CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CMX7032
CMX7042
AIS Data Processor
2011 CML Microsystems Plc
D/7032/42_FI1.2/12 October 2011
DATASHEET
Provisional Issue
Marine AIS data processor designed for Limiter-Discriminator based RF systems
Features:
Half-Duplex GMSK and FSK Modem
Low-Power (3.0V to 3.6V) Operation
AIS and DSC Data Format
Limiter-Discriminator Rx Interface
Optimum Co-channel and Adjacent-channel
Performance
Flexible Tx Interface: I/Q or Two-
point Modulation
Flexible Channel Configuration:
– Two Simultaneous Rx
– One Tx
Auxiliary ADC and DAC Functions
– 4 x (10-bit) DACs
– 2 x (10-bit) ADCs
Supports Carrier-Sensing Channel Access
(CSTDMA) Operation
Applications:
Low Profile 64 or 48 pad Leadless VQFN and
64 or 48 pin LQFP Packages
Automatic Identification System
(AIS) for Marine Safety
Configurable by Function Image™
AIS Aids-To-Navigation (AtoN)
Two RF Synthesisers (CMX7032 only)
AIS Class B Transponders
Two Auxiliary System Clock Generators
AIS Rx-only or Tx-only Modules
Rx2:
Limiter-
Discriminator
Rx1:
Limiter-
Discriminator
Tx:
I/Q or
2-point
Output
Drivers
GMSK
Encoder
GMSK
Decoder
Message
Buffer
HDLC
NRZI
Encoder
ADCs
DACs
Reset and
Pow er
control
Sample
Timer
Interrupt
Generator
C-BUS
Interface
GMSK
Decoder
FSK
Decoder
Message
Buffer
Mesage
Buffer
HDLC
NRZI
Decoder
HDLC
NRZI
Decoder
Mesage
Buffer
Rx Section
Tx Section
Dual RF Synthesisers
(CMX7032 only)
CMX7032
CMX7042
Dual Clock Generators Auxiliary
Section
AIS
Radio
Tranceiver
TCXO
Host
Micro
GPIO
Datasheet
User
Manual
This document contains:
Brief description, see next page…
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 2 D/7032/42_FI1.2/12
1 Brief Description
The highly integrated Baseband Signalling Processor ICs CMX7032 and CMX7042 fulfil the requirements
of the Class B Marine Automatic Identification System (AIS) transponder market. The CMX7042 is
identical in functionality to the CMX7032 with the exception that the two on-chip RF Synthesisers have
been deleted, which enables it to be supplied in a smaller package. This document refers to both parts
generically as the CMX7032/CMX7042, unless otherwise stated.
The AIS system allows ships and base stations to communicate their position and other data to each other
without the need for a centralised controller. This allows vessels to “see” each other and take appropriate
action to avoid collision and so improve marine safety. The system uses a GMSK 9600 baud data link in
the Marine VHF radio band. The system requirements are defined in ITU-R M.1371-4.
The CMX7032/CMX7042 devices utilise CML’s proprietary FirmASIC component technology. On-chip
sub-systems are configured by a Function Image™: this is a data file that is uploaded during device
initialization which defines the device's function and feature set. The Function Image™ can be loaded
automatically from an external serial memory or from a host µController over the built-in C-BUS serial
interface. The device's functions and features can be enhanced by subsequent Function Image™
releases, facilitating in-the-field upgrades.
The CMX7032/CMX7042, when used with 7032/7042FI-1.x, is half duplex in operation, comprising two
parallel Limiter-Discriminator Rx paths and one I/Q or two-point modulation Tx path. The Rx paths are
configurable for AIS or DSC operation, the Tx for AIS only. The device performs signal
modulation/demodulation with associated AIS functions, such as training sequence detection, NRZI
conversion and HDLC processing (flags, bit stuffing/de-stuffing, CRC generate/check). Integrated Rx/Tx
data buffers are also provided. This greatly reduces the processing requirements of the host µC. Provision
of a number of auxiliary ADCs and DACs further simplifies the system hardware design, reducing the
overall equipment cost and size. This document refers specifically to the features provided by the
CMX7032/CMX7042 Function Image™ FI-1.2.
This Datasheet is the first part of a two-part document comprising Datasheet and User Manual: the User
Manual can be obtained by registering your interest in this product with your local CML representative.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 3 D/7032/42_FI1.2/12
CONTENTS
1 Brief Description ............................................................................................................................... 2
1.1 History ........................................................................................................................................ 5
2 Block Diagram ................................................................................................................................... 7
3 Signal List .......................................................................................................................................... 8
3.1 Signal Definitions ..................................................................................................................... 11
4 Recommended External Components .......................................................................................... 12
5 PCB Layout Guidelines and Power Supply Decoupling .............................................................. 15
6 General Description ........................................................................................................................ 17
6.1 Overview .................................................................................................................................. 17
6.2 AIS system formats ................................................................................................................. 18
7 Detailed Descriptions ...................................................................................................................... 19
7.1 Clock Source ........................................................................................................................... 19
7.2 Host Interface .......................................................................................................................... 19
7.3 Function Image™ Load and Activation .................................................................................... 21
7.3.1 FI Loading from Host Controller ................................................................................... 21
7.3.2 FI Loading from Serial Memory .................................................................................... 23
7.4 System Description and Tasks ................................................................................................ 24
7.4.1 Signal Routing .............................................................................................................. 24
7.4.2 Operating Modes ......................................................................................................... 24
7.4.3 Modem and Data Units ................................................................................................ 24
7.4.4 Timing and Synchronisation ......................................................................................... 25
7.4.5 Time of Arrival Reporting ............................................................................................. 25
7.4.6 Tx Timing ..................................................................................................................... 25
7.4.7 Rx Timing ..................................................................................................................... 26
7.4.8 CSTDMA Threshold Measurement .............................................................................. 27
7.4.9 RSSI Measurement ...................................................................................................... 27
7.4.10 RSSI Calibration ........................................................................................................... 28
7.4.11 ADCs ............................................................................................................................ 28
7.4.12 DACs ............................................................................................................................ 28
7.4.13 Interrupt Operation ....................................................................................................... 28
7.4.14 Deep Sleep Mode ........................................................................................................ 28
7.5 Operation of Tasks .................................................................................................................. 28
7.5.1 Tx Task Operation ....................................................................................................... 29
7.5.2 Rx Task Operation ....................................................................................................... 30
7.5.3 Registers and Buffers for Tx/Rx Tasks ........................................................................ 31
7.5.4 Write Data Registers .................................................................................................... 31
7.5.5 Read Data Registers .................................................................................................... 32
7.5.6 Data Tasks ................................................................................................................... 32
7.5.7 Modem Tasks and Codes ............................................................................................ 33
7.6 Transmission format ................................................................................................................ 33
7.6.1 Transmit Tasks ............................................................................................................ 34
7.6.2 AIS Burst Mode Transmit ............................................................................................. 34
7.6.3 Transmit Example ........................................................................................................ 35
7.6.4 AIS Raw Mode Transmit .............................................................................................. 35
7.6.5 Transmitter Timing Control .......................................................................................... 35
7.6.6 Modulation Formats ..................................................................................................... 37
7.7 Reception ................................................................................................................................. 38
7.7.1 AIS Burst Mode Receive .............................................................................................. 38
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 4 D/7032/42_FI1.2/12
7.7.2 AIS Raw Mode Receive ............................................................................................... 40
7.7.3 DSC Receive................................................................................................................ 40
7.7.4 Receive Example ......................................................................................................... 42
7.7.5 Rx Tasks ...................................................................................................................... 42
7.8 Configuration Tasks and Codes .............................................................................................. 43
7.9 RF Synthesiser (CMX7032 only) ............................................................................................. 44
7.10 System Clock Synthesisers ..................................................................................................... 47
7.11 Powersave ............................................................................................................................... 48
7.12 C-BUS Register Summary ....................................................................................................... 49
8 Performance Specification ............................................................................................................. 50
8.1 Electrical Performance ............................................................................................................ 50
8.1.1 Absolute Maximum Ratings ......................................................................................... 50
8.1.2 Operating Limits ........................................................................................................... 51
8.1.3 Operating Characteristics ............................................................................................ 52
8.1.4 Parametric Performance .............................................................................................. 56
8.2 C-BUS Timing .......................................................................................................................... 57
8.3 SPI Timing ............................................................................................................................... 58
8.4 Packaging ................................................................................................................................ 59
TABLES
Table 1 Definition of Power Supply and Reference Voltages ..................................................................... 11
Table 2 Component Values ........................................................................................................................ 14
Table 3 BOOTEN Pin States ...................................................................................................................... 21
Table 4 Data Tasks .................................................................................................................................... 32
Table 5 Modem Tasks................................................................................................................................ 33
Table 6 AIS Burst Transmit Example ......................................................................................................... 35
Table 7 Tx Sequence events ..................................................................................................................... 36
Table 8 Example Tx Event Sequence Setup ............................................................................................. 37
Table 9 Tx Spectrum Masks ...................................................................................................................... 38
Table 10 AIS Burst Receive Example ........................................................................................................ 42
Table 11 Configuration Tasks .................................................................................................................... 43
Table 12 C-BUS Registers ......................................................................................................................... 49
FIGURES
Figure 1 CMX7032/CMX7042 Block Diagram .............................................................................................. 7
Figure 2 CMX7032 Recommended External Components ........................................................................ 12
Figure 3 CMX7042 Recommended External Components ........................................................................ 13
Figure 4 CMX7032 Power Supply Connections and De-coupling .............................................................. 15
Figure 5 CMX7042 Power Supply Connections and De-coupling .............................................................. 16
Figure 6 C-BUS Transactions .................................................................................................................... 20
Figure 7 FI Loading from Host ................................................................................................................... 22
Figure 8 FI Loading from Serial Memory .................................................................................................... 23
Figure 9 Tx Burst Timing ............................................................................................................................ 26
Figure 10 Rx Burst Timing ......................................................................................................................... 27
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 5 D/7032/42_FI1.2/12
Figure 11 Tx Task Operation ..................................................................................................................... 29
Figure 12 Rx Task Operation ..................................................................................................................... 30
Figure 13 Typical AIS Transmission .......................................................................................................... 36
Figure 14 DSC Format ............................................................................................................................... 41
Figure 15 Example RF Synthesiser Components ...................................................................................... 44
Figure 16 Single RF PLL Block Diagram ................................................................................................... 45
Figure 17 System Clock Generation .......................................................................................................... 47
Figure 18 C-BUS Timing ............................................................................................................................ 57
Figure 19 SPI Interface Timing .................................................................................................................. 58
Figure 20 Mechanical Outline for 64-pad VQFN Package (Q1) ................................................................. 59
Figure 21 Mechanical Outline for 64-pin LQFP (leaded) Package (L9) ..................................................... 59
Figure 22 Mechanical Outline for 48-pad VQFN Package (Q3) ................................................................. 60
Figure 23 Mechanical Outline for 48-pin LQFP (leaded) Package (L4) ..................................................... 60
It is always recommended that you check for the latest product datasheet version from the
Datasheets page of the CML website: [www.cmlmicro.com].
1.1 History
Version
Changes
Date
12
Add CRC disable feature.
Add CS-Sync output.
Add SlotCLK output.
Changed EEPROM references to serial memory
07/10/11
11
Update to RF Synthesiser paramaters, following evaluation.
Correction of errors in $C8 Command Register Table.
Further Information on Status2 ($C5) Register.
Clarification of BOOTEN options by Table 13 and Table 3.
Correction of error in Figure 8.
Update to Modulation Notes (section 11.1) and clarification of Figure 26.
29/7/11
10
Addition of operating voltage range clarification (3.0V to 3.6V) into History files
Addition of revised Function Image™ flowcharts (Fig 7 and 8) into History files
18/9/09
9
Correction to HCT in Task table: should be $2E not $0E
HCT $A7 settings removed from Modem Task table. This information is present
in the table immediately below.
Addition of update to register $CE b8 description into History files
Remove ac coupling from component diagrams - should always be dc coupled
Clarification of the power-up and reset conditions
Addition of a hyperlinked table in section 10, in place of C-BUS Register Map
Minor style changes and correction of typographical errors
11/9/09
8
NRZI encoder re-initialised on every Tx burst.
Slot initialization range corrected from 2250 to 2249
Modem tasks table in section 11.18 corrected (Tx AIS raw / Tx AIS unscheduled)
Table 1 Note 6 clarified.
15/6/09
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 6 D/7032/42_FI1.2/12
7
C-BUS names standardised
AuxADC and AuxDAC changed to ADC and DAC
SpareADC changed to Spare
Standards references updated
Slot Counter and ToA compensation and description added: 7.4.5, 7.7.5, table 10
RSSI1 & 2 periods shown separately in fig 10
Contact details updated
13/05/09
6
Addition of C-BUS Mode pin (CMX7032 only), omitted from version 5.
Clarification of operation of DSC Raw and Formatted Modes.
Clarification of RF PLL description: 'channel' replaced by 'PLL'.
Updated parametric figures, based on device characterisation.
Corrections and updates to C-BUS Register Map.
Addition of DSC Format Enable flag into Command register ($C8) bit 6.
Section 9.19.7 clarification: 'polarity' should refer to the 'initial state'.
Correction of typographical errors and incorrect hyperlinks.
4/12/08
5
Original document, prepared for release of FI-1.2.1.1
14/1/08
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 7 D/7032/42_FI1.2/12
2 Block Diagram
Buffer HDLC
Encode
Tx GMSK
AIS
Transmit Functions
NRZI
Encode
GMSK
Encode
RX2FB
RX1FB
RSSI1
RSSI2
ADC1
ADC2
DAC1
EPSCLK
BOOTEN1
BOOTEN2
TXENA
SLOTCLK
EPSCSN
Input 1
C-BUS
Interface
Power Control
Registers IRQN
RDATA
CSN
CDATA
SCLK
System Clock 2
System Clock 1
Synthesiser
2CP2OUT
RF2P
RFVDD
ISET2
CPVDD
RFVSS
RFCLK
SYSCLK 1
SYSCLK 2
ADC 2
ADC 1
Ramp Profile
RAM
DAC 1
DAC 2
DAC 3
DAC 4
DAC2
DAC3
DAC4
Reg
DVDD
VDEC
DVSS
AVDD
VBIAS
AVSS
Crystal
Oscillator
XTAL/CLK
XTALN
GPIO
EEPROM
SPI port
EPSI
EPSO
Auxiliary Functions
Boot
Control
MUX
Synthesiser
1
RF1N
ISET1
CP1OUT
Auxiliary
Multiplexed
ADCs
Auxiliary DACs
General
Purpose I/O
RF Synthesisers
(CMX7032 only)
Auxiliary
System
Clocks
System Control
Bias
Internal Systems
Control
Main Clock
Digital PLL
Internal Signal
GMSK
Decode
NRZI
Decode
HDLC
Decode Buffer Rx1 GMSK
AIS
FSK
Decode Buffer FSK- DSC
NRZI
Decode Buffer
HDLC
Decode
Rx2 GMSK
AIS
GMSK
Decode
MOD1
MOD2
VBIAS
VBIAS
Input 2
VBIAS
SpareFB
Mux
CBUSMODE
(CMX7032
only)
Receive Functions
RX1N
RX2N
SpareN
RF2N
RF1P
CS-SYNC
SLOTCLKOP
Figure 1 CMX7032/CMX7042 Block Diagram
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 8 D/7032/42_FI1.2/12
3 Signal List
CMX7032
64-pin
Q1/L9
CMX7042
48-pin
Q3/L4
Signal
Name
Type
Description
1
8
IRQN
OP
C-BUS: A 'wire-ORable' output for connection to the
Interrupt Request input of the host. Pulled down to DVSS
when active and is high impedance when inactive. An
external pull-up resistor (R1) is required.
2
-
RF1N
IP
RF Synthesiser #1 Negative input.
3
-
RF1P
IP
RF Synthesiser #1 Positive input.
4
-
RFVSS
PWR
The negative supply rail (ground) for the RF synthesisers.
5
-
CP1OUT
OP
1st Charge Pump output.
6
-
ISET1
IP
1st Charge Pump Current Set input.
7
-
RFVDD
PWR
The 2.5V positive supply rail for the RF synthesisers. This
should be decoupled to RFVSS by a capacitor mounted
close to the device pins.
8
-
RF2N
IP
RF Synthesiser #2 Negative input.
9
-
RF2P
IP
RF Synthesiser #2 Positive input.
10
-
RFVSS
PWR
The negative supply rail (ground) for the 2nd RF
synthesiser.
11
-
CP2OUT
OP
2nd Charge Pump output.
12
-
ISET2
IP
2nd Charge Pump Current Set input.
13
-
CPVDD
PWR
The 3.3V positive supply rail for the RF charge pumps. This
should be decoupled to RFVSS by a capacitor mounted
close to the device pins.
14
-
RFCLK
IP
RF Clock Input (common to both synthesisers)1.
15
-
CS-SYNC
OP
Pulse output when device is about to Tx.
16
-
SLOTCLKOP
OP
Internal SlotCLK output
17
-
-
NC
Reserved – do not connect this pin.
18
9
VDEC
PWR
Internally generated 2.5V digital supply voltage. Must be
decoupled to DVSS by capacitors mounted close to the
device pins. No other connections allowed, except for
optional connection to RFVDD.
19
10
SLOTCLK
IP
Slot Clock from host (37.5Hz).
-
11
CS-SYNC
OP
Pulse output when device is about to Tx.
-
12
SLOTCLKOP
OP
Internal SlotCLK output
20
13
SYSCLK1
OP
Synthesised Digital System Clock Output 1.
21
14
DVSS
PWR
Digital Ground.
22
-
-
NC
Reserved – do not connect this pin.
23
15
TXENA
OP
Enable for external Tx hardware.
1
To minimise crosstalk, this signal should be connected to the same clock source as XTAL/CLK input. By
default, this is connected internally at power-on, alternatively, this may be achieved by connecting the pin
to the XTALN output when a 19.2MHz source is in use.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 9 D/7032/42_FI1.2/12
CMX7032
64-pin
Q1/L9
CMX7042
48-pin
Q3/L4
Signal
Name
Type
Description
24
16
RX1N
IP
Rx1 inverting input.
25
17
RX1FB
OP
Rx1 input amplifier feedback.
26
18
RX2N
IP
Rx2 inverting input.
27
19
RX2FB
OP
Rx2 input amplifier feedback.
28
20
SpareFB
OP
Spare input amplifier feedback.
29
21
SpareN
IP
Spare inverting input.
30
22
AVSS
PWR
Analogue Ground.
31
23
MOD1
OP
Modulator 1 output.
32
24
MOD2
OP
Modulator 2 output.
33
25
VBIAS
OP
Internally generated bias voltage of about AVDD/2, except
when the device is in ‘Powersave’ mode when VBIAS will
discharge to AVSS. Must be decoupled to AVSS by a
capacitor mounted close to the device pins. No other
connections allowed.
34
26
-
NC
Reserved – do not connect this pin.
35
27
RSSI1
IP
Analogue RSSI input from Limiter / Discriminator 1.
36
28
RSSI2
IP
Analogue RSSI input from Limiter / Discriminator 2.
37
29
ADC1
IP
ADC input 1.
38
30
ADC2
IP
ADC input 2.
39
31
AVDD
PWR
Analogue +3.3V supply rail. Levels and thresholds within the
device are proportional to this voltage. This pin should be
decoupled to AVSS by capacitors mounted close to the
device pins.
40
32
DAC1
OP
DAC output 1/RAMDAC.
41
33
DAC2
OP
DAC output 2.
42
34
AVSS
PWR
Analogue Ground.
43
35
DAC3
OP
DAC output 3.
44
36
DAC4
OP
DAC output 4.
-
37
DVSS
PWR
Digital Ground.
45
38
VDEC
PWR
Internally generated 2.5V supply voltage. Must be decoupled
to DVSS by capacitors mounted close to the device pins. No
other connections allowed, except for the optional
connection to RFVDD.
46
39
XTAL/CLK
IP
19.2MHz input from the external clock source or 9.6MHz
Xtal.
47
40
XTALN
OP
The output of the on-chip 9.6MHz Xtal oscillator inverter. NC
if 19.2MHz Clock used.
48
41
DVDD
PWR
Digital +3.3V supply rail. This pin should be decoupled to
DVSS by capacitors mounted close to the device pins.
49
42
CDATA
IP
C-BUS: Command Data. Serial data input from the µC.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 10 D/7032/42_FI1.2/12
CMX7032
64-pin
Q1/L9
CMX7042
48-pin
Q3/L4
Signal
Name
Type
Description
50
43
RDATA
TS OP
C-BUS: Reply Data. A 3-state C-BUS serial data output to
the µC. This output is high impedance when not sending
data to the µC.
51
44
-
NC
Reserved – do not connect this pin.
52
45
DVSS
PWR
Digital Ground.
53
-
-
NC
Reserved – do not connect this pin.
54
46
SCLK
IP
C-BUS: The C-BUS serial clock input from the µC.
55
47
SYSCLK2
OP
Synthesised Digital System Clock Output 2.
56
48
CSN
IP
C-BUS: The C-BUS chip select input from the µC.
57
-
CBUSMODE
IP+PD
Reserved – connect to DVSS (CMX7032 only).
58
1
EPSI
OP
Serial Memory Interface:SPI bus Output.
59
2
EPSCLK
OP
Serial Memory Interface:SPI bus Clock.
60
3
EPSO
IP+PD
Serial Memory Interface:SPI bus Input.
61
4
EPSCSN
OP
Serial Memory Interface:SPI bus Chip Select.
62
5
BOOTEN1
IP+PD
Used in conjunction with BOOTEN2 to determine the
operation of the bootstrap program.
63
6
BOOTEN2
IP+PD
Used in conjunction with BOOTEN1 to determine the
operation of the bootstrap program.
64
7
DVSS
PWR
Digital Ground.
EXPOSED
METAL
PAD
EXPOSED
METAL
PAD
SUB
~
On Q1 and Q3 packages only, the central metal pad may be
connected to Analogue Ground (AVSS) or left unconnected.
No other electrical connection is permitted.
Notes:
IP = Input (+PU/PD = internal pullup/pulldown resistor)
OP = Output
TS OP = 3-state Output
PWR = Power Supply Connection
NC = No Connection
Functions with no associated pin number are not available in the CMX7042.
SLOTCLKOP and CS-SYNC functions are not available on CMX7032 devices with
batch codes before #72181.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 11 D/7032/42_FI1.2/12
3.1 Signal Definitions
Table 1 Definition of Power Supply and Reference Voltages
Signal
Name
Pins
Usage
AVDD
AVDD
Power supply for analogue circuits
DVDD
DVDD
Power supply for digital circuits
RFVDD
RFVDD
Power supply for RF synthesiser circuits
CPVDD
CPVDD
Power supply for RF charge pump
VDEC
VDEC
Power supply for core logic, derived from DVDD by on-chip regulator
VBIAS
VBIAS
Internal analogue reference level, derived from AVDD
AVSS
AVSS
Ground for all analogue circuits
DVSS
DVSS
Ground for all digital circuits
RFVSS
RFVSS
Ground for all RF circuits
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 12 D/7032/42_FI1.2/12
4 Recommended External Components
ADCs
DACs
C-BUS
25 C7
DAC2
DAC1
VDEC
VDEC
ADC2
RSSI2
AVDD
DVDD
DVDD
AVDD
XTAL/CLK
ADC1
RSSI1
IRQN
XTALN
DVSS
DVSS
AVSS AVSS
DVSS
DVSS
DVSS
AVSS
DVDD
SYSCLK2
VBIAS
CDATA (COMMAND DATA)
SCLK (SERIAL CLOCK)
RDATA (REPLY DATA)
CSN
CBUSMODE
n/c
n/c
SLOTCLKOP
CS-SYNC n/c
n/c
n/c
EPSI
EPSCLK
EPSO
EPSCSN
BOOTEN1
BOOTEN2
C1
X1 C2
C3
R1
CMX7032Q1/L9
RF1
RF2
2
3
4
5
6
7
8
9
10
11
12
1
RF1P
RF2P
CP1OUT
CP2OUT
ISET1
ISET2
RFVSS
RFVDD
RFVDD
CPVDD
(3.3V)
(2.5V)
RF1N
RF2N
RFVSS
RFVSS
RFVSS
CPVDD 13
14
15
16
17 18 19 20 21 22 23 24
C17 C18 C19
MOD1
MOD2
AVSS
SpareN
RX1N
SLOTCLK
SYSCLK1
SpareFB
RX2FB
TXENA
RX2N
DVSS
RX1FB
C16
C14
C12
C9
C8
MOD2
Spare
RX1
RX2
MOD1
AVSS
AVSS
DVSS
AVSS
AVDD
AVSS AVSS AVSS
R3
R4
R10
R8
R9R7
R5
R6
+
C20 C21 C22
DVDD
DVSS DVSS DVSS
+
RFCLK
C23
C26
C28
C24
C25
C27
RFVDD
CPVDD
RFVSS
RFVSS
DVSS
RFVSS
RFVSS
DVSS
+
+
+
DAC3
DAC4
Figure 2 CMX7032 Recommended External Components
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ADCs
DACs
C-BUS
18 C7
DAC2
DAC1
VDEC
VDEC
ADC2
RSSI2
AVDD
DVDD
DVDD
AVDD
XTAL/CLK
ADC1
RSSI1
IRQN
XTALN
DVSS
DVSS
AVSS AVSS
DVSS
DVSS
DVSS
DVSS
AVSS
DVDD
SYSCLK2
VBIAS
CDATA (COMMAND DATA)
SCLK (SERIAL CLOCK)
RDATA (REPLY DATA)
CSN
n/c
EPSI
EPSCLK
EPSO
EPSCSN
BOOTEN1
BOOTEN2
C1
X1 C2
C3
R1
CMX7042Q3/L4
1
2
3
4
5
6
7
8
9
10
11
12
13 14 15 16 17
C17 C18 C19
MOD1
MOD2
AVSS
SpareN
RX1N
CS-SYNC n/c
SLOTCLKOP
SLOTCLK
SYSCLK1
SpareFB
RX2FB
TXENA
RX2N
DVSS
RX1FB
C16
C14
C12
C9
C8
MOD2
MOD1
AVSS
AVSS
DVSS
AVSS
AVDD
AVSS AVSS AVSS
R3
R4
R10
R8
R9R7
R5
R6
+
C20 C21 C22
DVDD
DVSS DVSS DVSS
+
C24 C23
DVSS DVSS
+
DAC3
DAC4
Spare
RX1
RX2
Figure 3 CMX7042 Recommended External Components
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Table 2 Component Values
R1
100k
C1
18pF
C16
100pF
C23
10nF
R3
100k
C2
18pF
C17
10µF
C24
10µF
R4
100k
C3
10nF
C18
10nF
C25
10nF
R5
See note 2
C4
not fitted
C19
10nF
C26
10µF
R6
100k
C7
100nF
C20
10µF
C27
10nF
R7
See note 3
C8
100pF
C21
10nF
C28
10µF
R8
100k
C9
100pF
C22
10nF
R9
See note 4
C12
100pF
X1
9.6MHz
R10
100k
C14
100pF
See note 1
Resistors 5%, capacitors and inductors 20% unless otherwise stated.
Notes:
1. X1 can be a 9.6MHz crystal or a 19.2MHz external clock generator. The tracks between the crystal and the
device pins should be as short as possible to achieve maximum stability and best start up performance.
2. R5 should be selected to provide the desired dc gain (assuming C11 is not present) of the input, as follows:
GAINRX1N = 100k / R5
The gain should be such that the resultant output at the RX1FB pin is within the input signal range specified
in 8.1.3.
3. R7 should be selected to provide the desired dc gain (assuming C13 is not present) of the input as follows:
GAINRX2N = 100k / R7
The gain should be such that the resultant output at the RX2FB pin is within the input signal range specified
in 8.1.3.
4. R9 should be selected to provide the desired dc gain (assuming C15 is not present) of the input as follows:
GAINSpareN = 100k / R9
The gain should be such that the resultant output at the SpareFB pin is within the input signal range
specified in 8.1.3.
5. Care should be taken in connecting the output of the Limiter-Discriminator device to the Rx input pins of the
CMX7032. The format of the GMSK signal requires that the frequency response of the input circuits extends
to below 10Hz, however the variations in the incoming AIS signals from many different stations require that
the input must rapidly follow the changes in dc and signal levels without de-grading the signal seen at the Rx
input pins.
6. A single 10µF electrolytic capacitor (C24, fitted as shown) may be used for smoothing the power supply to
both VDEC pins, providing they are connected together on the pcb with an adequate width power supply
trace. Alternatively, separate smoothing capacitors should be connected to each VDEC pin. High frequency
decoupling capacitors (C3 and C23) must always be fitted as close as possible to both VDEC pins.
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Figure 5 CMX7042 Power Supply Connections and De-coupling
Component Values as per Table 2.
Notes:
1. It is important to protect the analogue pins from extraneous inband noise and to minimise the impedance
between the CMX7032 and the supply and bias de-coupling capacitors. The supply decoupling capacitors
should be as close as possible to the CMX7032. It is therefore recommended that the printed circuit board
is laid out with separate ground planes for the AVSS, RFVSS and DVSS supplies in the area of the
CMX7032, with provision to make links between them, close to the CMX7032. Use of a multi-layer printed
circuit board will facilitate the provision of ground planes on separate layers.
2. The central metal pad (which is exposed on Q1 and Q3 packages only) may be electrically unconnected or,
alternatively, may be connected to Analogue Ground (AVSS). No other electrical connection is permitted.
3. VBIAS is used as an internal reference for detecting and generating the various analogue signals. It must
be carefully decoupled to ensure its integrity so, apart from the decoupling capacitor shown, no other loads
should be connected. If VBIAS needs to be used to set the discriminator mid-point reference, it must be
buffered with an external high input impedance buffer.
4. The 2.5V VDEC output can be used to supply the 2.5V RFVDD, to remove the need for an external 2.5V
regulated supply. VDEC can be directly connected to RFVDD.
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6 General Description
6.1 Overview
Tx Modem Functions
AIS 25kHz channel (GMSK, 9600bps, 2.4kHz deviation, BT = 0.4)
AIS Burst mode with full AIS frame formatting (HDLC-type)
o Bit stuffing
o NRZI coding
o Training sequence and start/stop flag insertion
o CRC generation
AIS Raw mode (for greater flexibility)
o Supports arbitrary data streams for user-defined protocols
Full support for the AIS Class B carrier-sensing channel access scheme (CSTDMA)
Full support for the AIS Class B Self-organising TDMA access scheme
160 byte (equivalent to 5 AIS slots) Tx data buffer
Flexible Tx Interface
o Two-point modulation outputs, with independent gain and polarity controls
o I/Q modulation outputs, for use with an I/Q upconverter
CS-SYNC output to facilitate IEC 62287-1 testing
Rx Modem Functions
Configurable modulation format:
o AIS 25kHz channel (GMSK, 9600bps, 2.4kHz deviation, BT = 0.4)
o DSC (de-emphasised FSK, 1200bps)
Simultaneous reception of two AIS channels, or one AIS and one DSC channel
AIS Burst mode with full AIS frame formatting (HDLC-type)
o Frame sync recognition
o Bit de-stuffing
o NRZI decoding
o Training sequence and start/stop flag detection
o CRC checking
AIS Raw mode (for greater flexibility)
o Supports arbitrary data streams for user-defined protocols
DSC reception
o Raw mode
o Formatted mode
Four 160-byte Rx data buffers can automatically store up to four 5-slot AIS bursts (2 per Rx
channel)
Rx signal input gain and polarity controls
Time-of-arrival reporting assists with timekeeping in the absence of GPS
Option to report messages with CRC errors
100 - 600 MHz RF Synthesisers (CMX7032 only)
Two Integer-N synthesisers
Flexible design minimises reference spurs for low phase noise results
Charge pump
o High/low soft selectable current setting to speed large frequency channel changes
o Nominal current user defined by external resistor value
Lock detect
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Analog I/O Functions
Auxiliary ADC system
o Two 10-bit successive approximation ADCs with integrated sample and hold
o One AuxADC is dedicated to RSSI measurement in a user defined window, the other is
available for general use
Ramping auxiliary DAC
o DAC sequences through a user-configured sequence of DAC output values to develop a
specific rising/falling DAC output signal. This is useful for ramping an RF PA, and can be
configured to happen automatically at the start and end of a burst.
o Can operate as a general purpose DAC, if desired
Three general purpose auxiliary DACs
System Functions
All internal subsystems are controlled via a single serial host interface to reduce host µC pin count
and simplify external host driver complexity.
Transaction oriented command/response logical host interface executes tasks supporting normal
operation, device configuration, and functions to assist manufacturing calibration trimming of
external circuits.
Internal system clock derived from RF synthesiser reference oscillator and eliminates the need for
additional XTAL or baseband clock oscillator.
User clock synthesisers generate two clocks for external use and eliminates an external clock
synthesiser when needed to support peripheral devices.
User selected method for loading a Function Image™ - either from the host µC via C-BUS or from
an external serial memory.
Integrated 2.5V regulator can develop 2.5V from required 3.3V supply.
Powersave facilities minimize total system power.
6.2 AIS system formats
The AIS system uses two basic channel access mechanisms: Self Organising Time Division Multiple
Access (SOTDMA) and Carrier-Sensing Time Division Multiple Access (CSTDMA). The CMX7032 and
CMX7042 are compatible with both systems and offer additional features which simplify the
implementation of CSTDMA. The SOTDMA system is detailed in ITU-R M.1371-1 and IEC 61993-2 while
the CSTDMA is detailed in IEC 62287.
The CSTDMA system is used in the implementation of the Class B-CS AIS. This requires the receiver to
monitor the first part of a slot for an existing AIS transmission from another station before deciding to use
the slot for its own transmission or aborting and selecting a different slot.
The SOTDMA system is used in the Class A and Base Station AIS as well as the Class B-SOTDMA AIS
standard.
The CMX7032 and CMX7042 are particularly well suited to the Aids to Navigation applications where
power consumption must be minimised.
The relevant International standards are:
[0] ITU-R M.1371-4
[1] IEC 61993-2 Class A
[2] IEC 62287-1 Class B CSTDMA
[3] IEC 62287-2 Class B SOTDMA
[4] IEC 62320-1 Base Station
[5] IEC 62320-2 Aids to Navigation
[6] IEC 61097-14 AIS-SART
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7 Detailed Descriptions
7.1 Clock Source
The CMX7032/CMX7042 can be used with either a 9.6MHz xtal or a 19.2MHz oscillator. The RF clock
(RFCLK) should also be derived from this source to avoid the generation of unwanted spurious signals.
7.2 Host Interface
This section provides a general description of the C-BUS serial interface protocol used to transfer data,
control and status information between the CMX7032/CMX7042 and its host. On the CMX7032 only, the
C-BUS serial interface must be enabled by permanently connecting CBUSMODE (pin 57) to digital ground
(DVSS).
C-BUS is a serial interface, similar to SPI, that uses a simple transaction-oriented command/response
protocol with addressing to access specific registers within the CMX7032. Each C-BUS transaction
consists of a single Register Address/Command byte (A/C byte) sent from the µC which may be followed
by one or more data byte(s) sent from the µC to be written into one of the CMX7032’s Write Only registers,
or one or more data byte(s) read out from one of the CMX7032’s Read Only registers, as illustrated in
Figure 6.
Data sent from the µC on the CDATA line is clocked into the CMX7032/CMX7042 on the rising edge of the
SCLK input. RDATA sent from the CMX7032/CMX7042 to the µC is valid when the SCLK is high. The
CSN line must be held low during a data transfer and kept high between transfers. The C-BUS interface is
compatible with most common µC serial interfaces and may also be easily implemented with general
purpose µC I/O pins controlled by a simple software routine.
The number of data bytes following an A/C byte is dependent on the value of the A/C byte. The most
significant bit of the address or data is sent first. For detailed timings see section 8.2.
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C-BUS Write:
See Note 1
See Note 2
CSN
SCLK
CDATA
7
6
5
4
3
2
1
0
7
6
…
0
7
…
0
MSB
LSB
MSB
LSB
MSB
LSB
Address / Command byte
Upper 8 bits
Lower 8 bits
RDATA
High Z state
C-BUS Read:
See Note 2
CSN
SCLK
CDATA
7
6
5
4
3
2
1
0
MSB
LSB
Address byte
Upper 8 bits
Lower 8 bits
RDATA
7
6
…
0
7
…
0
High Z state
MSB
LSB
MSB
LSB
Data value unimportant
Repeated cycles
Either logic level valid
Figure 6 C-BUS Transactions
Notes:
1. For Command byte transfers only the first 8 bits are transferred.
2. For single byte data transfers only the first 8 bits of the data are transferred.
3. The CDATA and RDATA lines are never active at the same time. The Address byte determines the data
direction for each C-BUS transfer.
4. The SCLK input can be high or low at the start and end of each C-BUS transaction.
5. The gaps shown between each byte on the CDATA and RDATA lines in the above diagram are optional, the
host may insert gaps or concatenate the data as required.
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7.3 Function Image™ Load and Activation
The Function Image™ (FI) file, which defines the operational capabilities of the device, may be obtained
from the CML Technical Portal, following registration. This is in the form of a 'C' header file which can be
included into the host controller software or programmed into an external serial memory. The maximum
possible size of Function ImageTM is 46kbytes, although a typical FI will be less than this. Note that the
BOOTEN pins are only read at power-on or following a C-BUS General Reset and must remain stable
throughout the FI loading process. Once the FI load has completed, the BOOTEN pins are ignored by the
CMX7032/CMX7042 until the next power-up or C-BUS General Reset.
The BOOTEN pins are both fitted with internal low-current pull down devices.
For C-BUS load operation, both pins should be pulled high by connecting them to VDD either directly or via
a 220kΩ resistor (see Table 3).
For serial memory load, only BOOTEN1 needs to be pulled high in a similar manner, however, if it is
required to program the serial memory in-situ from the host, either a jumper to VDD or a link to a host I/O
pin should be provided to pull BOOTEN2 high when required (see Table 3).
Once the FI has been loaded, the CMX7032/CMX7042 performs these actions:
(1) the product identification code ($7032 or $7042) is reported in C-BUS register $C5
(2) the FI version code is reported in C-BUS register $C9
(3) the two 32-bit FI checksums are reported in C-BUS register pairs $A9, $AA and $B8, $B9
(4) the device waits for the host to load the 32-bit Device Activation Code to C-BUS register $C8
(5) once activated, the device initialises fully, enters idle mode and becomes ready for use, and the
Activation Register Ready (ACT) flag (bit 0 of the Status register) will be set.
The checksums should be verified against the published values to ensure that the FI has loaded correctly.
Once the FI has been activated, the checksum, product identification and version code registers are
cleared and these values are no longer available. If an invalid activation code is loaded, the device will
report the value $DEAD in register $A9 and become unresponsive to all further host commands (including
General Reset). A power-on reset is required to recover from this state.
Both the Device Activation Code and the checksum values are available from the CML Technical Portal.
Table 3 BOOTEN Pin States
BOOTEN2
BOOTEN1
C-BUS Host load
1
1
reserved
1
0
Serial Memory load
0
1
No FI load
0
0
Note: Following a General Reset, reloading of the Function Image is strongly recommended.
7.3.1 FI Loading from Host Controller
The FI can be included into the host controller software build and downloaded into the
CMX7032/CMX7042 at power-up over the C-BUS interface. The BOOTEN pins must be set to the C-BUS
host load configuration, the CMX7032/CMX7042 powered up, wait for the ACT flag to be set (Status
register $C6 bit 0), then the data can then be sent directly over the C-BUS to the CMX7032/CMX7042.
Each time the device is powered up its Function Image™ must first be loaded and then activated. These
two steps assign internal device resources and determine all device features. The device does not
operate until the Function Image™ is loaded and activated.
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BOOTEN 2 = 1
BOOTEN 1 = 1
Power-up or
write General Reset to CMX7032/CMX7042
Poll $C6 until b0 = 1 (ACT flag set)
Configure ACT flag interrupt, if required
Write $0001 to $C8
Write Start Block 1 Address (DB1_ptr) to $B6
Write Block 1 Length (DB1_len) to $B7
Wait for ACT flag to go high or interrupt
Write next data word to $C8
Wait for ACT flag to go high or interrupt
Write Start Block 2 Address (DB2_ptr) to $B6
Write Block 2 Length (DB2_len) to $B7
Write $0001 to $C8
Wait for ACT flag to go high or interrupt
Wait for ACT flag to go high or interrupt
Write next data word to $C8
Write Start Block 3 Address (ACTIVATE_ptr) to $B6
Write Block 3 Length (ACTIVATE_len) to $B7
Write $0001 to $C8
Wait for ACT flag to go high or interrupt
Send Activation Code hi to $C8
Read and verify checksum values in register pair:
$A9 and $AA, $B8 and $B9
Send Activation Code lo to $C8
Wait for ACT flag to go high or interrupt
Wait for ACT flag to go high or interrupt
BOOTEN1 and BOOTEN2 may be
changed from this point on, if required
CMX7032/CMX7042 is now ready for use
BOOTEN1
BOOTEN2
VDD
Figure 7 FI Loading from Host
The download time is limited by the clock frequency of the C-BUS, with a 5MHz SCLK, it should take less
than 500ms to complete.
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7.3.2 FI Loading from Serial Memory
The FI must be converted into a format for the serial memory programmer (normally Intel Hex) and loaded
into the serial memory either by the host or an external programmer. The CMX7032/CMX7042 needs to
have the BOOTEN pins set to serial memory load, and then on power-on, or following a C-BUS General
Reset, the CMX7032/CMX7042 will automatically load the data from the serial memory without
intervention from the host controller.
BOOTEN 2 = 0
BOOTEN 1 = 1
Power-up or write General Reset to
CMX7032/CMX7042
Poll $C6 until b0 = 1 (ACT flag set)
Configure ACT flag interrupt if required
Send Activation Code hi to $C8
Read and verify checksum values in register pair:
$A9 and $AA, $B8 and $B9
Send Activation Code lo to $C8
Wait for ACT flag to go high or interrupt
Wait for ACT flag to go high or interrupt
BOOTEN1 and BOOTEN2 may be
changed from this point on, if required
CMX7032/CMX7042 is now ready for use
BOOTEN1
BOOTEN2
Jumper for
programming
serial memory
(if required)
Figure 8 FI Loading from Serial Memory
The CMX7032/CMX7042 has been designed to function with Atmel AT25HP512 serial EEPROM and the
ATF512 flash EEPROM devices
2
, however other manufacturers’ parts may also be suitable. The time
taken to load the FI is dependant on the XTAL/CLK source frequency, but should be less than 500ms.
2
Note that these two memory devices have slightly different addressing schemes. FI-1.2 for the
CMX7032/CMX7042 is compatible with both schemes.
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7.4 System Description and Tasks
This section describes the operation of main sections of the CMX7032/CMX7042 and the task-oriented
logical interface provided to the external host device.
7.4.1 Signal Routing
The CMX7032/CMX7042 provides processing capability for two simultaneous receive channels (either two
AIS or one AIS and one DSC) or one Tx channel (AIS).
The inputs to the two receiver channels are nominally allocated to the RX1N and RX2N pins of the device,
however they can be re-allocated by the user by use of the Input Signal Routing C-BUS register, $B1. The
SpareN pin can also be used as an input to the receivers if required. By default the device will route RX1N
to Rx channel 1 and RX2N to Rx channel 2, which leaves the SpareN signal available to the ADC. All of
these inputs are configured around an inverting op-amp stage to facilitate gain and filtering adjustments. In
addition, the Rx channel inputs are equipped with programmable gain stages for further level adjustments
as required.
The Tx Modulation output signals may be configured to be suitable for two-point modulation circuits or
alternatively an I/Q upconverter. Signal levels on both output pins, MOD1 and MOD2, can be set to within
0.2dB using a Configuration Mode task.
7.4.2 Operating Modes
The CMX7032/CMX7042 operates in either:
o Configuration mode.
o Normal mode.
Configuration mode is used to set up various operating parameters of the CMX7032/CMX7042
subsystems, e.g. Transmit format, timing parameters etc. following a power-up or reset. The modem
section is disabled when the device is in Configuration mode. Configuration mode uses dedicated tasks
that are not valid whilst in Normal mode.
Normal mode is used when actively running the CMX7032/CMX7042 modem and other subsystems.
Normal mode uses dedicated tasks that are not valid whilst in Configuration mode.
“Enter Config Mode” (ECM) is a Normal mode task that switches the device from Normal to Configuration
mode. “Exit Config Mode” (EXIT_CONFIG) is a Configuration mode task that switches the device from
Configuration to Normal mode.
7.4.3 Modem and Data Units
The CMX7032/CMX7042 is logically divided into two main units which can accept and perform tasks
separately:
o Modem Unit
o Data Unit
The Modem Unit is primarily responsible for processing Tx data from the internal Tx data buffer,
presenting it on the MOD1 and MOD2 pins, processing the Rx input signals to recover the Rx data they
represent and storing that data in the internal Rx data buffers.
The Data Unit is primarily responsible for transferring data between the internal data buffers or
subsystems and the C-BUS registers, from where they can be accessed by the host µC.
When the device is in Normal mode, the Command register, $C8, is a 16 bit C-BUS write register that
contains task fields for both Data and Modem units. A task is invoked by writing its code into the Data
Task or Modem Task fields. A single C-BUS write transaction will change all Command register fields.
Often, the host will only want to issue either a Data or Modem task, in which case it should ensure that the
other task field is set to all zeroes, corresponding to a null/idle task. Sometimes it is useful to issue Data
and Modem tasks simultaneously, in which case, the Data task will always be completed before the
Modem task is started.
Certain internal subsystems can be directly accessed and controlled via C-BUS transactions, without
issuing a specific task/command.
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7.4.4 Timing and Synchronisation
An AIS transponder must keep track of both the current AIS slot number and the position within the slot.
This is principally to ensure that transmissions occur at the right time, and that hardware is correctly
switched between Rx and Tx, but is also useful for scheduling when to take RSSI measurements, when
receivers can be powered down and when they should wake up again.
In an AIS Class A transponder, the clock is synchronised with a 1Hz tick from a GNSS (GPS) unit. In a
Class B transponder the clock may be synchronised to the GNSS tick, or may be synchronised to the
reception time of AIS bursts from a Class A transponder or Base Station. Note that the latter scheme
requires management by the host µC, which must determine which received bursts are qualified to be
used as a timing reference. Whichever of these methods is used by the transponder, the
CMX7032/CMX7042 requires a Slot Clock (SLOTCLK) input from the host µC. This should be a pulse at
least 50µs long, whose rising edge is aligned to the AIS Slot boundary. An edge is required at the start of
every AIS slot, hence the frequency of this signal is 37.5Hz.
The CMX7032/CMX7042 has several features to assist the host µC with timing, which are detailed below.
All of these features are based on the SLOTCLK signal, provided by the host to the CMX7032/CMX7042’s
SLOTCLK pin. All timings are defined as a number of 24kHz “ticks” referenced to the rising edge of the
SLOTCLK signal.
7.4.5 Time of Arrival Reporting
When the CMX7032/CMX7042 has received a burst as the result of an RXB1/2 (receive burst) task, the
time of arrival is presented as one of the first four words of the Data Block. This will give the time,
measured in 24kHz ticks, between the rising edge of the last SLOTCLK and the detection of the last bit of
the start flag of the burst (Tsync in ITU-R M.1371-3). The current Slot Number (as determined by the
internal slot counter) will also be returned in the Data Block. Note that the internal filters and signal
processing results in a delay of up to 20 ticks – this can be automatically removed by the use of the Config
Mode task, ToA compensate. For a received burst from a Class A Transmitter that is exactly aligned with
the SLOTCLK, the ToA indicated will be calculated as:
AIS data field
bits
ticks
Tx rise time
8
20
Preamble
24
60
Start flag
8
20
Internal delay
20
Total
120
Note that additional delays due to signal processing through external hardware may add to this value.
The internal slot counter increments on every rising edge of the SLOTCLK, or when then the internal tick
counter reaches 640. This is not subject to the internal filter delays. The internal tick counter is initialized
on every rising edge of SLOTCLK. In the absence of a SLOTCLK signal, it will free-run, based on the
internal 24kHz clock, modulo 640.The internal SLOTCLK is output as a pulse on the SLOTCLKOP pin .
7.4.6 Tx Timing
The CMX7032/CMX7042 can be configured to perform a sequence of events when a TXB or TDBS task
(transmit burst) is issued. The events are: start and end of modulation, ramping the RAMDAC up and
down, asserting and releasing a digital output pin (intended as a Tx Enable) and CSTDMA sensing. Each
of these can be configured to happen with specified delays from the rising edge of the SLOTCLK. The
timings are set up with the Config Mode task Tx_Sequence. See User Manual section 9.19.7 for details.
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PA Ramp &
Modulation
Time
SlotCLK
SlotCLK
Tx Timing
CSTDMA
Sensing
Tx Enable
Wait
Figure 9 Tx Burst Timing
If CSTDMA sensing has been enabled then the CMX7032/CMX7042 will measure the carrier level (RSSI)
on the selected channel during the window specified in the transmit timing table. If the user-specified
threshold is exceeded then the subsequent events (RAMDAC, Tx Enable and modulation) will be
cancelled. The threshold is set using the CS_Threshold register, $C2. See User Manual section 9.16 for
details. The device will output a pulse on the CS-SYNC pin, co-incident with the SLOTCLK, when it intends
to attempt a transmission. This is provided to simplify testing under IEC 62287-1 section 12.2.1. The signal
will return to its inactive state when the TxDone task is executed, either as a result of a CS abort or if the
transmission succeeded.
7.4.7 Rx Timing
The CMX7032/CMX7042 has a powersaving mode, where it spends most of its time ‘asleep’, but ‘wakes
up’ at the start of each AIS slot and receives for long enough to determine whether a burst is present or
not. If no burst is received the CMX7032/CMX7042 will make a pair of RSSI measurements and then go
back to sleep. This power saving operation can be turned on and off using the Sleep Mode En bit in the
Mode register, $C1. The CMX7032/CMX7042 will still respond to C-BUS accesses when ‘asleep’ but the
latency between a task being issued and completed may be longer than normal.
The times to perform RSSI measurements, go to sleep, and wake up are configured by the host, and all
times are referenced to the SLOTCLK signal. The host should ensure that these timings result in the
CMX7032/CMX7042 being awake in time to sample the next SLOTCLK signal. The timings are set up
using the Sleep_Timing Config task. See User Manual section 9.19.8 for details.
If Sleep mode is not enabled, then the demodulator will run continuously and update the Rx Data buffer
whenever valid data is received.
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Received Burst
SLOTCLK
SLOTCLK
Rx Timing
RSSI1 RSSI2
Measurement
Training
sequence
search
Time
Sleep (if no burst received)
Wake up in time for
next slotclock
Wait
Figure 10 Rx Burst Timing
7.4.8 CSTDMA Threshold Measurement
The CMX7032/CMX7042 provides support for the CSTDMA mode of operation by measuring the signal
level at the start of a slot period and aborting the transmission if a level over a user defined threshold is
found. This fact is reported to the host in Status2 C-BUS register $C5.
The CSTDMA threshold measurement window is setup by the Tx_Sequence Config task using timing
values based on the number of 24kHz “tick” increments from the rising edge of the SLOTCLK pulse.
During this period (if Tx_Status and CS-EN are both “active”) the CMX7032/CMX7042 will measure the
RSSI level of the appropriate channel (set in C-BUS Mode register $C1):
1. sample RSSI at 48k samples/sec
2. scale values to 0 - 127
3. apply the look-up table values
4. apply the CSTDMA_gain value
5. accumulate values over the defined period
6. compare the value with the value in the C-BUS CS-Threshold register $C2 and abort the
transmission if it is exceeded.
Note that the same lookup table is used for both CSTDMA Threshold measurement as the RSSI
measurement.
7.4.9 RSSI Measurement
RSSI can not be determined directly from the baseband signal output of a limiter-discriminator device so
the CMX7032/CMX7042 has two dedicated inputs (one for each Rx channel) for separate external
analogue RSSI signals. Suitable outputs are available on many limiter-discriminator ICs, e.g. Philips
SA605. The ADCs sample the signals during a user-defined window and apply an averaging algorithm and
present the results in C-BUS registers $BA and $BB.
The RSSI measurement windows are set up using the RSSI_Window config task using timing values
based on the number of 24kHz “tick” increments from the rising edge of the SLOTCLK plulse. During this
period (if Tx_Status is not “active”) the device will:
1. sample RSSI at 48k samples/sec
2. scale values to 0 -127
3. apply the look-up table values
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4. apply the RSSI_gain value
5. accumulate values over the defined period
6. output values to C-BUS registers
Note that the RSSI measurements on each RF channel run consecutively and that the C-BUS registers
are updated at the end of the RSSI_2 measurement window.
7.4.10 RSSI Calibration
The RSSI signal should be approximately logarithmically scaled (i.e. a nearly linear relationship between
voltage and signal strength in dBs). In order to reduce the impact of noise, the CMX7032/CMX7042
averages over several samples, but to give a meaningful average, the samples must first be anti-logged.
In order to correct any non-linearities in the RSSI response, and to set an offset for the anti-logging, the
host must supply calibration data.
The calibration data is a 128-entry table. The entries correspond to equally-spaced voltages from 0V to
3.3V (nominal – see 8.1.3) applied to the RSSI inputs. To set up the table the host uses the RSSI_Lookup
config task. See section 7.8 for details. The default values are shown in User Manual section 9.19.3.
7.4.11 ADCs
The first ADC is dedicated to RSSI measurements at times specified by the host µC, see Section 7.4.8
and User Manual 9.19.4. The second ADC is available for user functions. The ADC runs continuously, the
input selected by the ADC Input Select bits in the C-BUS Mode register, $C1 and the results of the
conversion are presented in ADC Data C-BUS register $C9. This register also includes a bit field to
indicate which input was selected when this conversion was executed. The ADC input can be routed to
either of the RXnN signals, the SpareN input, the RSSI inputs or the ADC inputs under host control. In
normal operation it is expected to be routed to one of the ADC Inputs.
7.4.12 DACs
The four DACs can be updated in any combination using the DAC_Write data task. See User Manual 9.19
In addition, DAC1 can be configured as a RAMDAC to output a series of values as part of the transmit
timing sequence. The values and the rate at which they change are set-up using a Config mode task.
7.4.13 Interrupt Operation
The CMX7032/CMX7042 will issue an interrupt on the IRQN line when the IRQ bit (bit 15) of the Status
register and the IRQ Mask bit (bit 15) are both set to 1. User Manual section 9.21 describes the situations
which cause the IRQ bit to change from a 0 to a 1. The IRQN pin is an open collector output that requires
an external pull-up resistor.
7.4.14 Deep Sleep Mode
“Deep Sleep” mode (entered through Configuration mode) puts the device into static state where all signal
processing and clocks are stopped and only the C-BUS remains active. In this mode, the IDD drops to the
lowest level, as specified in section 8.1.3, and is thus suitable for use on Aids to Navigation, or other
implementations where it is feasible for the host µC to switch off the CMX7032/CMX7042 at known times.
See User Manual section 9.19.11.
7.5 Operation of Tasks
This section describes modem and data tasks. Understanding their operation requires knowledge of the
internal buffering of the CMX7032.
Tx and Rx data is double buffered. Each Tx or Rx channel has a Data Buffer. The host µC accesses the
C-BUS registers and the modulator/demodulator directly accesses the Data Buffers. Tasks transfer data
between the buffers and the C-BUS registers.
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7.5.1 Tx Task Operation
Typical stages of Tx task operation are depicted in Figure 11 and occur as follows:
1. The host writes up to 4 words of data for transmission into the Write Data C-BUS registers.
2. The host writes the Command register, specifying a data task. This results in transfer of the data
from the Write Data registers into the Tx Data Buffer.
3. Steps 1 and 2 can be repeated to load the Tx Data Buffer with a large block of data.
4. A Modem task can then be used to instruct the Tx Modulator to transmit the data in the Data
Buffer. This causes the content of the Tx Data Buffer to be coded and CRC’d (if in burst mode)
and transmitted to the MOD1 and MOD2 output pins.
5. Once the system is up and running any modem task may potentially take some time to execute as
it may have to wait for the previous task to complete.
B
7
A
8
A
7
B
6
Tx Data Buffer
(88 words) Modulator
Command Register
Data Task Modem Task
Command Reg Free
Data Task Complete TBFree TxState
TxDone
C-Bus
registers
Figure 11 Tx Task Operation
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7.5.2 Rx Task Operation
Typical stages of Rx task operation are depicted in Figure 12 and occur as follows:
1. A Modem task instructs the CMX7032/CMX7042 to transfer data from the Rx1/2 Modem to the
Rx1/2 Data Buffer.
2. The host writes to the Command register, specifying a Data task. This results in transfer of up to
4 words from the Rx1/2 Data Buffer into the Read Data C-BUS registers, from where it can be
read by the host µC.
3. Steps 2 can be repeated (with host µC reads of the Read Data registers) to transfer a large block
of data from the Rx1/2 Data Buffer to the host µC.
4. Once the system is up and running any modem task may take some time to execute, as it will
need to wait for the data to be available from the modem.
Command Register
Data Task Modem Task
Command Reg Free
Data Task Complete
R1BRDY
RxState1/2
R1BOVF
Rx Data
Buffer
(88 words)
demodulator
Rx Data
Buffer
(88 words)
sw sw
Rx Data
Buffer
(88 words)
demodulator
Rx Data
Buffer
(88 words)
sw sw
R2BRDY
R2BOVF
B
9
A
A
A
9
B
8
C-Bus
registers
select
Figure 12 Rx Task Operation
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7.5.3 Registers and Buffers for Tx/Rx Tasks
Command register: contains Data and Modem task fields as described above.
Status register: contains bits that indicate when tasks are complete, which can interrupt the host:
o Command Reg Free
o TBFREE
o R1BRDY
o R2BRDY
o TxDONE
o Rx1BOVF
o Rx2BOVF
o Config Task Complete
o Data Task Complete
Interrupt Mask: Host write register to specify which status bit can cause an interrupt.
Write Data registers 0-3: Contain data written from host µC to transmit via the Tx Modulator.
Read Data registers 0-3: Contain data received from Rx Demod for host µC to read.
Tx Data Buffer: The Tx Data is double buffered, which allows the host µC to write to the Tx Data
Buffer while the modulator is simultaneously transmitting data it reads from the Tx Modem Buffer.
Each buffer is capable of holding one full (5-slot) AIS message.
Rx1/2 Data Buffer: The demodulator writes data directly into these internal buffers. There are two
buffers per channel which are used alternately every time a new burst is detected. This allows the
host µC to read from one buffer while reception continues to fill the other. Each buffer is capable
of holding a full (5-slot) AIS message.
7.5.4 Write Data Registers
An array of four, 16 bit, C-BUS write registers form the Write Data C-BUS registers.
The device reads and acts upon the content of these data write registers as instructed by the Data Task
bits of the Command register while in transmit mode. Generally, they may be written at any time by the
host µC with no effect on internal device operation. When a “Data task” is issued the Data registers will be
read by the device and so should not be modified by the host µC until the Data Task complete bit is set in
the Status register.
Data tasks access the registers as a number of words (1 to 4) or as a number of bits (1 to 16 in $A7),
however if a bit-format Data Task is used it must be the final data task issued in a multi-data transfer from
the host. The next data task issued should be a DataWordResetN_Tx or DataBitResetN_Tx to re-initialise
the internal data buffer pointers (a bit-format task is usually used as the last transfer of a data block that is
not a complete number of words in length).
Word-format:
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $A7
Data write from host µC to device word 1(MSB sent first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $A8
Data write from host µC to device word 2(MSB sent first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $B6
Data write from host µC to device word 3(MSB sent first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $B7
Data write from host µC to device word 4(MSB sent first)
Bit-format:
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $A7
Data write from host µC to device bits 0-15, (bit 15 transmitted first)
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7.5.5 Read Data Registers
An array of four, 16 bit, C-BUS read registers form the Read Data C-BUS registers.
The device writes into these registers as instructed by the Data Task bits of the Command register while in
receive mode. The host µC can read these registers at any time except while a data task is in progress, in
which case the host µC should wait until the Data task complete bit is set in the Status register.
Data tasks access the registers as a number of words (1 to 4) or as a number of bits (1 to 16 in $A7),
however if a bit-format Data task is used it must be the final data task issued in a multi-data transfer to the
host. The next data task issued should be a DataWordResetN_Tx1/2 or DataBitResetN_Tx1/2 to re-
initialise the internal data buffer pointers (a bit-format task is usually used as the last transfer of a data
block that is not a complete number of words in length).
Word-format:
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $A9
Data read from device to host µC word 1 (MSB Rx first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $AA
Data read from device to host µC word 2 (MSB Rx first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $B8
Data read from device to host µC word 3 (MSB Rx first)
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $B9
Data read from device to host µC word 4 (MSB Rx first)
Bit-format:
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Register $A9
Data read from device to host µC bits 0-15, (bit 15 received first)
7.5.6 Data Tasks
Data tasks are used to:
Load data from the Write Data registers into Data Buffers while in normal or configuration modes.
Load data from Data Buffers into the Read Data registers while in normal mode.
Load data from the Data Buffers to the DACs.
Read, write or operate subsystems by passing data using the Write Data and Read Data registers.
Table 4 Data Tasks
Name
Description
NULL
Null system task – takes no action.
DataWordReadN_Rx1
Copy N words (1 to 4) from Rx1 data buffer to C-BUS Read Data registers.
Increment Rx1 data buffer pointer.
DataWordReadN_Rx2
Copy N words (1 to 4) from Rx2 data buffer to C-BUS Read Data registers.
Increment Rx2 data buffer pointer.
DataWordWriteN_Tx
Copy N words (1 to 4) from Write Data registers to Tx data buffer.
Increment data buffer pointer.
DataWordResetN_Rx1
Reset Rx1 data buffer pointer to the top.
Copy N words (1 to 4) from Rx1 data buffer to Read Data registers.
Increment data buffer pointer.
DataWordResetN_Rx2
Reset Rx2 data buffer pointer.
Copy N words (1 to 4) from Rx2 data buffer to Read Data registers.
Increment data buffer pointer.
DataWordResetN_Tx
Reset Tx data buffer pointer.
Copy N words (1 to 4) from Write Data registers to Tx data buffer.
Increment the data buffer pointer.
DataBitReadN_Rx1
Copy N bits (1 to 15) from Rx1 data buffer to Read Data register 0.
Increment the data buffer pointer.
DataBitReadN_Rx2
Copy N bits (1 to 15) from Rx2 data buffer to Read Data register 0.
Increment data buffer pointer.
DataBitWriteN_Tx
Copy N bits (1 to 15) from Write Data register 0 to Tx data buffer.
Increment data buffer pointer.
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DataBitResetN_Rx1
Reset Rx1 data buffer pointer
Copy N bits (1 to 15) from Rx1 data buffer to Read Data register 0
Increment the data buffer pointer
DataBitResetN_Rx2
Reset Rx2 data buffer pointer
Copy N bits (1 to 15) from Rx1 data buffer to Read Data register 0
Increment data buffer pointer
DataBitResetN_Tx
Reset Tx data buffer pointer
Copy N bits (1 to 15) from Write Data register 0 to Txdata buffer
Increment data buffer pointer
DAC_Write
Interprets each of the first 1 to 4 words in the Write Data registers as a write command for the
Auxiliary DACs
7.5.7 Modem Tasks and Codes
Modem tasks transmit data on the MOD1 and MOD2 output pins or receive and recover data from the
RXnN pins. Modem tasks also coordinate data transfer between the Data Buffers and their respective
Modems.
Note that for receive tasks a 1 or 2 at the end of the task name refers to the Rx channel which is being
addressed.
Table 5 Modem Tasks
Name
Description
NULL
No command – takes no action
AbortRx1
Abort the ongoing modem task on Rx1, Rx2 or Tx
AbortRx2
AbortTx
ECM
Enter Configuration mode
Rx Tasks
Rx Raw bit = 0
Rx Raw bit = 1
RXB1
Rx Burst: Wait for a training sequence, then
demodulate, decode and store the burst
RXB2
RXR1
Demodulate and store N words. N is
defined by Rx data count register
RXR2
Tx Tasks
Tx Raw bit = 0
Tx Raw bit = 1
TXB
Code and transmit AIS message using contents
of data buffer. Start on next SLOTCLK
TDBS
Transmit contents of data buffer. Start on
next SLOTCLK
TDB
Transmit N data bits from the Tx mod
buffer. Start as soon as modulator is free
PRBS
Transmit pseudorandom bit sequence
TRW
Repeatedly transmit one word
HCT
Hardware Control
7.6 Transmission format
The CMX7032/CMX7042 is capable of transmitting AIS data in either raw mode or burst mode. AIS Carrier
Sensing (CSTDMA) for Class B systems is supported.
In AIS raw mode, data is passed directly from the Tx Data Buffer to the GMSK modulator, so the µC will be
responsible for sending any necessary training sequences and performing HDLC processing and NRZI
coding.
In AIS burst mode, the CMX7032/CMX7042 uses an internal message buffer to assemble an entire
message (up to 5 slots) to which it automatically adds the training sequence, start/stop flags, CRC, bit
stuffing and NRZI coding prior to transmission.
After setting up the appropriate registers, transmission is initiated by issuing a Tx Burst or Tx Raw task.
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7.6.1 Transmit Tasks
AbortTx:
This causes the current task on the Tx channel to abort. It also clears the Tx modem buffer.
TXB: Transmit AIS Burst
This task can only be executed if the Tx Raw bit (bit 5 in the command register) is cleared to 0.
This causes the CMX7032/CMX7042 to take the contents of the Tx Data buffer, apply AIS data
coding and transmit the resulting AIS message. The transmit sequence will start on the next
SLOTCLK edge.
The following four transmit tasks can only be executed if the Tx Raw bit is set to 1:
TDBS: Transmit Data Buffer on SLOTCLK
This causes the CMX7032/CMX7042 to transmit the data buffer contents using AIS modulation.
No data coding is applied, the Transmit Sequence will start on the next SLOTCLK edge.
TDB: Transmit Data Buffer
This causes the CMX7032/CMX7042 to transmit the data buffer contents using AIS modulation.
No data coding is applied. The data will be transmitted as the modulator is available (Transmit
Sequence is ignored).
PRBS: Transmit pseudorandom bit sequence
This task causes the CMX7032/CMX7042 to transmit an internally generated pseudorandom bit
sequence. The sequence is 511 bits in length, but will repeat indefinitely until aborted using the
AbortTx task, (Transmit Sequence is ignored).
TRW: Transmit Repeated Word
This task causes the CMX7032/CMX7042 to repeatedly transmit the first word currently in the data
buffer. Transmission will start immediately and will continue until an Abort Tx task is issued,
(Transmit Sequence is ignored).
HCT: Hardware Control Task
Allows manual control of ancillary hardware functions.
7.6.2 AIS Burst Mode Transmit
In AIS burst mode, the CMX7032/CMX7042 responds to a TXB task by performing bit stuffing, NRZI
encoding and the addition of training sequence, start/stop flags and CRC checksum as required by AIS.
Note: in AIS burst mode, the data words are automatically transmitted least significant bit first as required
by the AIS specification.
A number of error conditions are checked for during AIS burst mode transmit, each of which causes
transmission to be aborted and a Tx Done interrupt to be generated. The associated Tx states are:
Tx aborted, message too long:
This occurs if the internal message buffer is not big enough for the HDLC coded data (should not
happen in normal operation, as the message buffer is big enough for a 5-slot message). This condition
requires the µC to issue a AbortTx task.
Tx aborted, carrier sensed:
This occurs if the CSTDMA mechanism is enabled and the CS measurement has exceeded the CS
Threshold. The data is retained so that it can be re-transmitted in a subsequent slot (by issuing
another TXB task) should the host request it. The slot selection should follow the rules given in the
relevant international standard.
Tx aborted, buffer not ready:
This occurs in burst mode if the internal data coding has not completed before the timing_start value
expires.
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7.6.3 Transmit Example
The following detailed example describes the process of loading and transmitting an AIS message in Burst
mode.
Table 6 AIS Burst Transmit Example
Description
Cmd
Reg
Free
Data
Task
TBFREE
TxDONE
1.
The host should ensure that the TBFREE, Data Task and
CmdReg Free bits are set.
1
1
1
1
2.
The host loads the first N(typically 4) data words into the write
data registers.
1
1
1
1
3.
The host issues a DataWordResetN_Tx Data Task.
0
1
1
1
4.
Device reads the Command register & notes task types.
1
0
1
1
5.
Device carries out the data task by copying the N data words as
the first N data words of the data buffer.
1
1
1
1
6.
The steps above may be repeated (Using DataWordWriteN_Tx
tasks) to load many words until the data buffer contains enough
data to carry out the desired modem task.
7.
The host writes a TXB task to the Command register to start the
Tx process.
0
1
1
1
8.
Device reads the Command register.
1
1
0
1
9.
Device codes the data. Tx state changes from Idle to Tx Pending
1
1
1
0
10.
When the transmit point arrives (SLOTCLK), the Tx State changes
to Tx in progress and the TxSequence is activated.
11.
The Tx Modem Buffer will gradually empty as the Tx Modulator
continues transmitting.
1
1
1
1
12.
When the transmission ends the TxDone bit in the Status register
will be set, generating an interrupt if enabled. The host should
then check the Tx state bits in the Status2 register to see if
transmission was successful.
1
1
1
1
Note that if CSTDMA mode is active and a carrier is sensed in the selected channel at the beginning of the
requested transmit slot, the transmission is aborted (Tx State changes to Tx aborted, carrier sensed) – this
causes a TxDone interrupt to be generated, however the data in the Tx Data Buffer is retained, so the µC
can choose to issue an AbortTx task and clear the Tx Data Buffer, or reschedule the transmission in
another slot.
7.6.4 AIS Raw Mode Transmit
In AIS raw mode, transmit data is passed directly from the Tx Data Buffer to the GMSK modulator. The µC
must calculate the entire transmitted message including the training sequence, HDLC processing
(start/stop flags, bit stuffing, and CRC insertion) and NRZI coding. Note: In AIS raw mode, data words
written to the CMX7032/CMX7042 are transmitted most significant bit first. The AIS message structure,
however, requires each message byte to be output least significant bit first. The µC must therefore ensure
that during the process of HDLC processing and NRZI coding that the resulting data bytes are correctly
reversed.
7.6.5 Transmitter Timing Control
The CMX7032/CMX7042 can be configured to control the timing of transmission events whenever a Tx
Burst Modem task is executed. This includes the enabling of external RF circuits (e.g. synthesisers and
power amplifier), as well as the time at which internal data modulation begins. The flexibility of this timing
control allows the CMX7032/CMX7042 to be simply adapted to the characteristics of the RF transmit
circuits. The control of the external RF transmit circuits is performed using the TXENA pin and the DAC1
ramping function.
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B
RF
power
SLOTCLK
SLOTCLK
Time
100%
CS sense period
modulation
Figure 13 Typical AIS Transmission
A typical AIS transmission is shown in Figure 13. The CMX7032/CMX7042 starts timing relative to the
rising edge of SLOTCLK. At the end of a transmission, a sequence of “power-down” actions is performed
which are timed relative to the last message bit having been modulated, shown as point B in Figure 13. In
this way differences in message length due to bit stuffing are automatically accommodated.
The relative timings of the transmit sequence events are configured as a table of values that are loaded
into the CMX7032/CMX7042 using a Config Task operation (User Manual section 9.19.7) – this operation
must be performed before any transmissions are attempted. Typically, this will only need to be done once
as part of an initialization routine. All timings are measured in units of “ticks”, each of which lasts for
1/24000Hz ( 41.666µs).
The transmit sequence consists of two initial setting values followed by a number of different event types.
These are:
Initial delay from the SLOTCLK edge.
Initial state of the TXENA pin.
Changes to the external hardware, via the TXENA pin (typically used to turn the Tx on/off) and the
DAC1 ramp up/down.
Trigger for the start/end of the CSTDMA sensing period (if CSTDMA is enabled).
Timing triggers for the start and end of the data modulation.
A dummy event in case any of the above are not required in the application.
The transmit event sequence is programmed using a Config task, see User Manual section 9.19.7.
Table 7 Tx Sequence events
b3
b2
b1
b0
Event id
Description
0
0
0
0
dummy
Do nothing
0
0
0
1
CSTDMA_START
Defines the start of the CSTDMA sensing window
0
0
1
0
CSTDMA_END
Defines the end of the CSTDMA sensing window
0
0
1
1
Tx_en_hi
Pin TXENA is set high
0
1
0
0
RAMDAC_UP
AuxDAC1 will start executing a Ramp up
0
1
0
1
MODULATE_START
Defines the start of data modulation
0
1
1
0
MODULATE_END
Delay from the end of modulation (based on the last data bit loaded into
modem - includes a 20 tick delay for the internal filters)
0
1
1
1
RAMDAC_DOWN
AuxDAC1 will start executing a Ramp down
1
0
0
0
Tx_en_lo
Pin TXENA is set low
1
0
0
1
dummy
Do nothing
When calculating the MODULATE_START timing value, the delay through the CMX7032/CMX7042’s
internal transmit filters and any external components must be taken into account to ensure that data bits
appear on-air at the correct time (the filter delays are specified in section 8.1.4. The MODULATE_END
event has an in-built delay of 20 ticks to allow the last bit to make its way out of the transmit filter.
Allowance must be made for this built-in delay, as well as for the delay through any external components,
when calculating the timing of the transmit power down events.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 37 D/7032/42_FI1.2/12
A working example of how to set up a transmit event sequence is shown in Table 8 (the order of events
and delay timings shown are for illustrative purposes only):
Table 8 Example Tx Event Sequence Setup
Parameter
Event ID
delay
total
Explanation
CSTDMA_START
1
10
20
Insert 10 tick delay then start monitoring the chosen Rx
input for a signal which may cause an abort (if CSTDMA
enabled).
MODULATE_START
5
17
37
Insert 17 tick delay then start feeding data to the transmit
modulator and filters (this allows for the 20 tick storage
delay in the Tx filters so that modulated data appears at
the end of the RAMDAC ramp_up period – tick 57).
CSTDMA_END
2
10
47
Insert 10 tick delay then stop CSTDMA monitoring.
Tx_en_hi
3
0
47
Set TXENA line high (assuming not aborted)
RAMDAC_UP
4
3
50
Insert 3 tick delay then initiate the RAMDAC ramp-up (for
AIS, the transmitted signal will be carrier only at this
point)
At this point during a transmission the CMX7032/CMX7042 feeds the entire message to the transmit modulator bit-
by-bit. All subsequent transmit events are timed relative to the end of the last message bit, indicated by the
MODULATE_END event.
MODULATE_END
6
0
0
The 0 delay defines this reference point as the same as
the output of the final data bit to the RF circuits (“B” in
Figure 13).
RAMDAC_DOWN
7
0
0
Initiate the RAMDAC ramp-down immediately
Tx_en_lo
8
8
8
Insert 7 tick delay (to allow RAMDAC to fully ramp down)
then set the TXENA line low.
Notes:
1. It is essential that the CSTDMA, and MODULATE START events precede their associated END events,
otherwise undesirable results will be obtained.
2. MODULATE_START must appear in the first group of timed events (table entries 1–5), MODULATE_END must
appear in the final group (table entries 6-8).
3. It is feasible to place the RAMDAC_DOWN task before the MODULATE_END task if it is desired to continue
modulation during the Ramp down period.
Assuming that the timing_start value has been set to 10 (see User Manual section 9.19.7) and the RAMDAC is set
to its default values (312us), this sequence approximates to the Class B CSTDMA timing with ideal hardware
(RAMDAC starts 20bits / 50 ticks after SLOTCLK).
7.6.6 Modulation Formats
The CMX7032/CMX7042 can be configured to drive either a two-point VCO and Reference modulator or
an I/Q modulator by selecting the appropriate Config task (see User Manual section 9.19.1).
Typical Tx spectrum plots for both modes are shown below (generated by modulating a signal generator
with the outputs of MOD1 and MOD2 and then analysing the signal on a spectrum analyser). Note that
these plots represent the steady-state transmission and so are shown with the Class A and Class B-
SOTDMA spectrum mask (-70dBc). The Class B–CSTDMA standard specifies a slotted transmission with
a mask at –60dBc.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 38 D/7032/42_FI1.2/12
Table 9 Tx Spectrum Masks
A
LN
Mixer
-20 dBm
LN
RBW
1 kHz
VBW
1 kHz
SWT
150 ms
1SA
1MAX
RF Att
10 dB
Ref Lvl
-1.9 dBm
Ref Lvl
-1.9 dBm
Unit
dB
6 kHz/
Center
161.9753006 MHz
Span
60 kHz
-90
-80
-70
-60
-50
-40
-30
-20
-10
-100
0
1
Marker 1 [T1]
-1.88 dBm
161.97596192 MHz
1 [T1] -1.88 dBm
161.97596192 MHz
61993_25
Date: 29.AUG.2006 16:09:56
A
LN
Mixer
-20 dBm
Unit
dBm
Ref Lvl
0 dBm
Ref Lvl
0 dBm
RF Att
20 dB
LN
SWT
150 ms
Center
161.975 MHz
Span
60 kHz
6 kHz/
RBW
1 kHz
VBW
1 kHz
1SA
1MAX
-90
-80
-70
-60
-50
-40
-30
-20
-10
-100
0
61993_25
Date: 30.AUG.2006 14:30:14
I/Q Tx spectrum mask
2-point Tx spectrum mask
A
LN
Mixer
-20 dBm
Unit
dBm
Ref Lvl
0 dBm
Ref Lvl
0 dBm
RF Att
20 dB
LN
Center
161.975 MHz
Span
500 kHz
50 kHz/
RBW
1 kHz
VBW
1 kHz
SWT
1.25 s
1SA
2SA
1VIEW
2MAX
2MAX
2SA
-90
-80
-70
-60
-50
-40
-30
-20
-10
-100
0
1
1
Delta 1 [T1]
-74.17 dB
99.19839679 kHz
1 [T1] -1.98 dBm
161.97449900 MHz
1 [T1] -74.17 dB
99.19839679 kHz
61993_25
Date: 29.AUG.2006 16:04:44
A
LN
Mixer
-20 dBm
Unit
dBm
Ref Lvl
0 dBm
Ref Lvl
0 dBm
RF Att
20 dB
Center
161.975 MHz
Span
500 kHz
50 kHz/
LN
RBW
1 kHz
VBW
1 kHz
SWT
1.25 s
2SA
1VIEW
2VIEW
2VIEW
2SA
1SA
-90
-80
-70
-60
-50
-40
-30
-20
-10
-100
0
61993_25
Date: 30.AUG.2006 14:29:11
I/Q wideband spectrum
2-point wideband spectrum
(lower trace shows un-modulated signal generator)
7.7 Reception
The CMX7032/CMX7042 has two receive channels (Rx1 and Rx2) which are capable of receiving AIS
data in either raw mode or burst mode, and either of which may be configured for DSC reception (FSK
1200 baud) in raw or formatted mode. The Rx1 (Input1) and Rx2 (Input2) channels can be configured and
operated independently.
7.7.1 AIS Burst Mode Receive
The operation of receive channel Rx1 in AIS burst mode is described below (the operation of receive
channel Rx2 in AIS burst mode is essentially identical to that of Rx1).
In AIS burst mode, once an RXB1 task has been issued, the Rx1 channel state changes to Receiving
when a valid training sequence and start flag are detected. The CMX7032/CMX7042 then performs NRZI
decoding and bit de-stuffing on the received data stream, and calculates the CRC checksum.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 39 D/7032/42_FI1.2/12
Note: in AIS burst mode, the data words are automatically reversed so that they are presented to the host
most significant bit first. At the end of the message the receive channel state changes from Receiving to
either Idle or one of four error states (below). At the same time, an “Rx State Change” interrupt is flagged.
The four error conditions that the CMX7032/CMX7042 can detect in a received message (in burst mode)
are:
Message too long or missing end flag
This indicates that the received message, after bit de-stuffing, is too long to fit into the internal
message buffer. This condition could be caused by a missing or corrupted end flag.
CRC mismatch
This indicates that the received frame checksum does not match that calculated by the
CMX7032/CMX7042, most probably as the result of one or more message bits being corrupted.
New frame header found when message buffer full
This happens if the internal message buffers are still in use when another message arrives. This is
caused by a failure of the host µC to read the received messages out quickly enough.
End flag not on byte boundary
This indicates that the received message, after bit de-stuffing, is not a multiple of 8 bits. Assuming
that the message was transmitted correctly, probably caused by an end flag being missed due to
noise, and a subsequent message’s start flag being mis-identified as the expected end flag or a bit
error causing the bit de-stuffer to fail.
If any one of these error conditions is detected in a received message the CMX7032/CMX7042 discards
the message data.
Messages with a CRC error may be reported back to the host if the appropriate bit in the System Options
Config register has been set. The CRC error state is reported in the Status2 register. The host should
implement its own validity checks on messages received with a CRC error.
If a message with no error is found, the Rx1 channel state changes from Receiving to Idle (causing an “Rx
State Change” interrupt); the decoded message, comprising the burst information, three training sequence
bytes, start flag, message payload, CRC bytes and end flag, is then copied to one of the
CMX7032/CMX7042’s internal message buffers. When its turn comes around to be read out, it is copied to
the Rx1 Data Buffer and an “R1BRDY” interrupt is generated. At this point the host can issue Read Data
tasks to read back the burst and its associated parameters. Note: a new message will only generate an
“R1BRDY” interrupt when any previous message has been read out from the Rx1 Data Buffer in its
entirety.
The Rx1 channel state will stay in Idle until another RXB task is issued.
For any particular message, the three received (NRZI-decoded) training bytes in AIS burst mode will all be
either $55 or $AA depending on the configuration of the remote transmitter, although the first few bits may
be corrupted depending on the power-up characteristics of the remote transmitter and local receiver
circuits.
The host must read the Rx data buffers sufficiently quickly to avoid an overflow condition occurring. This is
only likely in a very heavily loaded AIS network. The worst case would involve the reception of a 5-slot
burst followed by a single slot and then a third burst in contiguous slots. In this case the host would need to
read the entire 5-slot burst out of the Rx Data buffer during reception of the single slot burst, such that the
buffer is then available for the third burst in the sequence. This is further compounded by the need to
monitor both Rx channels. Single slot AIS messages contain 168bits of data, which can be read by the
host in 3 x C-BUS RxData Read tasks. The maximal length 5-slot message contains upto 840 bits which
can be read by the host in 15 x C-BUS RxData Read tasks during the 26ms of a single slot. This implies
that the C-BUS must be running at a speed greater than 128kHz.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
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7.7.2 AIS Raw Mode Receive
The operation of receive channel Rx1 in AIS raw mode is described below (the operation of receive
channel Rx2 in AIS raw mode is essentially identical to that of Rx1, but is controlled through its own set of
tasks). Note that both channels operate in either Raw or Burst mode, it is not possible to select AIS Raw
mode on one channel and AIS Burst mode on the other.
In AIS raw mode, the Rx RAW bit in the Command register, $C8 must be set. The CMX7032/CMX7042
then searches the Rx1 channel for a header (training + start flag sequence) to detect the start of a
message, then transfers the three training bytes and the start flag to the Rx1 Data buffer. The number of
subsequent words transferred to the buffer is set by the value in the RxData Count register, which is read
whenever the RXR1 task is executed. R1BRDY bit will be set when the programmed number of words
have been transferred. The data can then be read back using Data Read tasks. A new RXR task should
then be executed if it is required to recover further data words. It is the responsibility of the µC to perform
all HDLC/NRZI decoding, CRC checking and end flag detection. The demodulated byte stream continues
even after the end of a message and in the absence of a received signal (the data will then be
indeterminate. Reception can be halted by issuing an AbortRx1/2 task.
Bit ordering of the received data in AIS raw mode is the same as in Tx AIS raw mode, i.e. the received bits
are packed into words most significant bit first. As the AIS message structure requires message bytes to
be transmitted least significant bit first, the µC must ensure that during the process of HDLC/NRZI
decoding that the resulting data are correctly reversed. Depending on the configuration of the remote
transmitter, one of four different types of NRZI encoded training bytes may be received – this situation
arises because the AIS specification allows a transmitter’s NRZI encoder to start in either of its two
quiescent states, and the pre-NRZI encoded training bytes can also be one of two different types ($55 or
$AA). Therefore, for any particular message, the three received training bytes in AIS raw mode will all be
either $33, $66, $99 or $CC, although the first few bits may be corrupted depending on the power-up
characteristics of the remote transmitter and local receiver circuits.
In AIS raw mode, whenever an Rx1 state reset is performed (by issuing an AbortRx1 task) the channel
state becomes Idle. This changes to Receiving when the first valid training sequence and start flag have
been detected, where it remains until another Rx1 state reset occurs.
In Raw mode a single Rx Data buffer is used, however it is 4 words longer than the equivalent Burst mode
buffer as it does not contain any burst information.
7.7.3 DSC Receive
Either the Rx1 or Rx2 channel can be configured for DSC reception. The CMX7032/CMX7042 first applies
6dB/octave de-emphasis to the received signal, then demodulates the resulting 1200 baud FSK data. Only
one of the channels at a time can be configured for DSC reception. DSC reception can operate in either
Raw or Formatted mode. Formatted mode will significantly reduce the amount of data transferred to the
host and simplify the host processing requirements. It is enabled by setting the Command register ($C8)
bit 6 to 1.
In Formatted mode, the CMX7032/CMX7042 modem will check the incoming bit stream for a valid
sequence of phasing characters (3x Rx, 2x Dx+ Rx or Dx + 2 x Rx) and then report any correctly decoded
characters to the host. The conversion from 10-bit “emitted signal” data to 7-bit characters as well as
resolution of the time-diversity error detection is handled by the modem. The characters are packed into
the 16-bit register as two 7 bit characters and an additional error indication bit (bits 15 and 7). In the case
where an odd number of characters has been received, the unused field will be reported as '0000000' and
the error bit set to 1.
In Raw mode, the received data is packed into 16-bit words for onward transmission to the µC. The
CMX7032/CMX7042 makes no attempt to perform dot pattern or data phasing detection, those functions
must be performed by the host µC. No attempt is made to correctly align data, it is simply packed into
words (most significant bit first) as it arrives. To select Raw mode, Command register ($C8) bit 6 should
be cleared to 0.
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2011 CML Microsystems Plc 41 D/7032/42_FI1.2/12
On entering DSC mode, the buffers should be flushed before starting DSC data can be received.
e.g. For Rx1 channel reception, the sequence of C-BUS commands would be:
$C1 = $0001 ; select DSC on Rx1
$C8 = $0001 ; reset Rx1
$C8 = $0042 ; enable Rx1, Formatted mode
The modem will not report valid data until it has correctly received the initial phasing sequence. Once the
Phasing sequence has been detected, the modem’s internal DPLL bandwidth will be automatically
reduced to improve the error performance. If one of the time-diversity received characters is in error, only
the correct one will be reported. If both characters have errors, the last one received will be reported, with
bit 7 (MSB) set. The characters reported back will correspond to the data sequence (see Figure 14)
3
:
A A B1 B2 B3 B4 B5 C D1 D2 D3 D4 D5 E1 E2 F1 F2 F3 G1 G2 G3 H I
Once the H and I fields have been received by the host, the modem will return to searching for the phasing
sequence.
Dot
Pattern
DX/RX
A
B
C
D
E
F
G
H
I
Phasing
Sequence
Format
Specifier
Called Party
Address
Category
Self-
identification
Tele-
command
Message
Frequency
Message
Frequency
Message
End of
Sequence
Error-check
Character
2 identical
characters
5 characters
1 character
5 characters
2 characters
3 characters
3 characters
3 identical
DX
characters
1 Rx
character
1 character
Dot pattern
D
X
D
X
D
X
D
X
D
X
D
X
A
A
B
l
B
2
B
3
R
4
B
5
C
D
l
D
2
D
3
D
4
D
5
E
l
E
2
F
l
F
2
F
3
G
l
G
2
G
3
H
I
H
H
R
X
7
R
X
6
R
X
5
R
X
4
R
X
3
R
X
2
R
X
1
R
X
0
A
A
B
l
B
2
B
3
B
4
B
5
C
D
1
D
2
D
3
D
4
D
5
E
l
E
2
F
l
F
2
F
3
G
l
G
2
G
3
H
I
Figure 14 DSC Format
3
The particular sequence shown here corresponds to the example given in ITU-R M.493-11. Different
Telecommands will produce different sequences of varying lengths.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 42 D/7032/42_FI1.2/12
7.7.4 Receive Example
The following detailed example describes the process of receiving an AIS message in Burst mode, on Rx
channel 1.
Table 10 AIS Burst Receive Example
Description
Cmd Reg
Free
DataTask
R1BRDY
Rx1B
OVF
1
The host should ensure that the R1BRDY, Data task and
CmdReg Free bits are set.
1
1
1
0
2
The host issues an RXB1 Modem task to receive an AIS
burst. Note that the Rx Burst mode bit must be set.
0
1
1
0
3
Device executes the Modem task
1
1
0
0
4
Device waits for a training sequence and start flag, then
begins to demodulate and decode data. The Rx state
changes from Idle to receiving. If the burst has a correct
CRC, the result is placed in the data buffer, if not, it is
discarded. An Rx State Change is issued and the Rx state
changes from receiving to idle, or an error condition.
1
1
1
0
5
The host issues a DataWordResetN_Rx1 Data Task .
0
1
1
0
6
Device reads the Command register and notes task types
1
0
1
0
7
Device carries out the Data task by copying the first N data
words of the data buffer into the Read Data registers.
1
1
1
0
8
The above 3 steps can be repeated (Using DataWordN
tasks) to read many words out of the device.
7.7.5 Rx Tasks
AbortRx1/Rx2
This causes the current task on the specified Rx channel to abort. It also clears the modem buffer
of the specified Rx channel.
RxB1/2: Receive Burst on Rx1/Rx2
This causes the specified Rx channel to wait for a good training sequence and start flag, then
demodulate, decode and store the burst in its data buffer. See section 7.7.1 for a detailed
discussion of AIS burst reception. The recovered data can be read by the host issuing an
appropriate Data Task. The first four words of the buffer contain the burst information:
Word1 ($A9) – Burst length in bytes.
Word2 ($AA) – Value proportional to DC offset of Rx Input.
Word3 ($B8) – Time of arrival, measured in 24kHz ticks from the SLOTCLK.
Word4 ($B9) – Slot Counter at Time of Arrival
Note: RXB1/2 tasks can only be issued when the Rx Raw bit is cleared to 0.
RxR1/2: Receive N Raw words on Rx1/Rx2
This causes the specified Rx channel to wait for a good training sequence and start flag, then
demodulate and store N words in its Data buffer. N is specified in the Rx data count register. Burst
information is NOT recorded in Raw mode, so there are an additional 4 words available in the
Data Buffer compared with Burst mode operation.
Note: RxR tasks can only be issued when the Rx Raw mode bit is set to 1.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 43 D/7032/42_FI1.2/12
7.8 Configuration Tasks and Codes
The device executes Configuration Tasks while in configuration mode. (See section 7.4.2 for a description
of device operating modes and how to change between them, and User Manual section 9.19 for more
details on a particular task). These tasks and their data are used to configure device subsystems.
Data required for the Configuration Task is loaded into the device using a Data Task, which can be
executed at the same time as the Configuration Task if it requires less than four words.
Table 11 Configuration Tasks
Configuration Task
Words
Description
User Manual
section
NULL
0
Do nothing
EXIT_CONFIG
0
Return to Normal mode
Tx I/Q or 2-point
1
Sets MOD1 and MOD2 output format (2-point or I/Q)
9.19.1
Tx MOD levels
1
Sets output levels on MOD1 and MOD2 signal pins
9.19.2
RSSI_lookup
128
Loads RSSI calibration data
9.19.3
RSSI_window
2
Sets RSSI window timing and length
9.19.4
RSSI_gain
1
Sets RSSI gain factor
9.19.5
CSTDMA_gain
1
Sets CSTDMA gain factor
9.19.6
Tx_sequence
18
Loads Tx sequence commands
9.19.7
Sleep Timing
2
Sets Rx Sleep timing
9.19.8
RAMDAC load
3 or 67
Configures RAMDAC and loads data table
9.19.9
Device Ident
2
Reads back the Device Ident and Version number
9.19.10
Enter Deep Sleep
0
Enter Deep Sleep mode
9.19.11
Leave Deep Sleep
0
Leave Deep Sleep mode
9.19.12
Initialise Slot Counter
1
Set Slot counter to given value
9.19.13
System Options
1
Xtal frequency and CRC checking
9.19.14
Set ToA Compensation
1
Set Time of Arrival compensation value
9.19.15
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7.9 RF Synthesiser (CMX7032 only)
The CMX7032 includes two Integer-N RF synthesisers, each comprising a divider, phase comparator and
charge pump. The divider has two sets of N and R registers: one set can be used for transmit and the
other for receive. The division ratios can be set up in advance by means of C-BUS registers. Then, a
single C-BUS command will change over from the transmit to the receive division ratios, or vice versa,
enabling a fast turnaround.
External RF components are needed to complete the synthesiser circuit. A typical schematic for one
synthesiser, with external components, is shown in Figure 15.
Figure 15 Example RF Synthesiser Components
R31
0
C31
820pF
R32
18k
C32
8.2nF
R33
18k
C33
680pF
C34
1nF
C35
1nF
Resistors 5%, capacitors and inductors 20% unless otherwise stated.
Note: R31 is chosen within the range 0 to 30k and selects the nominal charge pump current.
It is recommended that C34 and C35 are kept close to the VCO and that the stub from the VCO to the
CMX7032 is kept as short as possible. The loop filter components should be placed close to the VCO.
Both RF synthesisers utilise on-chip phase locked loops (PLLs) of the same design, together with external
VCOs and loop filters. The VCOs need to have good phase noise performance although it is likely that the
high division ratios used will result in the dominant noise source being the reference oscillator. The phase
detectors are of the phase-frequency type with a high impedance charge pump output requiring just
passive components in the loop filter. Lock detect functions are built in to each synthesiser and the status
reported via C-BUS. A transition to out-of-lock can be detected and communicated via a C-BUS interrupt
to the host µC. This can be important in ensuring that the transmitter cannot transmit in the event of a fault
condition arising.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 45 D/7032/42_FI1.2/12
Figure 16 Single RF PLL Block Diagram
The two RF phase locked loops (PLLs) are programmable to any frequency in the range 100MHz to
600MHz. Figure 16 is a block diagram of one PLL. The RF synthesiser clock is the same 9.6MHz or
19.2MHz clock as is used by the baseband circuitry. The RF synthesiser clock is common to both PLLs.
The charge pump supply (CPVDD) is also common to both PLLs. The RF input pins (RFnN and RFnP),
CPnOUT, ISETn and RFVSS pins are PLL specific and designated as either RF1P, RF1N, CP1OUT,
ISET1, RFVSS or RF2P, RF2N, CP2OUT, ISET2, RFVSS on the Signal List in section 3. The N and R
values for Tx and Rx modes are PLL specific and can be set from the host µC via the C-BUS. Various PLL
specific status signals are also accessible via C-BUS. The divide by N counter is 20 bits; the R counter is
13 bits.
The PLL step size (comparison frequency) is programmable: to minimise the effects of phase noise this
should be kept as high as possible. This can be set as low as 2.5kHz (for a reference input of 20MHz or
less), or up to 200kHz – limited only by the performance of the phase comparator.
The frequency for each PLL is set by using two registers: an ‘R’ register that sets the division value of the
input reference frequency to the comparison frequency (step size), and an ‘N’ register that sets the division
of the required synthesised frequency from the external VCO to the comparison frequency. This yields the
required synthesised frequency (Fs), such that:
Fs = (N / R) x FREF where FREF is the selected reference frequency
Since the set-up for the PLLs takes 4 x “RF PLL Data register” writes it follows that, while updating the PLL
settings, the registers may contain unwanted or intermediate values of bits. These will persist until the last
register is written. It is intended that users should change the content of the “RF PLL Data register” on a
PLL that is disabled, powersaved or selected to work from the alternate register set (“Tx” and “Rx” are
alternate register sets). There are no interlocks to enforce this intention. The names “Tx” and “Rx” are
arbitrary and may be assigned to other functions as required. They are independent sets of registers, one
of which is selected to command each PLL by changing the settings in the RF PLL Control register, $B3.
Other parameters for the PLLs are the charge pump setting (high or low). Two levels of charge pump gain
are available to the user, to facilitate the possibility of locking at different rates under program control. A
current setting resistor (R31) is connected between the ISETn pin (one for each PLL system) and the
respective RFVSS. This resistor will have an internally generated band gap voltage expressed across it
and may have a value of 0 to 30k, which (in conjunction with the on-chip series resistor of 9.6k) will
give charge pump current settings over a range of 2.5mA down to 230µA (including the control bit variation
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 46 D/7032/42_FI1.2/12
of 4 to 1). The value of the current setting resistor (R31) is determined in accordance with the following
formulae:
gain bit set to 1: R31 (in ) = (24/Icp) – 9600
gain bit cleared to 0: R31 (in ) = (6/Icp) – 9600
where Icp is the charge pump current (in mA).
Note that the charge pump current should always be set to at least 230µA.
The 'gain bit' refers to either bit 3 or bit 11 in the RF PLL Control register, $B3.
For optimum performance, a common master clock should be used for the RF synthesisers (RFCLK) and
the baseband sections (Main and Auxiliary System Clocks). Using unsynchronised clocks can result in
spurious products being generated in the synthesiser output and in some cases difficulty may be
experienced with obtaining lock in the RF synthesisers. Typical external components for a complete RF
synthesiser are shown in Figure 15.
Lock Status
The lock status can be observed by reading the RF PLL Status register, $B4, and the individual lock status
bits can (subject to masking) provide a C-BUS interrupt.
The lock detector can use a tolerance of one cycle or four cycles of the reference clock (not the divided
version that is used as a comparison frequency) in order to judge phase lock. An internal shift register
holds the last three lock status measurements and the lock status bits are flagged according to a majority
vote of these previous three states. Hence, one occasional lock error will not flag a lock fail. At least two
successive phase lock events are required for the lock status to be true. Note that the lock status bits
confirm phase lock to the measured tolerance and not frequency lock. The synthesiser may take more
time to confirm phase lock with the lock status bits than the time to switch from channel to channel. The
purpose of a 4-cycle tolerance is for the case where a high frequency reference oscillator would not forgive
a small phase error.
RF Inputs
The RF inputs are differential and self-biased (when not powersaved). They are intended to be capacitively
coupled to the RF signal. The signal should be in the range 0dBm to –20dBm (not necessarily balanced).
To ensure an accurate input signal the RF should be terminated with 50Ω as close to the chip as possible
and with the “P” and “N“ inputs capacitively coupled to the input and ground, keeping these connections as
short as possible. The RF input impedance is almost purely capacitive and is dominated by package and
printed circuit board parasitics.
Guidelines for using the RF Synthesisers
RF input slew rate (dv/dt) should be 14 V/µs minimum.
The RF Synthesiser 2.5V digital supply (RFVDD) can be powered from the VDEC output pin.
RF clock sources and other, different clock sources must not share common IC components,
as this may introduce coupling into the RF. Unused ac-coupled clock buffer circuits should
be tied to a dc supply, to prevent them oscillating. By default the RF clock source is routed to
the XTAL/CLK input internally.
It is recommended that the RF Synthesisers are operated with maximum gain Iset (ie. ISETn
tied to RFVSS).
The loop components should be optimised for each VCO.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 47 D/7032/42_FI1.2/12
7.10 System Clock Synthesisers
Two System Clock outputs, SYSCLK1and SYSCLK2, are available to drive additional circuits, as required.
These are phase locked loop (PLL) clocks that can be programmed via the System Clock registers with
suitable values chosen by the user. The System Clock PLL Configuration registers ($AB and $AD) control
the values of the VCO Output divider and Main Divide registers, while the System Clock Ref. Configuration
registers ($AC and $AE) control the values of the Reference Divider and signal routing configurations. The
PLLs are designed for a reference frequency of 96kHz.
The System Clock output divider stages are designed so that they have a 1:1 Mark-to-Space ratio when an
even divide number is selected.
Ref CLK div
/1 to 512
$AC b0-8
PD
VCO
PLL div
/1 to 1024
$AB b0-9
LPF
SysCLK1
Ref
SysCLK1
Div
VCO op div
/1 to 64
$AB b10-15
SysCLK1
Pre-CLK
$AC b11-15
SysCLK1
Output
384kHz-50MHz
48 - 192kHz
(96kHz typ)
SysCLK1 VCO
24.576-
98.304MHz
(49.152MHz typ)
Ref CLK div
/1 to 512
$AE b0-8
PD
VCO
PLL div
/1 to 1024
$AD b0-9
LPF
SysCLK2
Ref
SysCLK2
Div
VCO op div
/1 to 64
$AD b10-15
SysCLK2
Pre-CLK
$AE b11-15
SysCLK2
Output
384kHz-50MHz
48 - 192kHz
(96kHz typ)
SysCLK2 VCO
24.576-
98.304MHz
(49.152MHz typ)
MainCLK
OSC 9.6MHz Xtal or
19.2MHZ Clock
to RF Synthesiser
Ref CLK selection
Figure 17 System Clock Generation
The CMX7032/CMX7042 includes a 2-pin crystal oscillator circuit. This can either be configured as a
9.6MHz xtal oscillator, or the XTAL/CLK input can be driven by an externally generated 19.2MHz clock.
Note that, at power-on, the CMX7032 will provide the XTAL/CLK input to both System Clock output pins,
whereas the CMX7042 will inhibit both outputs are until they are enabled by a host command over the C-
BUS.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 48 D/7032/42_FI1.2/12
7.11 Powersave
The CMX7032/CMX7042 implements a comprehensive powersaving scheme which will automatically
enable the sections of the device that are required and return them to their powersaved state when no
longer needed. In addition, a user defined Sleep mode maybe enabled which allows the device to drop into
power-saving mode should a Receiver channel not detect any activity at the start of the AIS burst. This
feature should be used with care to ensure that any peripheral circuits are powered-up again in time to
receive the following burst correctly.
When an Rx channel enters or leaves Sleep mode, an Rx State IRQ may be asserted, which allows the
host to powersave other external circuits under its control.
A “Deep Sleep” mode is also available through the Configuration mode which halts all signal processing
activity and allows the analogue functions to be disabled so reducing power consumption to the lowest
level – see section 7.4.14
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 49 D/7032/42_FI1.2/12
7.12 C-BUS Register Summary
Table 12 C-BUS Registers
ADDR.
(hex)
REGISTER
Word Size
(bits)
$01
W
C-BUS RESET
0
$A7
W
Data Write1
16
$A8
W
Data Write 2
16
$A9
R
Data Read 1
16
$AA
R
Data Read 2
16
$AB
W
System Clk 1 PLL Data
16
$AC
W
System Clk 1 Ref
16
$AD
W
System Clk 2 PLL Data
16
$AE
W
System Clk 2 Ref
16
$AF
Reserved
$B0
Reserved
$B1
W
Input/Output Gain and Routing
16
$B2
W
RF PLL Data
16
$B3
W
RF PLL Control
16
$B4
R
RF PLL Status
8
$B5
W
Rx Raw Data Word Counter
16
$B6
W
Data Write 3
16
$B7
W
Data Write 4
16
$B8
R
Data Read 3
16
$B9
R
Data Read 4
16
$BA
R
RSSI1
16
$BB
R
RSSI2
16
$BC
Reserved
$BD
Reserved
$BE
Reserved
$BF
Reserved
$C0
W
Power Down
16
$C1
W
Mode
16
$C2
W
CS Threshold
16
$C3
Reserved
$C4
Reserved
$C5
R
Status 2
16
$C6
R
Status
16
$C7
Reserved
$C8
W
Command
16
$C9
R
ADC Data
16
$CA
Reserved
$CB
Reserved
$CC
Reserved
$CD
Reserved
$CE
W
Interrupt Mask
16
$CF
Reserved
All other C-BUS addresses (including those not listed above) are either reserved for future use or allocated
for production testing and must not be accessed in normal operation.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 50 D/7032/42_FI1.2/12
8 Performance Specification
8.1 Electrical Performance
8.1.1 Absolute Maximum Ratings
Exceeding these maximum ratings can result in damage to the device.
Min.
Max.
Unit
Supply: DVDD- DVSS
0.3
4.5
V
AVDD- AVSS
0.3
4.5
V
RFVDD- RFVSS
0.3
4.5
V
CPVDD- RFVSS
0.3
4.5
V
Voltage on any pin to DVSS
0.3
DVDD + 0.3
V
Voltage on any pin to AVSS
0.3
AVDD + 0.3
V
Voltage on any pin to RFVSS (excluding CPVDD)
0.3
RFVDD + 0.3
V
Current into or out of any power supply pin (excluding VBIAS)
(i.e. VDEC, AVDD, AVSS, DVDD, DVSS, CPVDD, RFVDD or RFVSS)
30
+30
mA
Current into or out of any other pin
20
+20
mA
Voltage differential between power supplies:
DVDD and AVDD or CPVDD
0
0.3
V
AVDD and CPVDD
0
0.3
V
DVSS and AVSS or RFVSS
0
50
mV
AVSS and RFVSS
0
50
mV
All Packages
Min.
Max.
Unit
Storage Temperature
55
+125
°C
Operating Temperature
40
+85
°C
Q1 Package (64-pad VQFN)
Min.
Max.
Unit
Total Allowable Power Dissipation at Tamb = 25°C
–
3500
mW
... Derating
–
35.0
mW/°C
Q3 Package (48-pad VQFN)
Min.
Max.
Unit
Total Allowable Power Dissipation at Tamb = 25°C
–
1750
mW
... Derating
–
17.5
mW/°C
L9 Package (64-pin LQFP)
Min.
Max.
Unit
Total Allowable Power Dissipation at Tamb = 25°C
–
1690
mW
... Derating
–
16.9
mW/°C
L4 Package (48-pin LQFP)
Min.
Max.
Unit
Total Allowable Power Dissipation at Tamb = 25°C
–
1600
mW
... Derating
–
16.0
mW/°C
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 51 D/7032/42_FI1.2/12
8.1.2 Operating Limits
Correct operation of the device outside these limits is not implied.
Notes
Min.
Max.
Unit
Supply Voltage:
DVDD – DVSS
3.0
3.6
V
AVDD – AVSS
3.0
3.6
V
CPVDD – RFVSS
3.0
3.6
V
RFVDD – DVSS
1
2.25
2.75
V
VDEC – DVSS
2
2.25
2.75
V
Operating Temperature
40
+85
°C
Clock Frequency
9.6
19.2
MHz
Function ImageTM size
24
46
kBytes
Notes:
1
The VDEC supply is automatically created from DVDD by the on-chip voltage regulator.
2
The RFVDD supply can be supplied from the VDEC supply, if preferred.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 52 D/7032/42_FI1.2/12
8.1.3 Operating Characteristics
For the following conditions unless otherwise specified:
External components as recommended in Figure 2.
Maximum load on digital outputs = 30pF.
Clock Frequency = 19.2MHz (20ppm); Tamb = 40°C to +85°C.
AVDD = DVDD = CPVDD = 3.0V to 3.6V; RFVDD = 2.25V to 2.75V.
Reference signal level = 300mV pk-pk with AVDD = 3.3V.
Signal levels track with supply voltage, so scale accordingly.
Signal to Noise Ratio (SNR) in bit rate bandwidth.
Input stage gain = 0dB. Output stage attenuation = 0dB.
DC Parameters
Notes
Min.
Typ.
Max.
Unit
Supply Current
21
All Powersaved (Deep Sleep mode)
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
8
100
µA
AIDD (AVDD = 3.3V)
–
4
20
µA
RFIDD (CPVDD = 3.3V, RFVDD = 2.5V)
–
4
20
µA
Rx Mode
22
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
14.4
–
mA
AIDD (AVDD = 3.3V)
–
5.8
–
mA
Rx Mode (Sleep Enabled)
22
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
10
–
mA
AIDD (AVDD = 3.3V)
–
1.8
–
mA
Tx Mode
22
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
20
–
mA
AIDD (AVDD = 3.3V)
–
11
–
mA
Additional current for RF Synthesiser
23
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
0
–
mA
AIDD (AVDD = 3.3V)
–
0
–
mA
RFIDD (CPVDD = 3.3V, RFVDD = 2.5V)
–
2.5
4.5
mA
Additional current for Auxiliary
System Clock (output running at 4MHz)
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
250
–
µA
AIDD (AVDD = 3.3V)
–
300
–
µA
Additional current for Auxiliary ADC
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
50
–
µA
AIDD (AVDD = 3.3V)
–
1
–
µA
Additional current for each Auxiliary DAC
DIDD (DVDD = 3.3V, VDEC = 2.5V)
–
0
–
mA
AIDD (AVDD = 3.3V)
–
200
–
µA
CLK
25
Input Logic 1
70%
–
–
DVDD
Input Logic 0
–
–
30%
DVDD
Input current (Vin = DVDD)
–
–
40
µA
Input current (Vin = DVSS)
40
–
–
µA
C-BUS Interface and Logic Inputs
Input Logic 1
70%
–
–
DVDD
Input Logic 0
–
–
30%
DVDD
Input Leakage Current (Logic 1 or 0)
1.0
–
1.0
µA
Input Capacitance
–
–
7.5
pF
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 53 D/7032/42_FI1.2/12
DC Parameters
Notes
Min.
Typ.
Max.
Unit
C-BUS Interface and Logic Outputs
Output Logic 1, (IOH = 120µA)
90%
–
–
DVDD
Output Logic 1, (IOH = 1mA)
80%
–
–
DVDD
Output Logic 0, (IOL = 360µA)
–
–
10%
DVDD
Output Logic 0, (IOL = -1.5mA)
–
–
15%
DVDD
“Off” State Leakage Current
–
–
10
µA
IRQN (Vout = DVDD)
1.0
–
+1.0
µA
RDATA (output HiZ)
1.0
–
+1.0
µA
VBIAS
26
Output voltage offset wrt AVDD/2 (IOL < 1A)
2%
–
+2%
AVDD
Output impedance
–
22
–
k
AC Parameters
Notes
Min.
Typ.
Max.
Unit
CLK Input
'High' pulse width
31
19
–
–
ns
'Low' pulse width
31
19
–
–
ns
Input impedance (at 19.2MHz)
Powered-up
Resistance
–
150
–
k
Capacitance
–
20
–
pF
Powered-down
Resistance
–
300
–
k
Capacitance
–
20
–
pF
Clock frequency
-
19.2
–
MHz
Clock stability/accuracy
–
–
±20
ppm
Clock start up (from powersave)
–
20
–
ms
VBIAS
Start up time (from powersave)
–
30
–
ms
RxIN, Spare Input
Input impedance
34
–
> 10
–
M
Input signal range
35
–
–
10 to 90
%AVDD
Input signal envelope
0.3
2.2
Vp-p
Load resistance (feedback pins)
80
–
–
k
Amplifier open loop voltage gain
(I/P = 1mV rms at 100Hz)
–
80
–
dB
Unity gain bandwidth
–
1.0
–
MHz
Programmable Input Gain Stage
36
Gain (at 0dB)
37
0.5
0
+0.5
dB
Cumulative gain error
(wrt attenuation at 0dB)
37
1.0
0
+1.0
dB
Modulator Outputs (MOD 1, MOD 2)
Power-up to output stable
41
–
50
100
µs
Modulator Attenuators
Attenuation (at 0dB)
43
1.0
0
+1.0
dB
Cumulative attenuation error
(wrt attenuation at 0dB)
0.6
0
+0.6
dB
Output impedance
Enabled
42
–
600
–
Disabled
42
–
500
–
k
Output current range (AVDD = 3.3V)
125
–
+125
µA
Output voltage range
44
0.5
–
AVDD –0.5
V
Load resistance
20
–
–
k
ADC 1 to 4 Inputs
Source output impedance
51
–
–
24
k
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 54 D/7032/42_FI1.2/12
AC Parameters
Notes
Min.
Typ.
Max.
Unit
ADCs
Resolution
–
10
–
Bits
Input Range
–
–
10 to 90
%AVDD
Conversion time
–
21
–
µs
Input impedance
Resistance
34
–
> 10
–
M
Capacitance
–
5
–
pF
Zero error
(input offset to give ADC output = 0)
0
10
mV
Integral non-linearity
–
–
4
LSB
Differential non-linearity
53
–
–
3
LSB
DACs
Resolution
–
10
–
Bits
Settling time (to 0.5 LSB)
–
10
–
µs
Output range
–
–
10 to 90
%AVDD
Output impedance
–
250
–
k
Integral non-linearity
–
–
4
LSB
Differential non-linearity
53
–
–
1
LSB
Resistive load
5
–
–
k
Noise output voltage in 30kHz bandwidth
–
5
–
µVrms
RF Synthesiser – Phase Locked Loops (CMX7032 only)
Reference Clock Input
Frequency
64, 66
5.0
19.2
40.0
MHz
Level
61
0.5
–
2.0
Vp-p
Divide ratios (R)
62
2
–
8191
RF Synthesiser
67
Comparison frequency
–
–
500
kHz
Input frequency range
65
100
–
600
MHz
Input level (at 600MHz)
-15
–
0
dBm
Input Slew Rate
14
–
–
V/µs
Divide ratios (N)
1088
–
1048575
1Hz Normalised Phase Noise Floor
68
–
197
–
dBc/Hz
Charge pump current (high)
63
–
2.5
–
mA
Charge pump current (low)
63
–
625
–
µA
Charge pump current - voltage variation
–
10%
–
per V
Charge pump current - sink to source match
–
5%
–
of ISET
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 55 D/7032/42_FI1.2/12
Notes:
21
Tamb = 25°C, not including any current drawn from the device pins by external circuitry.
22
RF and auxiliary circuits disabled.
25
Characteristics when driving the XTAL/CLK pin with an external clock source.
26
Applies when utilising VBIAS to provide a reference voltage to other parts of the system.
When using VBIAS as a reference, VBIAS must be buffered. VBIAS must always be decoupled
with a capacitor as shown in Figure 4.
31
Timing for an external input to the XTAL/CLK pin.
34
With no external components connected, measured at dc.
35
After multiplying by gain of input circuit, with external components connected.
36
Gain applied to signal at output of buffer amplifier:RX1FB, RX2FB or SpareFB.
37
Design Value. Overall attenuation input to output has a tolerance of 0dB ±1.0dB.
41
Power-up refers to issuing a C-BUS command to turn on an output. These limits apply only if
VBIAS is on and stable.
42
Small signal impedance, at AVDD = 3.3V and Tamb = 25°C.
43
With respect to the signal at the feedback pin of the selected input port.
44
With the output driving a 20k load to AVDD/2.
51
Denotes output impedance of the driver of the auxiliary input signal,
to ensure <1 bit additional error under nominal conditions.
53
Guaranteed monotonic with no missing codes.
61
Sine wave or clipped sine wave.
62
Separate dividers provided for each PLL.
63
External ISET resistor (R31) = 0Ω (Internal ISET resistor = 9k6Ω nominally).
64
For optimum performance of the synthesiser subsystems, a common master clock should be
used for the RF Synthesisers and the baseband sections. Using unsynchronised clocks is
likely to result in spurious products being generated in the synthesiser outputs and in some
cases difficulty may be experienced in obtaining lock in the RF Synthesisers.
65
Operation outside these frequency limits is possible, but not guaranteed. Below 150MHz, a
square wave input may be required to provide a fast enough slew rate.
66
Lower input frequencies may be used subject to division ratio requirements being maintained.
67
It is recommended that RF Synthesiser 1 be used for higher frequency use
(eg: RF 1st LO) and RF Synthesiser 2 be used for lower frequency use (eg: IF LO).
68
1Hz Normalised Phase Noise Floor (PN1Hz) can be used to calculate the phase noise within
the PLL loop by: Phase Noise (in band) = PN1Hz + 20 log10(N) + 10log10(fcomparison).
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 56 D/7032/42_FI1.2/12
8.1.4 Parametric Performance
For the following conditions unless otherwise specified:
External components as recommended in Figure 2.
Maximum load on digital outputs = 30pF.
CLK Frequency = 19.2MHz (±20ppm); Tamb = 40°C to +85°C.
AVDD = DVDD = CPVDD = 3.0V to 3.6V; RFVDD = 2.25V to 2.75V.
Reference Signal Level = 300mV pk-pk with AVDD = 3.3V.
Signal levels track with supply voltage, so scale accordingly.
Signal to Noise Ratio (SNR) in bit rate bandwidth.
Input stage gain = 0dB, Output stage attenuation = 0dB.
Transmit Parameters
Notes
Min.
Typ.
Max.
Unit
AIS (GMSK 9600bps), 25kHz channel
Bit rate accuracy
–
–
±50
ppm
BT
–
0.4
–
Storage time (filter delay)
1
–
8
–
bits
Tx Buffer size
–
–
176
bytes
Receive Parameters
Notes
Min.
Typ.
Max.
Unit
AIS (GMSK 9600bps), 25kHz channel
Bit rate accuracy
–
–
±50
ppm
BT
–
0.4
–
Storage time
2
–
8
–
bits
Packet error rate (PER) limit
–
–
20%
PER with –10dB co-channel interference
3
–
–
20%
PER with 10dB SNR
4
–
–
20%
Rx Buffer Size (burst mode)
–
–
2 x176
bytes
Rx Buffer Size (raw mode)
–
–
184
bytes
DSC (FSK 1200bps, 6dB/octave de-emphasis)
Bit rate accuracy
–
–
±50
ppm
Sub-carrier
–
1700
–
Hz
Tx mark frequency
1290
1300
1310
Hz
Tx space frequency
2090
2100
2110
Hz
Storage time (filter delay)
2
–
8
–
bits
Bit error rate (BER) with 10dB SNR
4
–
–
1%
SLOT CLOCK
Rise/Fall time
–
–
1.0
µs
Notes:
1. Through GMSK/FSK transmit filter.
2. Through GMSK/FSK receive filters.
3. Measured at baseband to IEC 62287-1.
4. Measured at baseband with simulated FM channel noise.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 57 D/7032/42_FI1.2/12
8.2 C-BUS Timing
Figure 18 C-BUS Timing
C-BUS Timing
Notes
Min.
Typ.
Max.
Unit
tCSE
CSN enable to SCLK high time
100
–
–
ns
tCSH
Last SCLK high to CSN high time
100
–
–
ns
tLOZ
SCLK low to RDATA output enable time
0.0
–
–
ns
tHIZ
CSN high to RDATA high impedance
–
–
1.0
µs
tCSOFF
CSN high time between transactions
1.0
–
–
µs
tNXT
Inter-byte time
200
–
–
ns
tCK
SCLK cycle time
200
–
–
ns
tCH
SCLK high time
100
–
–
ns
tCL
SCLK low time
100
–
–
ns
tCDS
CDATA setup time
75
–
–
ns
tCDH
CDATA hold time
25
–
–
ns
tRDS
RDATA setup time
50
–
–
ns
tRDH
RDATA hold time
0
–
–
ns
Notes: 1. Depending on the command, 1 or 2 bytes of CDATA are transmitted to the peripheral MSB
(Bit 7) first, LSB (Bit 0) last. RDATA is read from the peripheral MSB (Bit 7) first, LSB (Bit 0)
last.
2. Data is clocked into the peripheral on the rising SCLK edge.
3. Commands are acted upon at the end of each command (rising edge of CSN).
4. To allow for differing µC serial interface formats C-BUS compatible ICs are able to work with
SCLK pulses starting and ending at either polarity.
5. Maximum 30pF load on IRQN pin and each C-BUS interface line.
These timings are for the latest version of C-BUS and allow faster transfers than the original C-BUS timing
specification. The CMX7032/CMX7042 can be used in conjunction with devices that comply with the
slower timings, subject to system throughput constraints.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 58 D/7032/42_FI1.2/12
8.3 SPI Timing
Figure 19 SPI Interface Timing
Serial (SPI) Bus Interface Timing
Notes
Min.
Typ.
Max.
Unit
tCK
Clock cycle time
–
16
–
Xtal Clock
Periods
tCL
Clock 'low' pulse width
–
8
–
Xtal Clock
Periods
tCH
Clock 'high' pulse width
–
8
–
Xtal Clock
Periods
tDOV
Out data valid time
–
10
80
ns
tDOH
Out data hold time
0
–
–
ns
tDS
In data set up time
20
–
–
ns
tDH
In data hold time
20
–
–
ns
tCLC
Chip select low to clock rising edge
–
4
–
Xtal Clock
Periods
tCCH
Clock falling edge to chip select high
–
2
–
Xtal Clock
Periods
Notes:
1.
The serial (SPI) bus clock frequency is the CMX7032/CMX7042 internal
(Main Clock ÷ 16) frequency. At power-on, the internal Main Clock is connected directly
to the XTAL/CLK pin. A serial memory should be chosen which is compatible with these
timings.
2.
Maximum 30pF load on each serial bus interface line.
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 59 D/7032/42_FI1.2/12
8.4 Packaging
Figure 20 Mechanical Outline for 64-pad VQFN Package (Q1)
Order as CMX7032Q1
Figure 21 Mechanical Outline for 64-pin LQFP (leaded) Package (L9)
Order as CMX7032L9
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
2011 CML Microsystems Plc 60 D/7032/42_FI1.2/12
Figure 22 Mechanical Outline for 48-pad VQFN Package (Q3)
Order as CMX7042Q3
Figure 23 Mechanical Outline for 48-pin LQFP (leaded) Package (L4)
Order as CMX7042L4
AIS Baseband IC with/without RF Synthesiser CMX7032/CMX7042
About FirmASIC
CML’s proprietary FirmASIC component technology reduces cost, time to market and development risk,
with increased flexibility for the designer and end application. FirmASIC combines Analogue, Digital,
Firmware and Memory technologies in a single silicon platform that can be focused to deliver the right
feature mix, performance and price for a target application family. Specific functions of a FirmASIC
device are determined by uploading its Function Image™ during device initialization. New
Function Images™ may be later provided to supplement and enhance device functions, expanding or
modifying end-product features without the need for expensive and time-consuming design changes.
FirmASIC devices provide significant time to market and commercial benefits over Custom ASIC,
Structured ASIC, FPGA and DSP solutions. They may also be exclusively customised where security or
intellectual property issues prevent the use of Application Specific Standard Products (ASSP’s).
Handling precautions: This product includes input protection, however, precautions should be taken to prevent device damage
from electro-static discharge. CML does not assume any responsibility for the use of any circuitry described. No IPR or circuit
patent licences are implied. CML reserves the right at any time without notice to change the said circuitry and this product
specification. CML has a policy of testing every product shipped using calibrated test equipment to ensure compliance with
this product specification. Specific testing of all circuit parameters is not necessarily performed.
