurable tone-on/tone-off
messaging protocol for the alarm industry. There are
many proprietary standards that necessitate a flexible
alarm protocol. The “!7” command fills that need with
programmabl e usage and timing.
The “!7” mode is entered by issuing the “ATDT<phone
number>!7<message><CR> After the Si2400 connects
to the alarm receiver, it waits for a Handshake Tone
(equivalent to an answer tone). When a valid
Handshake Tone is received a “c” (connect) is echoed
to the host and the message is sent. The Si2400
echoes a “,” to the host signaling the message is sent,
additional messages can be received from the host and
to mark the start of the intermessage time. The end of
the intermessage time is marked by the “N” result code.
The Si2400 monitors for the Kissoff Tone from the alarm
receiver which acknowledges receipt of the message.
The Si2400 echoes a “K” to indicate the Kissoff Tone
was received or a “^” to indicate it has not been
received prior to the timeout set by S36[3:2] (IDKT).
Register S36 is reconfigured from SKDTL (Second
Kissoff Tone Detector Length) as used in A1 and !1
modes to Alarm 1, a bit-mapped register, in the “!7”
mode. Register S1F is reco nfigu red from ATTD (Answer
Tone to Transmit Delay) to Alarm3, a bit-mapped
register, in the “!7” mode. S38(Alarm 2) is a bit-mapped
register only used in “!7” mode. The following is a
summary of commands, result codes and S-Registers
encountered in the “!7” mode. After hanging up, set
SCC = 00 to ensure that a subsequent automatic
Si2400
Rev. 1.3 35
answer (e.g. 500 = 01) or Bellcore CID will function
normally.
Basic Command
ATDT<phone number>!7<tone pulse digits 0-9, B-
F><CR>
Result codes after dialing
t Dial tone detected
, Phone number dialed—start of initial
intermessage time
r Ringback tone detected
b Busy tone detected
c Handshake Tone detected in S39 (CDT)
time window and present for S38[4:2]
(HMT) msec
N Handshake Tone not detected per above
Result codes after “c” received
, Message sen t— start of inter m ess ag e time
K Kissoff Tone detected in S36[3:2] (IDKT)
time window and present for S38[4:2] (HMT)
msec
^ Kissoff Tone not detected per above
N Intermessage timeout defined in S36[3:2]
(IDKT) elapsed. A second message received
after the “,” is sent at this time.
Table 19. !7 Parameters
S-Register Bits Name Function
S1F Alarm 3 Reconfigured from ATTD in !7 mode.
7:5 KOT Kissoff timeout.
4:0 IMT Intermessage timing.
S2B 7:0 DTL Reconfigured from DTL in !7 mode to pulse on time (5/3 ms units).
S2C 7:0 DTTO Reconfigured from DTTO in !7 mode to pulse off time (5/3 ms units).
S2D 7:0 SDL Reconfigured from SDL in !7 mode to pulse interdigit time (5/3 ms units).
S2E 7:0 RTCT Reconfigured from RTLT in !7 mode to handshake end to data TX delay
(10 ms units).
S36 Alarm 1 Reconfigured from SKDTL in !7 mode.
7:6 POF Pulse off time.
5:4 PON Pulse on time.
3:2 IDKT Intermessage delay and Kissoff timeout.
1:0 IT Interdig i t tim ing .
S38 Alarm 2 Only used in !7 mode.
7 DBD Delay before data.
6:5 DCF Data carrier frequency.
4:2 HMT Handshake minimum tone.
1:0 HF Handshake frequen cy.
S39 7:0 CDT Reconfigured from CDT in !7 mode to handshake tone timeout.
Si2400
36 Rev. 1.3
6.5.7. Intermessage Timing
Intermessage timing is accomplished in three ways,
relative to the end of the previous message (“,” result
code), relative to the Kissoff Tone (“K” result code) or
relative to the Kissoff timeout (“^” result code).
If the intermessage timing is relative to the end of the
previous message (S36[3:2] [IDKT] = 10bor 11b), the
intermessage timer begins with the “,” result code. The
Si2400 sends an “N” to mark the time in which the
intermessage timer has timed out. If another message
is received prior to the “N”, the Si2400 keeps the
message and sends it to the receiver at the time the “N”
is sent.
If a message is not received within the time frame
defined by “,” and “N”, the Si2400 sends nothing, waits
for the next message and transmits the message as
soon as the host sends the message. This message
may not be accepted by the alarm receiver.
If the intermessage timing is relative to the end of the
Kissoff Tone, the timing begins when the “K” result code
is sent. In the event a kissoff tone was not detected, the
intermessage timing begins when the “^” is sent.
6.5.8. Returning to Command Mode
To return to command mode, the host sends any
character except the “~” and “!” characters. The
example here uses a <CR> to escape.
Once in command mode, all of the AT commands are
available.
ATH<CR> Is used to hang up the line. Note that it is
the responsibility of the host to hang up the
line.
!7xxx<CR> Sends the message xxx without dialing.
The message is sent as soon as the
Si2400 receives the <CR>. After this
message, it is again possible to send
subsequent messages using the “~” and “!”
commands shown above.
X1
Search for positive and negative acknowledge tones in
SIA half-duplex 300 bps mode. The Si2400 will respond
with “P” when a positive acknowledge is detected and
“N” when a negative ackno wle dge is detected.
X2
Return to online mode in SIA half-duplex mode as
transmitter.
X3
Return to online mode in SIA half-duplex mode as
receiver.
Figure 12. !7 Security Timing
S39 (CDT )
B e fore give up o n
handshake f = S 38[1:0] (HF)
min.
min.
2nd Mes sage
S36[1:0] (IT) = 0Xb
Interdigit
S36[1:0] (IT) = 1Xb
Interdigit
Handshake
Tone Kissoff
Tone
S36[3:2] (IDK T)
B efo re Ind ica ting lac k
of Kissoff
1st
Digit Last
Digit 1st
Digit Last
Digit
S36[3:2] (IDK T) =
1Xb
Intermes sage from end of previous
m ess age to start of next mes sage
In tra d ig it T imin g
Pulse On = S36[5:4] (PON )
Pulse Off = S36[7:6] (POF )
Pulse freq = S38[6:5] (DCF)
S36[3:2] (IDK T) = 0Xb Interm essag e
From end of Kissoff Tone
S38[7] (DB D)
S38[4:2] (HMT )
f = S38[6:5] (DC F)
S38[4:2] (HMT)
Si2400
Rev. 1.3 37
6.6. Modem Result Codes and Call
Progress
Table 20 shows the modem result codes which can be
used in call progress monitoring. All result codes are a
single character to speed up communication and ease
host processing.
6.6.1. Automatic Call Progress Detection
The Si2400 has the ability to detect dial, busy and
ringback tones automatically. The following is a
description of the algorithms that have been
implemented for th ese three tones.
1. Dial Tone. The dial tone detector looks for a dial tone after
going off hook and before dialing is initiated. This can be
bypassed by enabling blind dialing (set S07[6] (BD) =1b).
After going off hook, the Si2400 waits the number of
seconds in S01 (DW) before searching for the dial tone.
In order for a dial tone to be detected, it must be present
for the length of time programmed in S1C (DTT). Once the
dial tone is detected, dialing will comme nce. If a dial tone
is not detected within the time programmed in S02 (CW),
the Si2400 will hangup and echo an “N” to the user.
2. Busy / Ringback Tone. After dialing has completed, the
Si2400 monitors for Busy/Ringback and modem answer
tones. The busy and ringback tone detectors both use the
call progress energy detector. The registers that set the
cadence for busy and ringback are listed in Table 21.
Si2400 register settings for globa l cadences for busy and
ringback tones are listed in Table 22.
6.6.2. Manual Call Progress Detection
Because other call progress tones beyond those
described above may exist, the Si2 400 support s ma nual
call progress. This requires the host to read and write
the low-level DSP registers and may require realtime
control by the host. Manual call progress may be
required for detection of application-specific ringback,
dial tone, and busy signals. The section on DSP low
level control should be read before attempting manual
call progress detection.
To use this mode, the automatic modem responses
should be disabled by setting S14[7] (MRCD) = 1b. The
call progress biquad filters can be programmed to have
a custom frequency response and detection level (as
described in “Low Level DSP Control”).
Four dedicated user-defined frequency detectors can
Table 20. Modem Result Codes
Command Function
a British Telecom Caller ID Idle Tone
Alert Detected
b Busy Tone Detected
c Connect
d Connect 1200 bps (when pro-
grammed as V.22bis modem)
f Hookswitch Flash or Battery Reversal
Detected
H Modem Automatically Hanging Up in
Japan Caller ID Mode
IIntrusion Completed (parallel phone
back on hook)
i Intrusion Detected (parallel phone off-
hook on the line)
K Kissoff Tone Detected
k Contact ID Kissoff Tone too long.
L Phone Line Detected
l No Phone Line Detected
m Caller ID Mark Signal Detected
NNo Carrier Detected
n No Dial tone (time-out set by CW
[S02])
O Modem OK Res po n se
R Incoming Ring Signal Detected
r Ringback Tone Detected
t Dial Tone
v Connect 75 bps TX (V.23 originate
only)
x Overcurre nt State De tected After an
Off-Hook Event
^ Kissoff tone detection required
, Dialing Complete
Table 21. Busy and Ringback Cadence
Registers
Register Name Function Units
S16 BTON Busy tone on time 10 msec
S17 BTOF Busy tone off time 10 msec
S18 BTOD Busy tone delta time 10 msec
S19 RTON Ringback tone on
time 53.333
msec
S1A RTOF Ringback tone off
time 53.333
msec
S1B RTOD Ringback tone delta
time 53.333
msec
Si2400
38 Rev. 1.3
be programmed to search for individual tones. The four
detectors have center frequencies which can be set by
registers UDFD1–4 (see Table 24). (SE5[6] [TDET]
[SE8 = 0x02] Read Only Definition) can be monitored,
along with TONE, to detect energy at these user-
defined frequencies. The default trip-threshold for
UDFD1–4 is –34 dBm but can be modified with the DSP
register UDFSL.
By issuing the “ATDT;” command, the modem will go off
hook and return to command mode. The user can then
put the DSP into call progress monitoring by first setting
SE8 = 0x02. Next, set SE5 (DSP2) = 0x00 so no tones
are transmitted, and set SE6 (DSP3) to the appropriate
code, depending on which types of tones are to be
detected.
Table 22. Si2400 Global Ringer and Busy Tone Cadence Settings
Country RTON RTOF RTOD BTON BTOF BTOD
S19 S1A S1B S16 S17 S18
Australia 0x07 0x03 0x01 0x25 0x25 0x04
Austria 0x12 0x5D 0x0A 0x1E 0x1E 0x03
Belgium 0x12 0x38 0x06 0x32 0x32 0x05
Brazil 0x12 0x4B 0x08 0x19 0x19 0x03
Bulgaria 0x12 0x4B 0x08 0x14 0x32 0x05
China 0x12 0x4B 0x08 0x23 0x23 0x04
Cyprus 0x1C 0x38 0x06 0x32 0x32 0x05
Czech Republic 0x12 0x4B 0x08 0x18 0x24 0x0A
Denmark 0x0E 0x8C 0x0F 0x19 0x19 0x03
Finland 0x0E 0x5D 0x0A 0x1E 0x1E 0x03
France 0x1C 0x41 0x07 0x32 0x32 0x05
Germany 0x12 0x4B 0x08 0x32 0x32 0x05
Great Britain 0x07 0x03 0x01 0x25 0x25 0x04
Greece 0x12 0x4B 0x08 0x1E 0x1E 0x03
Hong Kong, New Zealand 0x07 0x03 0x01 0x32 0x32 0x05
Hungary 0x17 0x46 0x0F 0x1E 0x1E 0x03
Iceland 0x16 0x58 0x09 0x19 0x19 0x03
India 0x07 0x03 0x01 0x4B 0x4B 0x08
Ireland 0x07 0x03 0x01 0x32 0x32 0x05
Italy, Netherlan ds, Norway , Thail and,
Switzerland, Israel 0x12 0x4B 0x08 0x32 0x32 0x05
Japan, Korea 0x12 0x25 0x04 0x32 0x32 0x05
Luxembourg 0x12 0x4B 0x08 0x30 0x30 0x05
Malaysia 0x07 0x03 0x01 0x23 0x41 0x07
Malta 0x00 0x00 0x00 0x00 0x00 0x00
Mexico 0x12 0x4B 0x08 0x19 0x19 0x03
Poland 0x12 0x4B 0x10 0x32 0x32 0x05
Portugal 0x12 0x5D 0x0A 0x32 0x32 0x05
Singapore 0x07 0x03 0x01 0x4B 0x4B 0x08
Spain 0x1C 0x38 0x06 0x14 0x14 0x02
Sweden 0x12 0x5D 0x0A 0x19 0x19 0x03
Taiwan 0x12 0x25 0x04 0x32 0x32 0x05
U.S., Canada (defau lt) 0x25 0x4B 0x08 0x32 0x32 0x05
Si2400
Rev. 1.3 39
At this point, users may program their own algorithm to
monitor the detected tones. If the host wishes to dial, it
should do so by blind dialing, setting the dial timeout
S01 (DW) to 0 seconds, and issuing an
“ATDT<Phone Number><CR>;” command. This will
immediately dial and return to command mode.
Once the host has detected an answer tone using
manual call progress, the host should immediately
execute the “ATDT” command in order to make a
connection. This will cause the Si2400 to search for the
modem answer tone and begin the correct connect
sequence.
In manual call progress, the DSP can be programmed
to detect specific tones. The result of the detection is
reported into SE5 (SE8 = 0x2) as explained above. The
output is priority encoded such that if multiple tones are
detected, the one with the highest priority whose
detection is also enabled is r eported (see SE5 [SE8 =02]
Read Only.)
In manual call progress, the DSP can be programmed
to generate specific tones (see SE5[2:0] (TONC)
(SE8 = 02) Write Only). For example, setting
SE5[2:0] (TONC) = 110b will generate the user-defined
tone as indicated by UFRQ in Table 24 with an
amplitude of TGNL.
Table 23 shows the mappings of Si2400 DTMF values,
keyboard equivalents, and the related dual tones.
Table 23. DTMF
DTMF
Code Keyboard
Equivalent
Contact
ID
Digit
Tones
Low High
0 0 0 941 1336
1 1 1 697 1209
2 2 2 697 1336
3 3 3 697 1477
4 4 4 770 1209
5 5 5 770 1336
6 6 6 770 1477
7 7 7 852 1209
8 8 8 852 1336
9 9 9 852 1477
10 D – 941 1633
11 * B 941 1209
12 # C 941 1477
13 A D 697 1633
14 B E 770 1633
15 C F 852 1633
Si2400
40 Rev. 1.3
7. Low Level DSP Control
Although not necessary for most applications, the DSP
low-level control functions are available for users with
very specific applications requiring direct DSP control.
7.1. DSP Registers
Several DSP registers are accessible through the
Si2400 microcontroller via S-registers SE5, SE6, SE7
and SE8. SE5 and SE6 are used as conduits to write
data to specific DSP registers and read status. SE8
defines the function of SE5 and SE6 depending on
whether they are being written to or read from. Care
must be exercised when writing to DSP registers. DSP
registers can only be written while the Si2400 is on-
hook and in the Command mo de . Writing to any r egi ster
address not listed in Tables 24 and 25 or writing out-of-
range values is likely to cause the DSP to exhibit
unpredictable behavior.
The DSP register address is 16-bits wide and the DSP
data field is 14-bits wide. DSP register addresses and
data are written in hexadecimal. To write a value to a
DSP register, the register address is written then the
data is written. When SE8 = 0x00, SE5(DADL) is written
with the low bits [7:0] of the DSP register address and
SE6 (DADH) is written with the high bits [15:8] of the
DSP address. When SE8 = 0x01, SE5 (DDL) is written
with the low bits [7:0] of the DSP data word
corresponding to the previously written address and
SE6 (DDH) is written with the high bits [15:8] of the data
word corresponding to the previously written address.
Example 1 below illustrates the proper procedure for
writing to DSP registers.
Example1: The user would like to program call
progress filter coefficient A2_k0 (0x15) to be 309
(0x135).
Host Command:
ATSE8=00SE6=00SE5=15SE8=01SE6=01SE5=35SE8=00
In the command above, ATSE8=00 sets up registers
SE5 and SE6 as DSP address registers. SE6=00 sets
the high bits of the address, and SE5=15 sets the low
bits. SE8=01 sets up registers SE5 and SE6 as DSP
data registers for the previously written DSP address
(0x15). SE6=01 sets the high 6 bits of the 14-bit data
word, and S E5=35 sets the low 8 bits of the 14-bit data
word.
Table 24. Low-Level DSP Parameters
DSP Reg. Addr. Name Description Function Default
(dec)
0x0002 XMTL DAA modem full scale transmit level,
default = –10 dBm Level = 20log10 (XTML/4096)
–10 dBm 4096
0x0003 DTML DTMF high tone transmit level,
default = –5.5 dBm Level = 20log10 (DTML/4868)
–5.5 dBm 4868
0x0004 DTMT DTMF twist ratio (low/high), defaul t = –2 dBm Level = 20log10 (DTMT/3277) –
2dB 3277
0x0005 UFRQ Use r-defined transmit tone frequency. See
register SE5 (SE8=0x02 (Write Only)) f = (9600/512) UFRQ (Hz) 91
0x0006 CPDL Call progress detect level (see Figure 13),
default = –43 dBm Level = 20log10 (4096/CPDL)
–43 dBm 4096
0x0007 UDFD1 User-defined freq ue n cy de te cto r 1. Center
frequency for detector 1. UDFD1 = 8192 cos (2π f/9600) 4987
0x0008 UDFD2 User-defined freq ue n cy de te cto r 2. Center
frequency for detector 2. UDFD2 = 8192 cos (2π f/9600) 536
0x0009 UDFD3 User-defined freq ue n cy de te cto r 3. Center
frequency for detector 3. UDFD3 = 8192 cos (2π f/9600) 4987
0x000A UDFD4 User-d ef i ne d fr eq ue n cy de te cto r 4. Cent er
frequency for detector 4. UDFD4 = 8192 cos (2π f/9600) 536
0x000B TGNL Tone generation level associated with TONC
(SE5 (SE8 = 0x02) Write Only Definition),
default = –10 dBm
Level = 20log10 (TGNL/2896)
– 10 dBm 2896
Si2400
Rev. 1.3 41
Table 25 defines the relationship between SE5, SE6, and SE8.
0x000E UDFSL Sensitivity setting for UDFD1–4 detectors,
default = –43 dBm Sensitivity = 10log10(UDFSL/
4096) – 43 dBm 4096
0x0024 CONL Carrier ON level. Carrier is valid once it
reaches this level. Level = 20log10(2620/CONL) –
43 dBm 2620
0x0025 COFL Carrier OFF level. Carrier is invalid once it
falls below this level. Level = 20log10(3300/COFL) –
45.5 dBm 3300
0x0026 AONL Answer ON level. Answer tone is valid once it
reaches this level. Level = 10log10(AONL/107) –
43 dBm 67
0x0027 AOFL Answer OFF level. Answer tone is invalid
once it fall below this level. Level = 10log10(AOFL/58) –
45.5 dBm 37
Table 25. SE5, SE6, and SE8 Relationship
SE8 SE6 SE5
R/W Name Description Name Description
0x00 W DADH DSP register address bits [15:8] DADL DSP register address bits [7:0]
0x01 W DDH DSP register data bits [15:8] DDL DSP register data bits [7:0]
0x02 R DSP1 7 = DSP data available.
6 = Tone detected.
5=Reserved.
4:0 = Tone type.
0x02 W DSP3 7 = Enable squaring function.
6 = Call progress cascade disable.
5=Reserved.
4 = User ton e 3 and 4 reporting .
3 = User ton e 1 and 2 reporting .
2 = V.23 tone reporting.
1 = Answer tone reporting.
0 = DTMF tone reporting.
DSP2 7 = Reserved.
6:3 = DTMF tone to transmit.
2:0 = Tone type.
Table 24. Low-Level DSP Parameters (Continued)
DSP Reg. Addr. Name Description Function Default
(dec)
Si2400
42 Rev. 1.3
7.2. Call Progress Filters
The programmable call progress filter coefficients are
located in DSP address locations 0x0010 through
0x0023. There are two independent 4th order filters A
and B, each consisting of two biquads, for a total of 20
coefficients. Coefficients are 14 bits (–8192 to 8191)
and are interpreted as, for example, b0 = value/4096,
thus giving a floating point value of approximately –2.0
to 2.0. Output of each biquad is calculated as
w[n] = k0 zx[n] + a1 zw[n – 1] + a2 zw[n – 2]
y[n] = w[n] + b1 zw[n – 1] + b2 zw[ n – 2] .
The output of the filters is input to an energy detector
and then compared to a fixed threshold with hysteresis
(DSP register CPDL). Defaults shown are a bandpass
filter from 290–630 Hz (–3 dB). These registers are
located in the DSP and thu s must be writte n in the same
manner described in “DSP Registers”.
The filters may be configured in either parallel or
cascade through SE6[6] (CPCD) with SE8 = 0x02, and
the output of filter B may be squared by selecting
SE6[7] (CPSQ) = 1b. Figure 13 shows a block diagram
of the call progress filter structure.
Figure 13. Programmable Call Progress Filter Architecture
Table 26. Call Progress Filters
DSP Register
Address Coefficient Default (dec)
0x0010 A1_k0 256
0x0011 A1_b1 –8184
0x0012 A1_b2 4096
0x0013 A1_a1 7737
0x0014 A1_a2 –3801
0x0015 A2_k0 1236
0x0016 A2_b1 133
0x0017 A2_b2 4096
0x0018 A2_a1 7109
0x0019 A2_a2 –3565
0x001A B1_k0 256
0x001B B1_b1 –8184
0x001C B1_b2 4096
0x001D B1_a1 7737
0x001E B1_a2 –3801
0x001F B2_k0 1236
0x0020 B2_b1 133
0x0021 B2_b2 4096
0x0022 B2_a1 7109
0x0023 B2_a2 –3565
Filter B Energy
Detect
1
1
0
1
0
Filter A
Filter Input
y = x2
CPSQ
Energy
Detect
0CPCD
Max
(A,B) Hysteresis A > B?
20log 10 (4096/CPDL) –34 dBm
TDET
A
B
A
B
CPCD 0
Si2400
Rev. 1.3 43
8. S Registers
Any register not documented here is reserved and should not be written. Bold selection in bit-mapped registers
indicate default values.
Table 27. S-Register Summary
“S”
Register Register
Address
(hex)
Name Function Reset
S00 0x00 NR Number of rings before answer; 0 suppresses auto answer. 0x00
S01 0x01 DW Number of seconds modem waits before dialing after going
off-hook (maximum of 109 se co nd s) . 0x03
S02 0x02 CW Number of seconds modem waits for a dial tone before hang-up
added to time specified by DW (maximum of 109 seconds). 0x14
S03 0x03 CLW Duration that the modem waits (53.33 ms units) after loss of car-
rier before hanging up. 0x0E
S04 0x04 TD Both duration and spacing (5/3 ms units) of DTMF dialed tones. 0x30
S05 0x05 OFFPD Duration of off-hook time (5/3 ms units) for pulse dialing. 0x18
S06 0x06 ONPD Duration of on-hook time (5/3 ms units) for pulse dialing. 0x24
S07 0x07 MF1 This is a bit mapped register.10x01
S08 0x08 MNRP Minimum ring period (5/3 ms units).20x0A
S09 0x09 MXRP Maximum ring period (5/3 ms units).20x28
S0A 0x0A ROT Ringer of f time (53.333 ms units).20x4B
S0B 0x0B MNRO Minimum ringer off time (10 ms units).20x08
S0C 0x0C MF2 This is a bit mapped register.10x00
S0D 0x0D RPE Ringer off time allowed erro r (53.333 ms units).20x16
S0E 0x0E DIT Pulse dialing Interdigit time (10 ms units added to a minimum
time of 64 ms). 0x46
S0F 0x0F TEC TIES escape character. Default = +. 0x2B
S10 0x10 TDT TIES delay time (256 z5/3 ms units). 0x07
S11 0x11 ONHI This is a bit mapped register.10x48
S12 0x12 OFHI This is a bit mapped register.10x40
S13 0x13 MF3 This is a bit mapped register.10x10
S14 0x14 MF4 This is a bit mapped register.10x00
S15 0x15 MLC This is a bit mapped register.10x84
S16 0x16 BTON Busy tone on. Time that the busy tone must be on (10 ms units)
for busy tone detector. 0x32
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
Si2400
44 Rev. 1.3
S17 0x17 BTOF Busy tone off. Time that the busy tone must be off (10 ms units)
for busy tone detector. 0x32
S18 0x18 BTOD Busy tone delta. Detector Time Delta (10 ms). A busy tone is
detected to be valid if (BTON – BTOD < on time < BTON +
BTOD) and (BTOF – BTOD < off time < BTOF + BTOD).
0x0F
S19 0x19 RT ON Ringback tone on. Time that the ringback tone must be on
(53.333 ms units) for ringback tone detector. 0x26
S1A 0x1A RTOF Ringback tone off. Time that the ringback tone must be off
(53.333 ms units) for ringback tone detector. 0x4B
S1B 0x1B RTOD Detector time delta (53.333 ms units). A ringback tone is deter-
mined to be valid if (RT ON – RTOD < on time < RTON + RTOD)
and (RTOF – RTOD < off time < RTOF + RTOD).
0x07
S1C 0x1C DTT Dial tone detect time. The time that the dial tone must be valid
before being detected
(10 ms units).
0x0A
S1D 0x1D DTMFD DTMF detect time. The time that a DTMF tone must be valid
before being detected (10 ms units). 0x03
S1E 0x1E TATL Transmit answer tone length. Answer tone length in seconds
when answering a call (1 second units). 0x03
S1F 0x1F ATTD Answer tone to transmit delay. Delay between answer tone end
and transmit data start (5/3 ms units). In the !7 mode, this is a bit-
mapped register.
0x2D
S20 0x20 UNL Unscrambled ones length. Minimum length of time required for
detection of unscrambled binary ones during V.22 handshaking
by a calling modem (5/3 ms units).
0x5D
S21 0x21 TSOD Transmit scrambled ones delay. Time between unscrambled
binary one detection and scrambled binary one transmission by
a call mode V.22 modem (53.3 ms units).
0x09
S22 0x22 TSOL Transmit scrambled ones length . Length of time scr ambled ones
are sent by a call mode V.22 modem (5/3 ms units). 0xA2
S23 0x23 VDDL V.22 data delay low. Delay between handshake complete and
data conne ction for a V.22 call mod e modem (5/3 ms units added
to the time specified by VDDH).
0xCB
S24 0x24 VDDH V.22 data delay high. Delay between handshake complete and
data connection for a V.22 call mode modem (256 z5/3 ms units
added to the time specified by VDDL).
0x08
S25 0x25 SPTL S1 pattern time length. Amount of time the unscrambled S1 pat-
tern is sent by a call mode V.22bis modem (5/3 ms units). 0x3C
Table 27. S-Register Summary (Continued)
“S”
Register Register
Address
(hex)
Name Function Reset
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
Si2400
Rev. 1.3 45
S26 0x26 VTSO V.22bis 1200 bps scrambled ones length. Minimum length of
time for transmission of 1200 bps scrambled binary ones by a
call mode V.22bis modem after the end of pattern S1 detection
(53.3 ms).
0x0C
S27 0x27 VTSOL V.22bis 240 0 bps scrambled ones leng th low. Minimum length of
time for transmission of 2400 bps scrambled binary ones by a
call mode V.22bis modem (5/3 ms units).
0x78
S28 0x28 VTSOH V.22bi s 2400 bps scrambled ones length high. Minimum length
of time for transmission of 2400 bps scrambled binary ones by a
call mode V.22bis modem (256 z5/3 ms units added to the time
specified by VTSOL).
0x08
S29 0x29 IS Intrusion suspen d. When S82[2:1] (IB) = 10b, this register sets
the length of time from when dialing begins that the off-hook
intrusion algorithm is blocked (suspended) (500 ms units).
0x00
S2A 0x2A RSO Receive scrambled ones V.22bis (2400 bps) length.
Minimum length of time required for detection of scrambled
binary ones during V.22bis handshaking by the answering
modem after S1 pattern conclusion (5/3 ms units).
0xD2
S2B 0x2B DTL V.23 direct turnaround car rier length. Minimum length of time th at
a master mode V.23 modem must detect carrier when searching
for a direct turnaround sequence (5/3 ms units). In the !7 alarm
mode, this register functions as pulse on time.
0x18
S2C 0x2C DTTO V.23 direct turnaround timeout. Length of time that the modem
searches for a direct turnaround carrier (5/3 ms units added to a
minimum time of 42 6.66 ms). In th e !7 ala rm mo d e, th is reg ist er
functions as pulse off time.
0x08
S2D 0x2D SDL V.23 slave carrier detect lo ss. Minimum length of time that a
slave mode V.23 modem must lose carrier before searching
for a reverse turnaround sequence (5/3 ms units). In the !7
alarm mode, this register functions as pulse interdigit time
(10 ms units).
0x0C
S2E 0x2E RTCT V.23 reverse turnaround carrier timeout. Amount of time a slave
mode V.23 modem will search for carriers during potential
reverse turnaround sequences (5/3 ms units). In the !7 alarm
mode, this register functions as Handshake End to TX Data
delay (10 ms units).
0x84
S2F 0x2F FCD F SK conn ection delay low. Amount of time delay added
between end of answer tone handshake and actual modem
connection for FSK modem connections (5/3 ms units).
0x3C
Table 27. S-Register Summary (Continued)
“S”
Register Register
Address
(hex)
Name Function Reset
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
Si2400
46 Rev. 1.3
S30 0x30 FCDH FSK connection delay high. Amount of time delay added
between end of answer tone han dshake and actual modem con-
nection for FSK modem connections (256 z5/3 ms units).
0x00
S31 0 x31 RATL Receive answe r to ne leng th . Minimum leng th of time required
for detection of a CCITT answer tone (5/3 ms units). 0x3C
S32 0x32 OCDT The time after going off hook when the loop current sense bits
are checked for overcurrent status (5/3 ms units). 0x0C
S33 0x33 MDMO This is a bit mapped register.10x80
S34 0x34 TASL Answer tone length when answering a call (5/3 ms units). This
register is only used if TATL (1E) has a value of zero. 0x5A
S35 0x35 RSOL Receive scrambled ones V.22 length (5/3 ms units). Minimum
length of time that an originating V.22 (1200 bps) modem must
detect 1200 bps scrambled ones during a V.22 handshake.
0xA2
S36 0x36 SKDTL Second kissoff tone detector length. The security modes A1 and
!1 will echo a “k” if a kissoff tone longer than the value stored in
SKDTL is detected (10 ms units.) In the !7 security mode, this
register represents a bit-mapped regi ster.
0x30
S37 0x37 CDR Carrier detect return. Minimum length of time that a carrier must
return and be detected in orde r to be recognized af ter a carrier
loss is detected
(5/3 ms units).
0x20
S38 0x38 ARM2 This is a bit-mapped register.10x38
S39 0x39 CDT Carrier detect timeout. Amount of time modem will wait for carrier
detect before aborting call (1 second units). In the !7 alarm
mode, this register functions as Han dshake Tone T imeout, which
defines how long the Si24 00 waits for a h andsh ake prior to send-
ing the “N” result code.
0x3C
S3A 0x3A ATD Delay between going of f-h ook and answer tone generation when
in answer mode (53.33 ms units). 0x29
S3B 0x3B RP Minimum number of consecutive ring pulses per ring burst. 0x03
S3C 0x3C CIDG This is a bit mapped register.10x04
S62 0x62 RC This is a bit mapped register.10x00
S82 0x82 IST This is a bit mapped register.10x00
S83 0x83 DCID DTMF caller ID initialization. —
SD1 0xD1 INTS Intrusion state. 0x00
SDB 0xDB LVCS Loo p voltage (on-hook)/loop current (off -hook) register 0x00
Table 27. S-Register Summary (Continued)
“S”
Register Register
Address
(hex)
Name Function Reset
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
Si2400
Rev. 1.3 47
SDF 0xDF DGSR This is a bit mapped register.10x00
SE0 0xE0 CF1 This is a bit mapped register.10x22
SE1 0xE1 CLK1 This is a bit mapped register.10x07
SE2 0xE2 GPIO This is a bit mapped reg i ster.10x00
SE3 0xE3 GPD This is a bit mapped register.10x00
SE4 0xE4 CF5 This is a bit mapped register.10x00
SE5 0xE5 D ADL (SE8 = 0x00) Write only definition. DSP regis ter addr ess lowe r
bits [7:0].10x00
SE5 0xE5 DDL (SE8 = 0x01) Write only definition. DSP data word lower bits
[7:0].10x00
SE5 0xE5 DSP1 (SE8 = 0x02) Read only definition. This is a bit mapped regi ster.10x00
SE5 0xE5 DSP2 (SE8 = 0x02) Write only definition. This is a bit mapped register.10x00
SE6 0xE6 DADH (SE8 = 0x00) Write only definition. DSP register address uppe r
bits [15:8] 0x00
SE6 0xE6 DDH (SE8 = 0x01) Write only definition. DSP data word upper bits
[13:8] 0x00
SE6 0xE6 DSP3 (SE8 = 0x02) Write only definition. This is a bit mapped register.10x00
SE8 0xE8 DSPR4 Set the mode to define E5 and E6 for low level DSP control. 0x00
SEB 0xEB TPD This is a bit mapped register.10x00
SF0 0xF0 DAA0 This is a bit mapped register.10x00
SF1 0xF1 DAA1 This is a bit mapped register.10x1C
SF2 0xF2 DAA2 This is a bit mapped register.10x00
SF4 0xF4 DAA4 This is a bit mapped register.10x0F
SF5 0xF5 DAA5 This is a bit mapped register.10x08
SF6 0xF6 DAA6 This is a bit mapped register.10x00
SF7 0xF7 DAA7 This is a bit mapped register.10x10
SF8 0xF8 DAA8 This is a bit mapped register.1—
SF9 0xF9 DAA9 This is a bit mapped register.10x20
Table 27. S-Register Summary (Continued)
“S”
Register Register
Address
(hex)
Name Function Reset
Notes:
1. These registers are explained in detail in the following section.
2. The ring detector will only detect ringing if the ring burst on/off times meet the settings in MNRP, MXRP, MNRU, ROT,
and REP.
Si2400
48 Rev. 1.3
Table 28. Bit Mapped Register Summary
“S”
Register Register
Address
(hex)
Register
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default
Binary
S07 0x07 MF1 HDEN BD V23R V23T BAUD CCITT FSK 0000_0001
S0C 0x0C MF2 CDE CIDM[1:0] 9BF BDL MLB MCH 0000_0000
S11 0x11 ONHI DVL[2:0] AVL[4:0] 0100_1000
S12 0x12 OFHI DCL[2:0] ACL[4:0] 0100_0000
S13 0x13 MF3 JID BTID OFHE OFHD ONHD CIDB CIDU PCM 0001_0000
S14 0x14 MF4 MRCD UDF TEO AOC OD NLD IND RD 0000_0000
S15 0x15 MLC ATPRE VCTE FHGE ENGE STB BDA[2:1] NBE 1000_0100
S1F 0x1F ARM3 KOT[2:0] IMT[4:0] 0010_1101
S33 0x33 MDMO DON DOF NAT TSAC 1000_0000
S36 0x36 ARM1 POF[1:0] PON[1:0] IDKT[1:0] IT[1:0] 0011_0000
S38 0x38 ARM2 DBD DCF[1:0] HMT[2:0] HF[1:0] 0011_1000
S3C 0x3C CIDG CIDG[2:0] 0000_0100
S62 0x62 RC CLD OCR LLC WOR FLS IR NLR RR 0000_0000
S82 0x82 IST IST[3:0] LCLD IB[1:0] 0000_0000
SDF 0xDF DGSR DGSR[6:0] 0000_0000
SE0 0xE0 CF1 ICTS ND SD[2:0] 0010_0010
SE1 0xE1 CLK1 MCKR[1:0] CLKD[4:0] 0000_0111
SE2 0xE2 GPIO GPIO4[1:0] GPIO3[1:0] GPIO2[1:0] GPIO1[1:0] 0000_0000
SE3 0xE3 GPD AING[1:0] GPD4 GPD3 GPD2 GPD1 0000_0000
SE4 0xE4 CF5 NBCK SBCK DRT[1:0] GPE APO TRSP 0000_0000
SE5 0xE5 DADL 0000_0000
SE5 0xE5 DDL 0000_0000
SE5 0xE5 DSP1 DDAV TDET TONE[4:0] 0000_0000
SE5 0xE5 DSP2 DTM[3:0] TONC[2:0] 0000_0000
SE6 0xE6 DADH 0000_0000
SE6 0xE6 DDH 0000_0000
SE6 0xE6 DSP3 CPSQ CPCD USEN2 USEN1 V23E ANSE DTMFE 0000_0000
Si2400
Rev. 1.3 49
SEB 0xEB TPD PDDE 0000_0000
SF0 0xF0 DAA0 LM OFHK 0000_0000
SF1 0xF1 DAA1 BTE PDN PDL HBE 0001_1100
SF2 0xF2 DAA2 FDT 0000_0000
SF4 0xF4 DAA4 SQLH ARG[2:0] ARL[1:0] ATL[1:0] 0000_1111
SF5 0xF5 DAA5 FULL DCTO OHS ACT DCT[1:0] RZ RT 0000_1000
SF6 0xF6 DAA6 FJM DIAL VOL FLVM 0000_0000
SF7 0xF7 DAA7 LMO LIM 0001_0000
SF8 0xF8 DAA8 LRV[3:0] —
SF9 0xF9 DAA9 OVL BTD ROV 0010_0000
Table 28. Bit Mapped Register Summary (Continued)
“S”
Register Register
Address
(hex)
Register
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default
Binary
Si2400
50 Rev. 1.3
Reset settings = 0000_0001b (0x01)
S07 (MF1). Modem Functions 1
Bit D7 D6 D5 D4 D3 D2 D1 D0
Name HDEN BD V23R V23T BAUD CCITT FSK
Type R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7 HDEN HDLC Framing.
0 = Disable.
1 = Enable.
6BD
Blind Dialing.
0=Disable.
1 = Enable (Blind dialing occurs immediately after “ATDT#” command).
5V23R
V.23 Receive.*
V.23 75 bps send/600 (BAUD = 0) or 1200 (BAUD = 1) bps receive.
0=Disable.
1 = Enable.
4V23T
V.23 Transmit.*
V.23 600 (BAUD = 0) or 1200 (BAUD = 1) bps send/75 bps receive.
0=Disable.
1 = Enable.
3 Reserved Read returns zero.
2BAUD
2400/1200 Baud Select.*
2400/1200 baud select (V23R = 0 and V23T = 0).
0=1200
1 = 2400
600/1200 baud select ( V2 3R = 1 and V23T = 1).
0=600
1 = 1200
1 CCITT CCITT/Bell Mode.*
0=Bell.
1=CCITT.
0FSK
300 bps FSK.*
0=Disable.
1=Enable.
*Note: See Table 12 on page 15 for proper setting of modem proto cols.
Si2400
Rev. 1.3 51
Reset settings = 0000_0000b (0x00)
S0C (MF2). Modem Functions 2
BitD7D6D5D4D3D2D1D0
Name CDE CIDM 9BF BDL MLB MCH
Type R/W R/W R/W R/W R/W R/W
Bit Name Function
7CDE Carrier Detect Enable.
0=Disable.
1 = Enable GPI02 as an active low carrier detect pin (must also set SE2[3:2]
[GPIO2] = 01b).
6:5 CIDM Caller ID Monitor.
00 = Caller ID monitor disabled (Normal caller ID opera tion).
01 = Caller ID monitor enabled. Si24 00 must detect channel seizure signal followed by
marks in order to report caller ID data.
10 = Caller ID monitor enabled. Si2400 must detect a DTMF A or D followed by marks in
order to report caller ID data.
11 = Caller ID monitor enabled. Si2400 must only de tect marks in order to report caller ID
data.
4 Reserved Read returns zero.
39BF
Ninth Bit Function.
Only valid if the ninth bit escape is set S15[0] (NBE).
0 = Ninth bit equivalent to ALERT.
1 = Ninth bit equivalent to HDLC EOFR.
2BDL
Blind Dialing.
0 = Blind dialing disabled.
1 = Enables blind dialing after dial timeout register S02 (CW) expires.
1MLB
Modem Loopback.
0 = Not swapped.
1 = Swaps frequency bands in modem algorithm to do a loopback in a test mode.
0MCH
Miscellaneous Characters.
0 = Disables “.” and “/” character echoing.
1 = Enables “.” and “/” character echoing to indicate tone on and to ne of f fo r !7 operatio n.
Si2400
52 Rev. 1.3
Reset settings = 0100_1000b (0x48)
Reset settings = 0100_0000b (0x40)
S11 (ONHI). On-Hook Intrusion
BitD7D6D5 D4 D3D2 D1 D0
Name DVL AVL
Type R/W R/W
Bit Name Function
7:5 DVL Differential Voltage Level.
Differential vo ltage level to detect intrusion event (2.75 V units.)
4:0 AVL Absolute Voltage Level.
Absolute voltage level to detect intrusion event (2.75 V units added to 3 V.)
S12 (OFHI). Off-Hook Intrusion
BitD7D6D5 D4 D3D2 D1 D0
Name DCL ACL
Type R/W R/W
Bit Name Function
7:5 DCL Differential Current Level.
Differential cu rrent level to detect intrusion event (3 mA units.)
4:0 ACL Absolute Current Level.
When S13[4] (OFHD) = 0b, ACL represents the absolute current threshold used by the
off-hook intrusion algorithm (3 mA units added to 12 mA.)
When OFHD = 1b, see "5.5.5.Differential Algorithm #2" on page 20.
Si2400
Rev. 1.3 53
Reset settings = 0001_0000b (0x10)
S13 (MF3). Modem Functions 3
BitD7D6D5D4D3D2D1D0
Name JID BTID OFHE OFHD ONHD CIDB CIDU PCM
Type R/W R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7JIDJapan Caller ID.
0 = Disable.
1 = Enable.
6BTID
BT Caller ID Wetting Pulse.
0=Enable.
1=Disable.
5OFHE
Enable Off-Hook.
Enable off hook in current limit mode for overcurrent detection.
0 = Disable.
1 = Enable.
4OFHD
Off-Hook Intrusion Detect Method.
0=Absolute.
1 = Differential.
3ONHDOn-Hook Intrusion Detect Method.
0=Absolute.
1 = Differential.
2CIDB
British Telecom Caller ID Decode.
0 = Disable.
1 = Enable.
1CIDU
BellCore Caller ID Decode.
0 = Disable.
1 = Enable.
0PCM
PCM Data Mode.
DTE rate must be ≥ 228613, and flow control must be used.
0 = Disable.
1 = Enable.
Si2400
54 Rev. 1.3
Reset settings = 0000_0000b (0x00)
S14 (MF4). Modem Functions 4
BitD7D6D5D4D3D2D1D0
Name MRCD UDF TEO AOC OD NLD IND RD
Type R/W R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7 MRCD Disable Modem Result Codes. (See S62 also.)
0 = Enables the following modem result codes:
1 = Disables the following modem result codes:
Intrusion—” i” an d “ I”
Line present—”l” and “L”
Flash—”f”
Ring—”R”
Register S62 can be used to individually re-enable particular result codes.
6 UDF User Defined Frequency.
0 = Disable.
1 = Enable user defined frequency detectors in A0 and !0 mode s.
5TEO
TIES Escape Operation.
0 = Disable TIES escape operation.
1 = Enable TIES.
4AOC
AutoOverCurrent Detection.
0 = Disables AutoOverCurrent detection.
1 = Enables AutoOverCurrent detection.
3OD
Overcurrent Detected (Sticky).
2NLDNo Phone Line.
This bit is sticky while off-hook if S82 [3 ] (LCLD) = 1b, and non-sticky (status) while on -
hook. NLD remains sticky for 800 ms after going from off-hook to on-hook.
1IND
Intrusion Detected.
This bit is normally NOT sticky so that the user may monitor/poll for intrusion manually.
However, during dialing and during data mode, it is impossible to monitor/poll this bit.
Therefore, if the Si2400 is eithe r di aling or in da ta mode, this bit is sticky. If triggered dur-
ing data mode, this bit will remain sticky for 800 ms after the Si2400 goes back on-hook.
0RD
Ring Detected (Sticky).
This bit is normally sticky, but is cleared when the Si2400 goes from on -h ook to off-hook.
Si2400
Rev. 1.3 55
Reset settings = 1000_0100b (0x84)
S15 (MLC). Modem Link Control
BitD7D6D5D4D3D2D1D0
Name ATPRE VCTE FHGE ENGE STB BDA NBE
Type R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7ATPREAnswer Tone Phase Reversal.
0=Disable.
1 = Enable answer tone phase reversal.
6VCTEV.25 Calling Tone.
0 = Disable.
1 = Enable V.25 calling tone.
5FHGE
550 Hz Guardtone.
0 = Disable.
1 = Enable 550 Hz guardtone.
4ENGE
1800 Hz Guardtone.
0 = Disable.
1 = Enable 1800 Hz guard tone.
3STB
Stop Bits.
0 = 1 stop bit.
1 = 2 stop bits.
2:1 BDA Bit Data.
00 = 6 bit data.
01 = 7 bit data.
10 = 8 bit data.
11 = 9 bit data.
0NBE
Ninth Bit Enable.
0 = Disable.
1 = Enable ninth bit as Escape and nin th bit function (register C).
Si2400
56 Rev. 1.3
Reset settings = 0010_1101b (0x2D)
S1F (ARM3). Alarm 3 (!7 Mode Only)
BitD7D6D5D4D3D2D1D0
Name KOT IMT
Type R/W R/W
Bit Name Function
7:5 KOT Kissoff Timeout.
1 s units. Maximum 7 s.
4:0 IMT Intermessage Timing.
500 ms units. Maximum 8 s.
Note: S1F is reconfigured as Alarm 3, a bit-mapped register, in !7 mode only. In all other modes, S1F is ATTD (Answer Tone
to Transmit Delay).
Si2400
Rev. 1.3 57
Reset settings = 1000_0000b (0x80)
S33 (MDMO). Modem Override
BitD7D6D5D4D3D2D1D0
Name DON DOF NAT TSAC
Type R/W R/W R/W R/W
Bit Name Function
7 Reserved Read returns one.
6DON
On-Hook Intrusion Detect.
0=Enable.
1=Disable*.
5DOF
Off-Hook Intrusion Detect.
0=Enable.
1=Disable.
4:2 Reserved Read returns zero.
1NAT
No Answer Tone.
0 = Disable.
1 = Enable no answer tone fast handshake.
0TSAC
Transmit Scrambler Active.
0 = Disable.
1 = Force transmit scrambler activ e once connected.
*Note: When the Si2400 is on hook, the on-hook intrusion detector might not be immediately disabled by only setting the
S33[6] (DON) = 1b (S33 = 0xCX, X indicates an otherwise appropriate value.) In order to guarantee that the result
codes and the updating of S14[2] (NLD) and S14[1] (IND) are immediately disabled, ATS33=CX must be followed by
ATSD1=00S14=X0.
Si2400
58 Rev. 1.3
Reset settings = 0011_0000b (0x30)
S36 (ARM1). Alarm 1 (!7 Mode Only)
BitD7D6D5D4D3D2D1D0
Name POF PON IDKT IT
Type R/W R/W R/W R/W
Bit Name Function
7:6 POF Pulse Off Time.
00 = 25 ms.
01 = 50 ms.
10 = 65 ms.
11 = Use S2C register.
5:4 PON Pulse On Time.
00 = 25 ms.
01 = 50 ms.
10 = 65 ms.
11 = Use S2B regist er.
3:2 IDKT Intermessage Delay and Kissoff Timeout.
This register field defines two p arameters. The Intermessa ge Delay defines the time the Si2400
waits prior to sen ding a subs equent messa ge. The Kissoff Timeo ut defines the time the Si2400
waits for a Kissoff Tone prior to declaring that there is no kissoff tone detected.
00 = Intermessage Delay is measure d relative t o the end of Kiss off and it is a fixed delay
of 2.4 s. The Kissoff Timeout is measured relative to the end of Kissoff and it is a fixed
value of 2 s.
01 = Intermessage Delay is measured relative to the end of Kissoff and it is determined by
S1F[4:0] (IMT). The Kissoff Timeout is measured relative to the end of Kissoff and it is deter-
mined by S1F[7:5] (KOT).
10 = Intermessage Delay is measured relative to the end of the previous me ssa g e and it is a
fixed delay of 3.4 s. The Kissoff Timeout is measured relative to the end of Kissoff and it is a
fixed value of 2 s.
11 = Intermessage Delay is measured relative to the end of the previous message and it is
determined by S1F[7:5] (KOT). The Kissoff Timeout is measured relative to the end of Kissoff
and it is determined by S1F[7:5] (KOT).
1:0 IT Interdigit Timing.
The controlled timing between the pu lse digits.
00 = The timing between the end of a digit to the start of the next digit is fixed at 660 ms.
01 = The timing between the end of a digit to the start of the next digit is defined by the S2D
register.
10 = The timing between the start of a digit to the start of the next digit is fixed at 800 ms.
11 = The timin g be twe e n the start of a digit to th e start of the next dig i t is def ine d by the S2D
register.
Note: S36 is reconfigured as Alarm 1, a bit-mapped register, in !7 mode only. In all other modes, S36 is SKDTL (Second
Kissoff Tone Detect Length).
Si2400
Rev. 1.3 59
Reset settings = 0011_1000b (0x38)
S38 (ARM2). Alarm 2 (!7 Mode Only)
BitD7D6D5D4D3D2D1D0
Name DBD DCF HMT HF
Type R/W R/W R/W R/W
Bit Name Function
7DBDDelay Before Data.
Time the Si2400 waits prior to transmitting data, relative to the end of the handshake
tone.
0 = 300 ms.
1 = Use S2E (RTCT) register contents.
6:5 DCF Data Carrier Frequency.
Frequency that the Si2400 will use to transmit.
00 = User program med. This is accomplished by accessin g DSP register 5 prior to using
the !7 command.
01 = 1800 Hz.
10 = 1900 Hz.
11 = 1850 Hz.
4:2 HMT Handshake Minimum Time.
The minimum required tone length for a handshake tone or a kissoff tone.
000 = 53 ms.
001 = 160 ms.
010 = 320 ms.
011 = 480 ms.
100 = 640 ms.
101 = 800 ms.
110 = 960 ms.
111 = 1120 ms.
1:0 HF Handshake Frequency.
The frequency that the Si2400 detects as Handshake and Kissoff Tone.
00 = User-defined frequency detectors must be programmed prior to using the !7
command. See DSP Registers.
01 = 140 0 Hz only.
10 = 230 0 Hz only.
11 = 1400 Hz or 2300 Hz.
Note: S38 (ALARM2) is used in !7 mode only.
Si2400
60 Rev. 1.3
Reset settings = 0000_0100b (0x04)
S3C (CIDG). Caller ID Gain
BitD7D6D5D4D3D2D1D0
Name CIDG
Type R/W
Bit Name Function
7:3 Reserved Read returns 0.
2:0 CIDG Caller ID Gain.
The Si2400 dynamically sets the On-Hook Analog Receive Gain SF4[6:4] (ARG) to
CIDG during a caller ID event (o r continuously if S0C[6:5] (CIDM = 11b). This field should
be set prior to caller ID operation.
000=7dB
001=6dB
010 = 4.8 dB
011=3.5dB
100 =2.0 dB
101=0dB
110=–2.0dB
111 = –6.0 dB
Si2400
Rev. 1.3 61
Reset settings = 0000_0000b (0x00)
S62 (RC). Result Codes Override
BitD7D6D5D4D3D2D1D0
Name CLD OCR LLC WOR FLS IR NLR RR
Type R/W R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7CLDCarrier Loss Detector.
0 = Default.
1 = Caller ID sensit ivity ca n be increa se d by 5 dB . Whe n CLD = 1, the host is respo nsi-
ble for terminating caller ID reception by asserting an escape and issuing the ATH com-
mand.
Note: This bit also controls the carrier loss detection of non-caller ID modes of operation.
Therefore, the host must set CLD = 0 prior to answering a call via “ATA” or initiating a call
via “ATDT” or “ATDP”.
6OCROvercurrent Result Code (“x”).
0=Enable.
1=Disable.
5LLC
Low Loop Current (required for CTR21 operation).
This feature only wor ks wh en SD F ≠ 0x00.
0 = Disable.
1 = Enable.
4WOR
Wake-On-Ring Alert.
0 = Alert is not asserted upon a wake-on-ring event.
1 = Alert is asse rte d upon a wa ke- o n- rin g ev en t SE 2[ 7:6 ] (G PIO 4) = 11b.
3FLS
Hookswitch Flash Result Code (“f”).*
0 = Disable.
1 = Enable.
2IR
Intrusion Result Code (“I” and “i”).*
0 = Disable.
1 = Enable.
1NLR
No Phone Line Result Code (“L” and “l”).*
0 = Disable.
1 = Enable.
0RR
Ring Result Code (“R”).*
0 = Disable.
1 = Enable.
*Note: S62[3] (FLS), S62[2] (IR), S62[1] (NLR), and S62[0] (RR) only apply if S14[7] (MRCD) = 1.
Si2400
62 Rev. 1.3
Reset settings = 0000_0000b (0x00)
Reset settings = 0000_0000b (0x00)
S82 (IST). Intrusion
BitD7D6D5D4D3D2D1D0
Name IST LCLD IB
Type R/W R/W R/W
Bit Name Function
7:4 IST Intru sio n Se ttl in g Time.
0000 = IST equals 1 second.
Delay between when the ISOmodem goes off-hook and the off-hook intrusion algorithm
begins (250 ms units).
3LCLD
Loop Current Loss Detect.
0 = Disable.
1 = Enables the reporting of “I” and “L” result codes while off-hook. Will assert ALERT if
GPIO4 (SE2[7:6]) is enabled as ALERT. Will assert NLD (S14[2]).
2:1 IB Intrusion Blocking.
This feature only works when SDF ≠ 0x00. Defines the method used to block the off-hook
intrusion algorithm from operating after dialing has begun.
00 = No intrusion blocking.
01 = Intrusion disabled from start of dial to end of dial.
10 = Intrusion disabled from start of dial to register S29 time out.
11 = Intrusion disabled from start of dial to carrier detect or to “N” or “n” result code.
0 Reserved Read returns 0.
SDF (DGSR). Intrusion Deglitch
BitD7D6D5D4D3D2D1D0
Name DGSR
Type R/W
Bit Name Function
7 Reserved Read returns zero.
6:0 DGSR Deglitch Sample Rate.
Sets the sample rate for the deglitch algorithm and the off-hoo k intr usion algorithm
(40 ms units).
0000000 = Disables the deg litch algor it hm, and s ets th e of f-hook in tru sion sample
rate to 200 ms and delay between compared samples to 800 ms.
Si2400
Rev. 1.3 63
Reset settings = 0010_0010b (0x22)
SE0 (CF1). Chip Functions 1
BitD7D6D5D4D3D2D1D0
Name ICTS ND SD
Type R/W R/W R/W
Bit Name Function
7:6 Reserved Read returns zero.
5ICTS
Invert CTS pin.
0 = Inverted (CTS).
1 = Normal (CTS).
4 Reserved Read returns zero.
3ND
0 = 8N1.
1 = 9N1 (hardware UART only).
2:0 SD Serial Dividers.
000 = 300 bps serial link.
001 = 1200 bps serial link.
010 = 2400 bps serial link.
011 = 9600 bps serial link.
100 = 19 20 0 bps serial link.
101 = 228613 bps serial link (0.8% er ror to 230400 bps ).
110 = 245760 bps serial link.
111 = 307200 bps serial link.
Si2400
64 Rev. 1.3
Reset settings = 0000_0111b (0x07)
SE1 (CLK1). Clock 1
BitD7D6D5D4D3D2D1D0
Name MCKR CLKD
Type R/W R/W
Bit Name Function
7:6 MCKR Microcontroller Clock Rate.
0 = Fastest 9.8304 MHz.
1 = 4.9152 MHz.
2 = 2.4576 MHz.
3=Reserved.
Note: MCKR must be set to 0 when the UART DTE rate is set to 228613 or greater
(SE0[2:0] (SD) = 101b, 110b or 111b).
5 Reserved Read returns zero.
4:0 CLKD CLK_OUT Divider.
00000 = Disable CLK_OUT pin.
CLK_OUT = 78.6432/(CLKD + 1) MHz.
00111b CLK_OUT = 9.8304 MHz.
Si2400
Rev. 1.3 65
Reset settings = 0000_0000b (0x00)
SE2 (GPIO). General Purpose Input/Output
BitD7D6D5D4D3D2D1D0
Name GPIO4 GPIO3 GPIO2 GPIO1
Type R/W R/W R/W R/W
Bit Name Function
7:6 GPIO4 GPIO4.
00 = Digital input.
01 = Digital output (relay drive).
10 = Analog input.
11 = ALERT function triggered by loss of carrier (always), V.23 reversal (always), wake-
on-ring S62[4] (WOR), parallel phone intru sio n S33[5] (DOF), or loss of loop current
S82[3] (LCLD).
5:4 GPIO3 GPIO3.
00 = Digital input.
01 = Digital output (relay drive).
01 = Analog input.
11 = ESCAPE function (digital input).
3:2 GPIO2 GPIO2*.
00 = Digital input.
01 = Digital output (relay drive; also used for CD function).
10 = Analog input.
11 = Reserved.
1:0 GPIO1 GPIO1*.
00 = Digital input.
01 = Digital output (relay drive).
10 = Analog input.
11 = Reserved.
*Note: To be used as analog input or GPIO pins; SE4[3] (GPE) and SE4[0] (TRSP) must both equal zero.
Si2400
66 Rev. 1.3
Reset settings = 0000_0000b (0x00)
SE3 (GPD). GPIO Data
BitD7D6D5D4D3D2D1D0
Name AING GPD4 GPD3 GPD2 GPD1
Type R/W R/W R/W R/W R/W
Bit Name Function
7:6 AING AIN Gain Bits.
00 = 0 dB
01 = 6 dB
10 = 2.5 dB
11 = 12 dB
5:4 Reserved Read returns zero.
3GPD4
GPIO4 Data.
0
1
2GPD3
GPIO3 Data.
0
1
1GPD2
GPIO2 Data.
0
1
0GPD1
GPIO1 Data.
0
1
Si2400
Rev. 1.3 67
Reset settings = 0000_0000b (0x00)
SE4 (CF5). Chip Functions 5
BitD7D6D5D4D3D2D1D0
Name NBCK SBCK DRT GPE APO TRSP
Type R R R/W R/W R/W R/W
Bit Name Function
7NBCK9600 Baud Clock (Read Only).
6 SBCK 600 Baud Clock (Read Only).
5:4 DRT Data Routing (See Figure 10).
00 = Data mode, DSP output transmitted to line, line received by DSP input.
01 = Voice mode , selected AIN transmitted to line, line received by AOUT.
10 = Loopback mode, RXD through microcontroller (DSP) to TXD. AIN looped to AOUT.
11 = Co de c mo de , da ta from D SPOUT to AOUT, AIN to DSPIN.
3 GPE* GPIO1 Enable.
0 = Disable.
1 = Enable GPIO1 to be HDLC end-of-frame flag.
2 Reserved Read returns zero.
1 APO Analog Power On.
0 = Disable.
1 = Power on analog ADC and DAC.
0TRSP*
TXD2/RXD2 Serial Port.
0 = Disable.
1 = Enable TXD2/RXD2 serial port so that RXD2 is GPIO1 and TXD2 is GPIO2.
*Note: GPE and TRSP are mutually exclusive. Only one can be set at any one time, and they override the settings in registers
GPIO2 and GPIO1. Once TXD2 and RXD2 are enabled through TRSP =1b, the primary serial port TXD and RXD no
longer function and pins TXD2 and RXD2 control the Si2400. This feature allows a second microcontroller to control
the Si2400.
Si2400
68 Rev. 1.3
Reset settings = 0000_0000b (0x00)
SE5 (DSP1). (SE8 = 0x02) Read Only Definition
BitD7D6D5D4D3D2D1D0
Name DDAV TDET TONE
Type RR R
Bit Name Function
7 DDAV DSP Data Available.
6TDETTon e Dete ct ed .
Indicates a TONE (any of type 0–25 below) has been detected.
0 = Not detected.
1=Detected.
5 Reserved Read returns zero.
4:0 TONE Tone Type Detected.
When TDET goes high, TONE indicates which tone has been detected from the following:
TONE Tone Type Priority
00000–01111 DTMF 0–15 (DTMFE = 1)1 See Table 23 on page 39 1
10000 Answer tone detected 2100 Hz (ANSE = 1)22
10001 Bell 103 answer tone detected 2225 Hz (ANSE = 1) 2
10010 V.23 forward channel mark 1300 Hz (V23E = 1)33
10011 V.23 backward ch an ne l mark 39 0 Hz (V23E = 1) 3
10100 User defined frequency 1 (USEN1 = 1)44
10101 User defined frequency 2 (USEN1 = 1) 4
10110 Call progress filter A detected 6
10111 User defined frequency 3 (USEN2 = 1)55
11000 User defined frequency 4 (USEN2 = 1) 5
11001 Call progress filter B detected 6
Notes:
1. SE6[0] (DTMFE) SE8 =0x02.
2. SE6[1] (ANSE) SE8 =0x02.
3. SE6[2] (V23E) SE8 =0x02.
4. SE6[3] (USEN1) SE8 =0x02.
5. SE6[4] (USEN2) SE8 =0x02.
Si2400
Rev. 1.3 69
Reset settings = 0000_0000b (0x00)
SE5 (DSP2). (SE8 = 0x02) Write Only Definition
BitD7D6D5D4D3D2D1D0
Name DTM TONC
Type WW
Bit Name Function
7 Reserved Always write zero.
6:3 DTM DTMF tone (0–15) to transmit when selected by TONC = 0 01b. See Table 23 on p age 39.
2:0 TONC Tone Tone Type
000 Mute
001 DTMF
010 2225 Hz Bell mod e an swe r to ne with ph a se re ve rs al
011 2100 Hz CCITT mode answer tone with phase reversal
100 2225 Hz Bell mode answer tone without phase reversal
101 2100 Hz CCITT mode answer tone without phase reversal
110 User-defined prog r am m abl e freq u en cy to ne (UF RQ)
(see Table 24 on page 40, default = 1700 Hz)
111 1300 Hz V.25 calling tone
Si2400
70 Rev. 1.3
Reset settings = 0000_0000b (0x00)
Reset settings = 0000_0000b (0x00)
SE6 (DSP3). (SE8 = 0x02) Write Only Definition
BitD7D6D5D4D3D2D1D0
Name CPSQ CPCD USEN2 USEN1 V23E ANSE DTMFE
Type WW WWWWW
Bit Name Function
7 CPSQ 0 = Disable.
1 = Enables a squaring function on the output of filter B before the input to A (cascade
only).
6CPCD
0 = Call progress filter B output is input into call progress filter A. Output from fil-
ter A is used in the detector.
1 = Cascade disabled. Two independent fourth order filters available (A and B). The
largest output of the two is used in the detecto r.
5 Reserved
4USEN2
0 = Disable.
1 = Enable the reporting of user defined frequency tones 3 and 4 through TONE.
3USEN1
0 = Disable.
1 = Enable the reporting of user defined frequency tones 1 and 2.
2V23E
0 = Disable.
1 = Enable the reporting of V.23 tones, 390 Hz and 1300 Hz.
1ANSE
0 = Disable.
1 = Enable the reporting of answer tones.
0 DTMFE 0 = Disable.
1 = Enable the reporting of DTMF tones.
SEB (TPD). Timer and Power Down
BitD7D6D5D4D3D2D1D0
Name PDDE
Type R/W
Bit Name Function
7:4 Reserved Read returns zero.
3 PDDE Power Down DSP Engine.
0=Power on
1 = Power down
2:0 Reserved Read returns zero.
Si2400
Rev. 1.3 71
Reset settings = 0000_0000b (0x00)
SF0 (DAA0). DAA Low Level Functions 0
BitD7D6D5D4D3D2D1D0
Name LM OFHK
Type R/W R/W
Bit Name Function
7:2 Reserved Read returns zero.
1LM
Hook Control/Status.1,2
OFHK LM LM0 Line Status Mode
0 0 1 On-hook
0 1 1 On-hook line monitor mode (Si3015 compatible)
100 Off-hook
Else Reserved
0OFHK
Notes:
1. See Register F7 on page 76 for LM0.
2. Under normal operation, the Si2400 internal microcontroller will automatically set these bits appropriately.
Si2400
72 Rev. 1.3
Reset settings = 0001_1100b (0x1C)
Reset settings = 0000_0000b (0x00)
SF1 (DAA1). DAA Low Level Functions 1
BitD7D6D5D4D3D2D1D0
Name BTE PDN PDL HBE
Type R/W R/W R/W
Bit Name Function
7BTEBilling Tone Enable.
When the Si3015 detects a billing tone, SF9[3] (BTD) is set.
0 = Disable.
1 = Enable.
6PDN
Power Down.
0 = Normal operation.
1 = Powers down the Si2400.
5PDL
Power Down Line-Side Chip (typically only used for board level debug.)
0 = Normal operation. Program the clock generator before clearing this bit.
1 = Places the Si3015 in lower power mode.
4:3 Reserved Do Not Modify
2HBE
Hybrid Transmit Path Connect.
0=Disable.
1=Enable.
1:0 Reserved Do Not Modify
SF2 (DAA2). DAA Low Level Functions 2
BitD7D6D5D4D3D2D1D0
Name FDT
Type R
Bit Name Function
7:4 Reserved Read only.
3FDT
Frame Detect (Typically only used for board-level debug.)
1 = Indicates link frame lock has been established.
0 = Indicates link frame lock has not been established.
2:0 Reserved Reserved
Si2400
Rev. 1.3 73
Reset settings = 0000_1111b (0x0F)
SF4 (DAA4). DAA Low Level Functions 4
BitD7D6D5D4D3D2D1D0
Name SQLH ARG ARL ATL
Type R/W R/W R/W R/W
Bit Name Function
7SQLHRing Squelch.
If the host implements a manual ring detect (bypassing the Si2400 micro), this bit must
be set, then cleared followin g a polarity reversal detection. Used to quickly recover of fset
on RNG1/2 pins after polarity reversal.
0 = Normal.
1 = Squelch.
6:4 ARG Analog Receive Gain.
Off-Hook On-Hook
000 = 0 dB gain 000 = 7 dB
001 = 3 dB ga in 001 = 6 dB
010 = 6 dB ga in 010 = 4.8 dB
011 = 9 dB gain 011 = 3.5 dB
1xx = 12 dB ga in 1xx = 2 .0 dB
3:2 ARL AOUT Receive—Path Level.
DAA receive path signal AOUT gain.
00 = 0 dB
01 = –6 dB
10 = –12 dB*
11 = Mute
1:0 ATL AOUT Transmit—Path Level.
DAA transmit path signal AOUT gain.
00 = –18 dB
01 = –24 dB
10 = –30 dB*
11 = Mute
Si2400
74 Rev. 1.3
Reset settings = 0000_1000b (0x08)
SF5 (DAA5). DAA Low Level Functions 5
BitD7D6D5D4D3D2D1D0
Name FULL DCTO OHS ACT DCT RZ RT
Type R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
7FULLFull Scale.
0 = Si3015 ADC/DAC full scale > –1 dBm.
1 = Si3015 ADC/DAC full scale > 3.2 dBm.
This bit changes the full scale of the ADC and DAC from –1 dBm min. to 3.2 dBm min. In
order to use this bit, the R2 resistor must be changed from 402 Ω to 243 Ω and ACT
(SF5, bit 4) must be set to 0. This bit is intended for use only in voice communications
and may be used in PCM modes.
6DCTO
DC Termination Off.
0 = Normal operation. The OFF bit must always be set to 0 when on-hook.
1 = DC termination disabled and the device presents an 800 Ω dc impedance to the line
which is used to enhance operation with an off-hook paralle l phone.
5OHS
On-Hook Speed (See Table 13 and “Appendix A—DAA Operation”).
0 = The Si2400 will execute a fast on-hook.
1 = The Si2400 will execute a slow, controlled on-hook.
4ACT
AC Termination (See Table 13 and “Appendix A—DAA Operation”).
0 = Real impedance.
1 = Complex impedance.
3:2 DCT DC Termination Voltage (See Table 13 and “Appendix A—DAA Operation”).
00 = Low Voltage Mode (transmit level = –5 dBm).
01 = Japan mode (transmit level = –3 dBm).
10 = USA mode (transmit level = –1 dBm).
11 = CTR21/France current limit mode (transmit level = –1 dBm).
1RZ
Ringer Impedance.
0 = Maximum (high) ringer impedance.
1 = Synthesize ringer impedance.
0RT
Ringer Threshold Select.
Used to satisfy country requirements on ring detection. Signals below the lower level will
not generate a ring detection; signals above the upper level are guaranteed to generate
a ring detection.
0 = 11 to 22 VRMS.
1 = 17 to 33 VRMS.
Si2400
Rev. 1.3 75
Reset settings = 0000_0000b (0x00)
SF6 (DAA6). DAA Low Level Functions 6
BitD7D6D5D4D3D2D1D0
Name FJM DIAL VOL FLVM
Type R/W R/W R/W
Bit Name Function
7:4 Reserved Read returns zero.
3FJM
Force Japan DC Termination.
0 = Normal mode.
1 = Force Japa n dc termination.
2DIAL
DTMF Dialing Mode.
This bit should be set during DTMF dialing in CTR21 mode if SDB (LVCS) < 12.
0 = Normal operation.
1 = Increase headroom for DTMF dialing.
1VOL
Line Voltage Adjust.
0=Nominal.
1 = Decreases dc termination voltage.
0FLVM
Force Low Voltage Mode.
When SF5[3:2] (DCT) = 10b (FCC mode), setting FLVM will force the Low Voltage mode
(see DCT = 00) while allowing for a transmit level of –1 dBm.
0 = Disable.
1 = Enable.
Si2400
76 Rev. 1.3
Reset settings = 0001_0000b (0x10)
SF7 (DAA7). DAA Low Level Functions 7
BitD7D6D5D4D3D2D1D0
Name LM0 LIM
Type R/W R/W
Bit Name Function
7:5 Reserved Read returns zero.
4 LM0 See LM0 in Register F0 page 71.
0
1
3LIMCurrent-Limiting Adjust Value.
0 = Disable.
1 = Enable (CTR21 mode).
2:0 Reserved Read returns zero.
SF8 (DAA8). DAA Low Level Functions 8
BitD7D6D5D4D3D2D1D0
Name LRV
Type R
Bit Name Function
7:4 LRV Line-Side Chip Revision Number.
1001 = Si3015 Rev A
1010 = Si3015 Rev B
1011 = Si3015 Rev C
1100 = Si3015 Rev D
3:0 Reserved Read returns ind eterministic.
Si2400
Rev. 1.3 77
Reset settings = 0010_0000b (0x20)
SF9 (DAA9). DAA Low Level Functions 9 Read Only
BitD7D6D5D4D3D2D1D0
Name OVL BTD ROV
Type RRR
Bit Name Function
7 Reserved Read returns zero.
6OVL
Receive Overload (see “Appendix A—DAA Operation”).
Same as ROV, except non-sticky.
5:4 Reserved Do Not Modify.
3BTD
Billing Tone Detect (sticky). (See “Appendix A—DAA Operation”.)
0 = No billing tone detected.
1 = Billing tone detected.
2 Reserved Read returns zero.
1ROV
Receive Overload (sticky) (see “Appendix A—DAA Operation”).
0 = No excessive level detected.
1 = Excessive input level detected.
0 Reserved Read returns zero.
Si2400
78 Rev. 1.3
APPENDIX A—DAA OPERATION
Introduction
This section describes the detailed functionality of the
integrated DAA included in the Si2400 chipset. This
specific functionality is generally transparent to the user
when using the on-chip controller in the Si2400 modem.
When bypassing the on-chip controller, the low-level
DAA functions of the Si3015 described in this section
can be controlled th ro ug h S reg ist er s.
DAA Isolation Barrier
The Si2400 chipset consists of the Si3015 line-side
device and the Si2400 modem device. The Si2400
achieves an isolation barrier through a low-cost, high-
voltage capacitor in conjunction with Silicon
Laboratories’ proprietary signal processing techniques.
These techniques eliminate any signal degradation due
to capacitor mismatches, common mode interference,
or noise couplin g. As show n in Fig u re 3 on page 10, the
C1, C4, C24, and C25 capacitors isolate the Si2400
(DSP-side) from the Si3015 (line-side). All transmit,
receive, and control data are communicated through
this barrier.
Emissions/Immunity
The Si2400 chipset and recommended DAA schematic
is fully compliant with and passes all international
electromagnetic emissions and conducted immunity
tests (includes FCC part 15,68; EN50082-1). Careful
attention to the Si2400 bill of materials (page 11),
schematic (Figure 3 on page 10), and layout guidelines
(included in the Si2400URT-EVB data sheet) will ensure
compliance with these international standards. In
designs with difficult layout constraints, the addition of
the C22 and C30 capacitors to the C24 and C25
recommended capacitors may improve modem
performan ce on em iss ion s an d co nd uc te d imm u nity.
Also, under some layout conditions, C22 and C30 may
improve the immunity to telephone line transients. This
is most important for applications that use the voice
codec feature of the Si2400. Becau se line tran sient s are
infrequent and high voltage in nature, they tend to be
more problematic in voice applications than in data
applications. An occasional pop in a voice application is
quite noticeable, whereas occasional bit errors are
easily corrected in a modem connection with an error-
correction protocol.
EN55022 and CISPR-22 Compliance
Compliance to the EN55022:1998 standard will be
necessary to conform to the European Union's EMC
Directive. Adherence to this standard will be necessary
to display the CE mark on designs intended for sale in
the EU. The deadline for EN55022 and CISPR-22
compliance is August 1, 2003. However, some non-
European countries currently require compliance to the
CISPR-22 specification. The typical schematic
(Figure 3) and global bill of materials (BOM) (page 11)
contained in this data sheet is designed to be compliant
to the above mentioned standards. It should be noted
that L1, L2, R31, R32, C38, and C39 are only necessary
for those products which are intended for sale in the
European Union or require CISPR-2 2 compliance. If this
is not the target market then L1 and L2 can be replaced
with 0 Ω resistors and R31, R32, C38, and C39 need
not be populated.
While this population option achieves EN55022 and
CISPR-22 compliance, there are several system
dependent and country dependent issues worth
considering. The first relates to the direct current
resistance (DCR) of the inductors. If the selected
inductors have a DCR of less than 3 Ω each, then
countries which require 300 Ω or less of dc resist ance at
TIP and RING with 20 mA of loop current can be
satisfied with the Japan dc termination mode (SF5[3:2]
[DCT] = 01b). If the selected inductors have a DCR of
greater than 3 Ω but less than 8 Ω each, then low
voltage dc termination mode (DCT = 00) must be used
to satisfy the above requirement. In either case, Silicon
Laboratories strongly recommends users of the
ISOmodem adhere to the section “DC Termination
Considerations” for dc termination requirements.
The second consideration re lates to the power supply of
the target system. The recommended values for L1, L2,
R31, R32, C38, and C39 assume that the target system
provides a direct current connection between the target
system's reference ground (Si2400 GND) and an
external ground (often the third prong of a power plug).
If there is no direct connection between the reference
ground and external ground, then smaller inductor
values are possible. It should be understood that this
consideration is system dependent, and the impedance
between the system ground and the external ground in
the range of 500 kHz and 10 MHz should be well
known. Please contact a Silicon Laboratories technical
representative for further assistance in analyzing or
testing systems for this consideration.
Si2400
Rev. 1.3 79
DC Termination
The Si2400 has four programmable dc termination
modes which are selected with SF5[3:2] (DCT).
FCC mode (DCT = 10b), shown in Figure 14, is the
default dc termination mode and supports a transmit full
scale level of –1 dBm at TIP and RING. This mode
meets FCC requir ements in a ddition to the requir ements
of many other countries.
Figure 14. FCC Mode I/V Characteristics
CTR21 mode DCT = 11b, shown in Figure 15, provides
current limiting while maintaining a transmit full scale
level of –1 dBm at TIP and RING. In this mode, the dc
termination will current limit before reaching 60 mA.
Figure 15. CTR21 Mode I/V Characteristics
Japan mode DCT = 01b, shown in Figure 16, is a lower
voltage mode and supports a transmit full scale level of
–2.71 dBm. Higher transmit levels for DTMF dialing are
also supported. See "DTMF Dialing" on page 80. The
low voltag e r equireme nt is dictated by countries such as
Japan and Malaysia.
Figure 16. Japan Mode I/V Characteristics
Low Voltage mode (DCT = 00b), shown in Figure 17, is
the lowest line voltage mode supported on the Si2400,
with a transmit full scale level of –5 dBm. Higher
transmit levels for DTMF dialing are also supported.
See “DTMF Dialing”. This low voltage mode is offered
for situations that require very low line voltage
operation. It is important to note that this mode should
only be used when necessary, as the dynamic range will
be significantly reduced and thus the ISOmodem will
not be able to transmit or receive large signals without
clipping them.
Figure 17. Low Voltage Mode I/V
Characteristics
12
11
10
9
8
7
6.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Loop Current (A)
FCC DCT Mode
V oltage A c ross DA A (V )
45
40
35
30
25
20
15
10
5
.015 .02 .025 .03 .035 .04 .045 .05 .055 .06
Loop Current (A )
CTR21 DCT M ode
V oltage A c ross DA A (V )
10.5
10
9.5
9
8.5
8
7.5
7
6.5
6
5.5.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Loop Current (A )
Japan DCT M ode
Voltage Across DAA (V)
10.5
10
9.5
9
8.5
8
7.5
7
6.5
6
5.5.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Loop Current (A )
Low V oltage M ode
Voltage Across DAA (V)
Si2400
80 Rev. 1.3
AC Termination
The Si2400 has two ac termination impedances,
selected with SF5[4] (ACT).
ACT = 0b is a real, nominal 600 Ω termination which
satisfies the impedance requirements of FCC part 68,
JATE, and other countries. This real impedance is set
by circuitry internal to the Si2400 chipset as well as the
resistor R2 connected to the Si3015 REXT pin.
ACT = 1b is a complex impedance which satisfies the
impedance requirements of Australia, New Zealand,
South Africa, CTR21 and some European NET4
countries such as the UK and Germany. This complex
impedance is set by circuitry internal to the Si2400
chipset as well as the network connected to the Si3015
REXT2 pin.
Ringer Impedance
The ring detector in a typical DAA is ac coupled to the
line with a large, 1 µF, 250 V decoupling capacitor. The
ring detector on the Si2400 is also capacitively coupled
to the line, but it is designed to use smaller, less
expensive 560 pF capacitors. Inherently, this network
produces a very high ringer impedance to the line on
the order of 800 to 900 kΩ. This value is acceptable for
most countries, including FCC and CTR21.
Several countries, including Poland, South Africa and
South Korea, requir e a m aximum rin ger impeda nce. Fo r
Poland, South Africa and South Korea, the maximum
ringer impedance specification can be met with an
internally synthesized impedance by setting SF5[1]
(RZ) = 1b.
DTMF Dialing
In CTR21 dc termination mode, set SF6[2] (DIAL) = 1b
during DTMF dialing if SDB (LVCS) ≤11. Setting this bit
increases headroom for large signals. This bit should
only be used during dialing and if SDB (LVCS) < 11.
In Japan dc termination mode (SF5[3:2] (DCT) = 01b),
the ISOmodem attenu ates the tr ansmit outpu t by 1.7 dB
to meet headroom requirements. Similarly, in Low
Voltage mode (DCT = 00b), the ISOmodem attenuates
the transmit output by 4 dB. However, when DTMF
dialing is desired in these modes, this attenuation must
be removed. This is achieved by entering the FCC dc
termination mode and setting SF6[3] (FJM) = 1b or
SF6[0] (FLVM) = 1. When in the FCC dc termination
modes, these bits will enable the respective lower loop
current termination modes without the associated
transmit attenuation. Increased distortion may be
observed, which is acceptable during DTMF dialing.
After DTMF dialing is complete, the attenuation should
be enabled by returning to either the Japan dc
termination mode (DCT = 01b) or the Low Voltage
termination mode (DCT = 00b). SF6[3] (FJM) and
SF6[0] (FLVM) have no effect in any other termination
mode other than the FCC dc termination mode.
Pulse Dialing
Pulse dialing is accomplished by going off and on hook
to generate make and break pu lse s. The no mina l rate is
10 pulses per second. Some countries have very tight
specifications for pulse fidelity, including make and
break times, make resistance, and rise and fall times. In
a traditional solid-state dc holding circuit, there are a
number of issues in meeting these requirements.
The Si2400 dc holding circuit has active control of the
on-hook and off-hook transients to maintain pulse
dialing fidelity.
Spark quenching requirements in countries such as
Italy, Netherlands, South Africa and Australia deal with
the on-hook transition during pulse dialing. These tests
provide an inductive dc feed, resulting in a large voltage
spike. This spike is caused by the line inductance and
the sudden decrease in current through the loop when
going on-hook. The traditional way of dealing with this
problem is to put a parallel RC shunt across the
hookswitch relay. The capacitor is large (~1 µF, 250 V)
and expensive. In the Si2400, SF5[6:5] (OHS) can be
used to slowly ramp down the lo op current to pass these
tests without requiring additional components.
Billing Tone Detection
“Billing tones” or “metering pulses” generated by the
central office can cause modem connection difficulties.
The billing tone is typically either a 12 KHz or 16 KHz
signal and is sometimes used in Germany, Switzerland,
and South Africa. Depending on line conditions, the
billing tone may be large enough to cause major modem
errors. The Si2400 chipset can provide feedback when
a billing tone occurs and when it ends.
Billing tone detection is enabled by setting SF1[7]
(BTE) = 1b. Billing tones less than 1.1 VPK on the line
will be filtered out by the low pass digital filter on the
Si2400. SF9[1] (ROV) is set when a line signal is
greater than 1.1 VPK, indicating a receive overload
condition. SF9[3] (BTD) is set when a line signal (billing
tone) is large enough to excessively reduce the line-
derived power supply of the line-side device (Si3015).
When the BTD bit is set, the dc termination is changed
to an 800 Ω dc impedance. This ensures minimum line
voltage levels even in the presence of billing tones.
The OVL bit should be polled following a billing tone
detection. When the OVL bit returns to zero, indicating
that the billing tone has passed, the BTE bit should be
written to zero to return the dc termination to its original
Si2400
Rev. 1.3 81
state. It will take approximately one second to return to
normal dc operating conditions. The BTD and ROV bits
are sticky, and they must be written to zero to be reset.
After the BTE, ROV, and BTD bits are all cleared, the
BTE bit can be set to reenable billing tone detection.
Certain line events, such as an off-hook event on a
parallel phone or a polarity reversal, may trigger the
ROV or the BTD bits, af ter which the billing tone detector
must be reset. The user should look for multiple events
before qualifying whether billing tones are actually
present.
Although the DAA will remain off-hook during a billing
tone event, the received data from the line will be
corrupted (or a modem disconnect or retrain may occur)
in the presence of large billing tones. If the user wishes
to receive data through a billing tone, an external LC
filter must be added. A modem manufacturer can
provide this filter to users in the form of a dongle that
connects on the phone line before the DAA. This keeps
the manufacturer from having to include a costly LC filter
internal to the modem when it may only be necessary to
support a few countries/customers.
Alternatively, when a billing tone is detected, the host
software may notify the user that a billing tone has
occurred. This notification can be used to prompt the
user to contact the telephone company and have the
billing tones disabled or to purchase an external LC filter.
Billing Tone Filter (Optional)
In order to operate without degradation during billing
tones in Germany, Switzerland, and South Africa, an
external LC notch filter is required. (The Si3015 can
remain off-hook during a billing tone event, but modem
data will be lost [or a modem disconnect or retrain may
occur] in the presence of large billing tone signals.) The
notch filter design requires two notc hes, one at 12 KHz
and one at 16 KHz. Because these components are
fairly expensive and few countries supply billing tone
support, this filter is typically placed in an external
dongle or added as a population option for these
countries. Figure 18 shows an example billing tone filter.
Figure 19 shows the billing tone filter and the ringer
impedance network for the Czech Republic. Both of
these circuits may be combined into a single external
dongle.
L3 must carry the entire loop current. The series
resistance of the inductors is important to achieve a
narrow and deep notch. This design has more than
25 dB of attenuation at both 12 KHz and 16 KHz.
Figure 18. Billing Tone Filter
‘
Figure 19. Dongle Applications Circuit
Table 29. Component Values—Optional Billing
Tone Filters
Symbol Value
C1,C2 0.027 μF, 50 V, ±10%
C3 0.01 μF, 250 V, ±10%
L3 3.3 mH, >120 mA, <10 Ω, ±10%
L4 10 mH, >40 mA, <10 Ω, ±10%
L4
C3
RING
TIP
FROM
LINE To
DAA
C1
C2
L3
TIP
RING
L3
3.3 mH, 120 mA
C1
0.027 F, 50 V
C2
0.027 F, 50 V
From
Line
To
Si3015
Chipset
L4
3.3 mH, 40 mA
C3
0.01 F, 250 V
Si2400
82 Rev. 1.3
The billing tone filter affects the ac termination and
return loss. The current complex ac termination will
pass worldwide return loss specifications both with and
without the billing tone filter by at least 3 dB. The ac
termination is optimized for frequency response and
hybrid cancellation, while having greater than 4 dB of
margin with or without the dongle for South Africa,
Australia, CTR21, German, and Swiss country-specific
specifications.
In-Circuit Testing
The Si2400’s advanced design provides the system
manufacturer with increased ability to determine system
functionality during production line test, as well as
support for end-user diagnostics.
The CLKOUT pin o f the Si2 400 can be used as a n initial
indication that the Si2400 is functional. Upon power up
and the negation of the reset pin, the CLKOUT pin
oscillates at 9.8304 MHz, which is twice the input clock
frequency of 4.9152 MHz. Testing the frequency of
CLKOUT indicates that the Si2400 internal clock is
operational. To test communication with the Si2400
across the UART, the local echo may be used
immediately after the part has been properly reset.
There are many methods to check to discover whether
the ISOCAP link between the Si2400 and Si3015 is
operational. These tests do not require any loop current
on the DAA. The first method is to check SF2[3] (FDT).
If it is set, the Si2400 and the Si3015 are
communicating. Another method is to read SF8[7:4]
(LRV) to verify the Si3015 is properly sending its version
number back to the Si2400. Finally, the voltage between
the Si3015 VREG pin and the IGND pin may be
measured and must exceed 3.6 V.
Once the clock, UART, and isolation link have been
proven to function, the production test can proceed to
verify operation of the discr ete component s mounted on
the board. In general, there are two approaches to
production line test. The first approach is to execute
complete modem connections through a commercially
available telephone line simulator. This approach is
simple to implement but incu rs a relatively long per unit
test time. If per unit test time is an important
consideration, another approach is to use the internal
tone generator on the Si2400 to generate a tone at TIP/
RING. The Si3015 can be programmed to disable the
hybrid (clearing SF1[2] [HBE]), thereby allowing the
transmitted signal to be looped b ack through the receive
path.
The Si2400 receives the loopback tone and should be
programmed to drive the tone to AOUT. This approach
requires loop current consistent with the equivalent
circuit shown in Figure 1.
As an example, the following string s can be sent to the
Si2400 to set up the 2225 Hz answer tone as the
stimulus waveform.
1. ATE0SF1=18SF7=00SF0=01 to go off hook and to disable
transmit hy bri d .
2. ATSE4=02M2SF4=03 to drive AOUT with the received
loopback tone from the line.
3. ATSE8=00SE6=00SE5=0BSE8=01SE6=08SE5=FCSE8=0
0 to set the tone amplitude to –12 dBm.
4. ATSE8=02SE5=04 S E6=02 to begin the 2225 Hz answer
tone.
With the above strings a number of points can be
probed to determine if the DAA is functioning properly.
Assuming a 30 mA loop current, the dc value of the TIP/
RING voltage should be in the neighborhood of 7.5 V.
The actual voltage is dependent on the chosen dc
Termination. Refer to Figures 14, 15, and 16.
The amplitude of the 2225 Hz tone on AOUT should be
around 500 mV peak-to-peak, corresponding to
amplitude consistent with a –12.9 dBm signal. The
digital filters introduce the 0.9 dBm attenuation. The
transmitted tone is set to a –12 dBm level so that when
the hybrid is disabled, an internal dc offset is realized.
The size of this dc offset is approximately half scale. To
guarantee no clipping under all conditions, a –12 dBm
maximum is recommended. If a slightly distorted signal
is acceptable on AOUT, a signal exceeding –12 dBm
may be implemented instead using the method shown
in step 3 above.
In order to complete the production test, it may be
necessary to simulate a ring signal. A sine wave pulse
of 500 ms with a 20 Hz frequency and an amplitude of
35 VRMS is sufficient for the Si2400 to return an “R”
result code. Additional production tests may be
employed to check the DAA. For example, a 300 V dc
test between TIP and RING can be used to ensure that
the hookswitch transistors are operational and are not
leaking any significant amount of current. Also, a HIPOT
(High Potential such as 1500 V) test applied
longitudinally between TIP/RING and GND can be used
to ensure that the isolation barrier is not bridged
inadvertently.
Si2400
Rev. 1.3 83
Compliance Test Commands
The following are compliance test commands:
ATS07=4ODT; // go off hook
ATSE8=05\r // place DSP in mode 5 (for QAM and DPSK)
ATSE5=xx\r // see notes below for setting xx
Writes to the ATSE5 register has the following effect when in DSP
Mode 5
bit 0 : transmit_ena set to 1 turns the transmitter on.
bit 2 : QAM/nDPSK
If 0, DPSK algorithm is chosen
If 1, QAM algorithm is chosen
bit 3 : orig/nans selects between originate mode and answer mode.
If 0, answer mode
If 1, originate mode
bit 4 : When set, enables 550 Hz guard tone
bit 5 : When set, enables 1800 Hz guard tone
ATSE6=00 // sending unscrambled zeros
ATSE6=FF // sending scarmbled ones
Si2400
84 Rev. 1.3
APPENDIX B—TYPICAL MODEM APPLICATIONS EXAMPLES
Introduction
Appendix B outlines the steps required to configure the
Si2400 for modem operation under typical examples.
The ISOmodem has been designed to be both easy to
use and flexible. The Si2400 has many features and
modes, which add to the complexity of the device, but
are not requ ired for a typical m odem configuratio n. The
goal of this appendix is to help the user to quickly make
a modem connection and begin evaluation of the
Si2400 under various op erational examples.
Example 1: V.22bis in FCC countries
1. Power on reset
2. Set Host UART to 2400 bps
3. ATS07=06 set for QAM 2400 bps
4. ATDT18005551212<CR>
Si2400 may echo the following:
t – tone dial detected
, – dialing complete
r – ringback
b – busy tone
N – No carrier
c – connect
d – connect at 1200bps
5. Next byte after “c” or “d” is modem data!
Example 2: V.22 in CTR21 countries
1. Power on reset
2. Set Host UART to 2400 bps with CTS flow control
3. ATS07=02 (set for DPSK 1200 bps)
4. ATSF5=1C (set DAA for CTR21)
5. ATSF7=18 (set DAA for CTR21)
6. ATDT18005551212<CR>
Si2400 may echo the following:
t – tone dial detected
, – dialing complete
r – ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Example 3: Bell 103 in Australia
1. Power on reset
2. Set Host UART to 2400 bps with CTS flow control
3. ATS07=01 (set for FSK 300 bps)
4. ATSF5=38 (set DAA for Australia)
5. ATDT18005551212<CR>
Si2400 may echo the following:
t – tone dial detected
, – dialing complete
r – ringback
b – busy tone
N – No carrier
c – connect
6. Next byte after “c” is modem data!
Example 4: Bell 103 in Australia with
Parallel Phone Detect
1. Power on reset
2. Set Host UART to 2400 bps with CTS flow control
3. ATS07=01 (set for FSK 300 bps)
4. ATSF5=38 (set DAA for Australia)
5. ATSE2=C0 (enable ALERT pin)
6. ATDT18005551212<CR>
Si2400 may echo the following:
t – tone dial detected
, – dialing complete
r – ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Example 5: Bell 212A in South Korea with
Japanese caller ID
1. Power on reset
2. Set Host UART to 2400 bps with CTS flow control
3. ATS07=00 (set for DPSK 1200 bps)
4. ATSF5=06(set DAA for So uth Korea)
5. ATS13=80 (set caller ID to Japanese format)
When caller ID data is detected, Si2400 will echo “f”
indicating the line reversal, “m” indicating the mark, and
then caller ID data will follow.
6. ATDT18005551212<CR>
-Si2400 may echo:
t – tone dial detected
, – dialing complete
r – ringback
b – busy tone
N – No carrier
c – connect
7. Next byte after “c” is modem data!
Si2400
Rev. 1.3 85
APPENDIX C—UL1950 3RD EDITION
Designs using the Si2400 pass all overcurrent and
overvoltage tests for UL1950 3rd Edition compliance
with a couple of considerations.
Figure 20 shows the designs that can pass the UL1950
overvolta ge tests, as well as electroma gnetic emissions.
The top schem atic of Figure 20 shows the c onfigur ation
in which the ferrite beads (FB1, FB2) are on the
unprotected side of the sidactor (RV1). For this
configuration, the current rating of the ferrite beads
must be 6 A.
The bottom schematic of Figure 20 shows the
configuration in which the ferrite beads (FB1, FB2) are
on the protected side of the sidactor (RV1). For this
design, the ferrite beads can be rated at 200 mA.
In a cost-optimized design, it is important to remember
that compliance to UL1950 does not always require
overvoltage tests. It is best to plan ahead and know
which overvoltage tests will apply to your system.
System-level elements in the construction, such as fire
enclosure and spacing requirements, need to be
considered during the design stages. Consult with your
Professional Testing Agency during the design of the
product to determine which tests apply to your system.
Figure 20. Circuits that Pass all UL1950 Overvoltage Tests
Note: In this configuration, C24 and C 25 are used for
em issions testing.
C24
RV1
C25
TIP
RING
Fuse/PTC
FB1
FB2
1.25 A 75 Ω @ 100 M Hz, 6A
C24
FB1
FB2
C25
RV1
Fuse/PTC
TIP
RING
1.25 A
1000 Ω @ 100 M Hz, 200 m A
75 Ω @ 10 0 MH z, 6A
1000 Ω @ 100 M Hz, 200 m A
Si2400
86 Rev. 1.3
9. Pin Descriptions: Si2400
Pin # Pin Name Description
1XTALI XTALI—Crystal Oscillator Pin.
These pins provide suppo rt for parallel resonant, AT cut crystals. XTALI also acts as
an input in the event that an external clock source is used in place of a crystal.
2XTALO XTALO—Crystal Oscillator Pin.
Serves as the output of the crystal amplifier. A 4.9152 MHz crystal is required or a
4.9152 MHz clock on XTALI.
3CLKOUT Clock Output.
This signal is typically used to clock an output system microcontroller. The frequency
is 78.6432 MHz/(N+1), where N is programmable from 0 to 31. N defaults to 7 on
power up. Settin g N = 0 stops the clock.
4VD Digital Supply Voltage.
Provides the digital supp ly voltage to the Si2400. Nominally either 5 V or 3.3 V.
5RXD Receive Data.
Serial communication data from the Si2400.
6TXD Transmit Data.
Serial communication data to the Si2400.
7CTS Clear to Send.
Clear to send output used by the Si2400 to signal that the device is ready to receive
more digit al data on the TXD pin.
8RESET Reset Input.
An active low input that is used to reset all control registers to a defined, initialized
state. Also used to bring the Si2400 out of sleep mode.
9AOUT Analog Speaker Output.
Provides an analog output signal for monitoring call progress tones or to output voice
data to a speaker.
1
2
3
4
5
6
7
89
10
11
12
13
16
15
14
GPIO1
GPIO2
GPIO3
ISOB
GND
C1A
GPIO4
AOUT
XTALI
XTALO
CLKOUT
VD
RXD
TXD
CTS
RESET
Si2400
Rev. 1.3 87
10 GPIO4 General Purpose Input/Output 4.
This pin can be either a GPIO pin (analog in, digital in, digital out) or the ALERT pin.
Default is digital in. When progr ammed as ALERT, this pin provides five functions.
While the modem is connected, it will normally be low, but will go high if the carrier is
lost, a wake-on ring (using the “ATZ” command) event is detected, a loss of loop cur-
rent event is detected, V.23 reversal is detected, or if an intrusion event has been
detected. The ALERT pin is sticky, and will stay high until the host clears it by writing
to the correct S register. (See register SE2[7:6].)
11 C1A Isolation Capacitor 1A.
Connects to one side of the isolation capacito r C1.
12 GND Ground.
Connects to the system digital ground.
13 ISOB Bias Voltage.
This pin should be connected via the C3 capacitor.
14 GPIO3 General Purpose Input/Output 3.
This pin can be either a GPIO pin (analog in, digital in, digital out) or the ESC pin.
Default is digital in. When programmed as ESC, a positive edge on this pin will cause
the modem to go from online (connected) mode to the offline (command) mode.
15 GPIO2 General Purpose Input/Output 2.
This pin can be either a GPIO pin (analog in, digital in, digital out) or the TXD2 pin.
Default is digital in. The user can program this pin to function as TXD2 if the second-
ary serial interface is enabled. This pin is also used as the active low carrier detect pin
(CD) if enabled via the CDE bit in (S0C.7).
16 GPIO1 General Purpose Input Output 1.
This pin can be either a GPIO pin (analog in, digital in, digital out) or the RXD2 pin.
Default is digital. The user can program this pin to function as RXD2 if the secondary
serial interface is enabled. This pin can also be pr ogrammed to function as the EOFR
(end of frame receive) signal for HDLC framing.
Pin # Pin Name Description
Si2400
88 Rev. 1.3
10. Pin Descriptions: Si3015
Table 30. 3015 Pin Descriptions
Pin # Pin Name Description
1QE2Transistor Emitte r 2.
Connects to the emitter of Q4.
2 DCT DC Termination.
Provides dc termination to the telephone network
3IGND
Isolated Ground.
Connects to ground on the line-side interface. Also connects to capacitor C2.
4C1B
Isolation Capacitor 1B.
Connects to one side of isolation capacitor C1.
5RNG1
Ring 1.
Connects through a capacitor to the TIP lead of the telephone line. Provides the ring
and caller ID signals to the Si2400.
6RNG2
Ring 2.
Connects throu gh a capacitor to the RING le ad of the telephone lin e. Provides the ring
and caller ID signals to the Si2400.
7QB
Transistor Base.
Connects to the base of transistor Q3.
8QE
Tra n si st or Emit te r.
Connects to the emitter of Q3.
9VREG
Voltage Regulator.
Connects to an external capacitor to provide bypassing for an internal power supply.
10 VREG2 Volta g e Regulator 2.
Connects to an external capacitor to provide bypassing for an internal power supply.
11 REF Reference.
Connects to an external resistor to provide a high accuracy reference current.
12 REXT2 External Resistor 2.
Sets the complex ac termination impedance.
13 REXT External Resistor.
Sets the real ac termination impedance.
1
2
3
4
5
6
7
89
10
11
12
13
16
15
14
QE2
DCT
IGND
C1B
RNG1
RNG2
QB
QE
FILT2
FILT
RX
REXT
REXT2
REF
VREG2
VREG
Si2400
Rev. 1.3 89
14 RX Receive Input.
Serves as the receive side input from the telephone network.
15 FILT Filter.
Provides filtering for the dc termination circuits.
16 FILT2 Filter 2.
Provides filtering for the bias circui ts.
Table 30. 3015 Pin Descriptions (Continued)
Pin # Pin Name Description
Si2400
90 Rev. 1.3
11. Ordering Guide
Chipset Region System-Side Line-Side Pb-Free Temp. Range
Si2400 Global Si2400-KS Si3015-KS No 0 to 70 °C
Si2400 Global Si2400-BS Si3015-BS No –40 to 85 °C
Si2400 Global Si2400-FS Si3015-F-FS Yes 0 to 70 °C
Si2400
Rev. 1.3 91
12. Package Outline: 16-Pin SOIC
Figure 21 illustrates the package details for the Si2400 and Si3015. Table 31 lists the values for the dimensions
shown in the illustration.
Figure 21. 16-pin Small Outline Integrated Circuit (SOIC) Package
Table 31. Package Diagram Dimensions
Symbol Millimeters
Min Max
A 1.35 1.75
A1 .10 .25
B.33.51
C.19.25
D 9.80 10.00
E 3.80 4.00
e 1.27 BSC
H 5.80 6.20
h.25.50
L .40 1.27
γ0.10
θ0º 8º
aaa 0.25
bbb 0.25
E H
A1
B
C
h
L
θ
e
See Detail F
Detail F
A
16 9
8
1
D
Seating Plane γ
-B- Bbbb
-A-
BACaaa
-C-
Approximate device weight is 152 mg.
Si2400
92 Rev. 1.3
DOCUMENT CHANGE LIST
Revision 1.1 to Revision 1.2
Table 3 on page 6, GPIO1–4 (VOL) changed to
20 mA.
Table 4 on page 6, GPIO1–4 (VOL) changed to
15 mA.
Table 5 on page 7, Caller ID Common Mode
Tolerance added.
Updated !7, !1 descr ipt i on of page 34.
Added "Compliance Test Commands" on page 83.
Register S33 (MDMO)., “Mode m Over ride,” on page
57, bit 0 (TSAL) defini tio n corr ected.
Updated "11.Ordering Guide" on page 90.
SOIC outline updated.
Revision 1.2 to Revision 1.3
Updated "11.Ordering Guide" on page 90.
Si2400
Rev. 1.3 93
NOTES:
Si2400
94 Rev. 1.3
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