SX1231H
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SX1231H Transceiver
Low Power Integrated UHF Transceiver with On-Chip +20dBm PA
Rev 1 - Oct 2011
The SX1231H is a highly integrated RF transceiver capable
of operation over a wide frequency range, including the 433,
868 and 915 MHz license-free ISM (Industry Scientific and
Medical) frequency bands. Its highly integrated architecture
allows for a minimum of external components whilst
maintaining maximum design flexibility. All major RF
communication parameters are programmable and most of
them can be dynamically set. The SX1231H offers the
unique advantage of programmable narrow-band and wide-
band communication modes without the need to modify
external components. The SX1231H is optimized for low
power consumption while offering high RF output power and
channelized operation. TrueRF™ technology enables a low-
cost external component count (elimination of the SAW
filter) whilst still satisfying ETSI and FCC regulations.
Automated Meter Reading
Wireless Sensor Networks
Home and Building Automation
Wireless Alarm and Security Systems
Industrial Monitoring and Control
Wireless M-BUS
Europe: EN 300-220-1
North America: FCC Part 15.247, 15.249, 15.231
+20 dBm - 100 mW Power Output Capability
High Sensitivity: down to -120 dBm at 1.2 kbps
High Selectivity: 16-tap FIR Channel Filter
Bullet-proof front end: IIP3 = -18 dBm, IIP2 = +35 dBm,
80 dB Blocking Immunity, no Image Frequency response
Low current: Rx = 16 mA, 100nA register retention
Programmable Pout: -18 to +20 dBm in 1dB steps
Constant RF performance over voltage range of chip
FSK Bit rates up to 300 kb/s
Fully integrated synthesizer with a resolution of 61 Hz
FSK, GFSK, MSK, GMSK and OOK modulations
Built-in Bit Synchronizer performing Clock Recovery
Incoming Sync Word Recognition
115 dB+ Dynamic Range RSSI
Automatic RF Sense with ultra-fast AFC
Packet engine with CRC-16, AES-128, 66-byte FIFO
Built-in temperature sensor
QFN 24 Package - Operating Range [-40;+85°C]
Pb-free, Halogen free, RoHS/WEEE compliant product
GENERAL DESCRIPTION
APPLICATIONS
MARKETS
KEY PRODUCT FEATURES
ORDERING INFORMATION
Part Number Delivery MOQ / Multiple
SX1231HIMLTRT Tape & Reel 3000 pieces
LNA
Single to
Differential
Mixers
Σ/Δ
Modulators
Decimation and
& Filtering
Demodulator &
Bit Synchronizer
Interpolation
& Filtering
Modulator
Packet Engine & 66 Bytes FIFO
Control Registers - Shift Registers - SPI Interface
SPI
DIO0
RSSI AFC
Division by
2, 4 or 6
Frac-N PLL
Synthesizer
XO
32 MHz
XTAL
PA0
PA1&2
Tank
Inductor
Loop
Filter
RFIO
PA_BOOST
RESET
Power Distribution System
VBAT1&2 VR_ANA VR_DIG
VR_PA Ramp &
Control
RC
Oscillator
GND
RXTX
GND
DIO1
DIO2
DIO3
DIO4
DIO5
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Table of Contents Page
1. General Description ................................................................................................................................................ 8
1.1. Simplified Block Diagram ................................................................................................................................ 8
1.2. Pin and Marking Diagram................................................................................................................................ 9
1.3. Pin Description .............................................................................................................................................. 10
2. Electrical Characteristics....................................................................................................................................... 11
2.1. ESD Notice.................................................................................................................................................... 11
2.2. Absolute Maximum Ratings .......................................................................................................................... 11
2.3. Operating Range........................................................................................................................................... 11
2.4. Chip Specification ......................................................................................................................................... 12
2.4.1. Power Consumption ................................................................................................................................. 12
2.4.2. Frequency Synthesis ................................................................................................................................ 12
2.4.3. Receiver ................................................................................................................................................... 13
2.4.4. Transmitter ............................................................................................................................................... 14
2.4.5. Digital Specification ...................................................................................................................................15
3. Chip Description.................................................................................................................................................... 16
3.1. Power Supply Strategy.................................................................................................................................. 16
3.2. Frequency Synthesis..................................................................................................................................... 16
3.2.1. Reference Oscillator ................................................................................................................................. 16
3.2.2. CLKOUT Output ........................................................................................................................................17
3.2.3. PLL Architecture ....................................................................................................................................... 17
3.2.4. Lock Time .................................................................................................................................................. 18
3.2.5. Lock Detect Indicator................................................................................................................................ 18
3.3. Transmitter Description ................................................................................................................................. 19
3.3.1. Architecture Description ........................................................................................................................... 19
3.3.2. Bit Rate Setting ........................................................................................................................................ 19
3.3.3. FSK Modulation ........................................................................................................................................ 20
3.3.4. OOK Modulation....................................................................................................................................... 20
3.3.5. Modulation Shaping.................................................................................................................................. 21
3.3.6. Power Amplifiers ...................................................................................................................................... 21
3.3.7. High Power Settings ..................................................................................................................................22
3.3.8. Output Power Summary ........................................................................................................................... 22
3.3.9. Over Current Protection ........................................................................................................................... 22
3.4. Receiver Description ..................................................................................................................................... 23
3.4.1. Block Diagram .......................................................................................................................................... 23
3.4.2. LNA - Single to Differential Buffer ............................................................................................................ 23
3.4.3. Automatic Gain Control ............................................................................................................................ 24
3.4.4. Continuous-Time DAGC........................................................................................................................... 25
3.4.5. Quadrature Mixer - ADCs - Decimators.................................................................................................... 26
3.4.6. Channel Filter ........................................................................................................................................... 26
3.4.7. DC Cancellation ....................................................................................................................................... 27
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3.4.8. Complex Filter - OOK ............................................................................................................................... 27
3.4.9. RSSI ......................................................................................................................................................... 27
3.4.10. Cordic ..................................................................................................................................................... 28
3.4.11. FSK Demodulator ....................................................................................................................................29
3.4.12. OOK Demodulator.................................................................................................................................. 29
3.4.13. Bit Synchronizer ..................................................................................................................................... 31
3.4.14. Frequency Error Indicator....................................................................................................................... 31
3.4.15. Automatic Frequency Correction ............................................................................................................ 32
3.4.16. Optimized Setup for Low Modulation Index Systems ............................................................................. 33
3.4.17. Temperature Sensor ............................................................................................................................... 34
3.4.18. Timeout Function.................................................................................................................................... 34
4. Operating Modes .................................................................................................................................................. 35
4.1. Basic Modes.................................................................................................................................................. 35
4.2. Automatic Sequencer and Wake-Up Times .................................................................................................. 35
4.2.1. Transmitter Startup Time ...........................................................................................................................36
4.2.2. Tx Start Procedure ................................................................................................................................... 36
4.2.3. Receiver Startup Time.............................................................................................................................. 36
4.2.4. Rx Start Procedure................................................................................................................................... 38
4.2.5. Optimized Frequency Hopping Sequences .............................................................................................. 38
4.3. Listen Mode................................................................................................................................................... 39
4.3.1. Timings..................................................................................................................................................... 39
4.3.2. Criteria ...................................................................................................................................................... 40
4.3.3. End of Cycle Actions ................................................................................................................................ 40
4.3.4. Stopping Listen Mode............................................................................................................................... 41
4.3.5. RC Timer Accuracy .................................................................................................................................. 41
4.4. AutoModes .................................................................................................................................................... 42
5. Data Processing.................................................................................................................................................... 43
5.1. Overview ....................................................................................................................................................... 43
5.1.1. Block Diagram .......................................................................................................................................... 43
5.1.2. Data Operation Modes ............................................................................................................................. 43
5.2. Control Block Description.............................................................................................................................. 44
5.2.1. SPI Interface............................................................................................................................................. 44
5.2.2. FIFO ......................................................................................................................................................... 45
5.2.3. Sync Word Recognition ............................................................................................................................ 46
5.2.4. Packet Handler ......................................................................................................................................... 47
5.2.5. Control ...................................................................................................................................................... 47
5.3. Digital IO Pins Mapping................................................................................................................................. 47
5.3.1. DIO Pins Mapping in Continuous Mode ................................................................................................... 48
5.3.2. DIO Pins Mapping in Packet Mode .......................................................................................................... 48
5.4. Continuous Mode .......................................................................................................................................... 49
5.4.1. General Description.................................................................................................................................. 49
5.4.2. Tx Processing........................................................................................................................................... 49
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5.4.3. Rx Processing .......................................................................................................................................... 50
5.5. Packet Mode ................................................................................................................................................. 50
5.5.1. General Description.................................................................................................................................. 50
5.5.2. Packet Format .......................................................................................................................................... 51
5.5.3. Tx Processing (without AES).................................................................................................................... 53
5.5.4. Rx Processing (without AES) ................................................................................................................... 54
5.5.5. AES .......................................................................................................................................................... 54
5.5.6. Handling Large Packets ........................................................................................................................... 56
5.5.7. Packet Filtering......................................................................................................................................... 56
5.5.8. DC-Free Data Mechanisms ...................................................................................................................... 58
6. Configuration and Status Registers ...................................................................................................................... 60
6.1. General Description ...................................................................................................................................... 60
6.2. Common Configuration Registers ................................................................................................................. 63
6.3. Transmitter Registers .................................................................................................................................... 66
6.4. Receiver Registers........................................................................................................................................ 67
6.5. IRQ and Pin Mapping Registers.................................................................................................................... 69
6.6. Packet Engine Registers............................................................................................................................... 71
6.7. Temperature Sensor Registers ..................................................................................................................... 74
6.8. Test Registers ............................................................................................................................................... 74
7. Application Information ......................................................................................................................................... 75
7.1. Crystal Resonator Specification .................................................................................................................... 75
7.2. Reset of the Chip .......................................................................................................................................... 75
7.2.1. POR.......................................................................................................................................................... 75
7.2.2. Manual Reset ............................................................................................................................................ 76
7.3. Reference Design ......................................................................................................................................... 76
8. Packaging Information .......................................................................................................................................... 79
8.1. Package Outline Drawing.............................................................................................................................. 79
8.2. Recommended Land Pattern ........................................................................................................................ 79
8.3. Thermal Impedance ...................................................................................................................................... 80
8.4. Tape & Reel Specification............................................................................................................................. 80
9. Revision History .................................................................................................................................................... 81
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Index of Figures Page
Figure 1. Block Diagram ................................................................................................................................................ 8
Figure 2. Pin Diagram .................................................................................................................................................... 9
Figure 3. Marking Diagram ............................................................................................................................................ 9
Figure 4. TCXO Connection ........................................................................................................................................ 16
Figure 5. Transmitter Block Diagram ........................................................................................................................... 19
Figure 6. Output Power Curves ................................................................................................................................... 22
Figure 7. Receiver Block Diagram ............................................................................................................................... 23
Figure 8. AGC Thresholds Settings ............................................................................................................................. 24
Figure 9. RSSI Dynamic Curve .................................................................................................................................... 28
Figure 10. Cordic Extraction ........................................................................................................................................ 28
Figure 11. OOK Peak Demodulator Description .......................................................................................................... 29
Figure 12. Floor Threshold Optimization ..................................................................................................................... 30
Figure 13. Bit Synchronizer Description ...................................................................................................................... 31
Figure 14. FEI Process ................................................................................................................................................ 32
Figure 15. Optimized AFC (AfcLowBetaOn=1) ............................................................................................................ 33
Figure 16. Temperature Sensor Response ................................................................................................................. 34
Figure 17. Tx Startup, FSK and OOK .......................................................................................................................... 36
Figure 18. Rx Startup - No AGC, no AFC .................................................................................................................... 37
Figure 19. Rx Startup - AGC, no AFC ......................................................................................................................... 37
Figure 20. Rx Startup - AGC and AFC ........................................................................................................................ 37
Figure 21. Listen Mode Sequence (no wanted signal is received) .............................................................................. 39
Figure 22. Listen Mode Sequence (wanted signal is received) ................................................................................... 41
Figure 23. Auto Modes of Packet Handler ................................................................................................................... 42
Figure 24. SX1231H Data Processing Conceptual View ............................................................................................. 43
Figure 25. SPI Timing Diagram (single access) .......................................................................................................... 44
Figure 26. FIFO and Shift Register (SR) ..................................................................................................................... 45
Figure 27. FifoLevel IRQ Source Behavior .................................................................................................................. 46
Figure 28. Sync Word Recognition .............................................................................................................................. 47
Figure 29. Continuous Mode Conceptual View ........................................................................................................... 49
Figure 30. Tx Processing in Continuous Mode ............................................................................................................ 49
Figure 31. Rx Processing in Continuous Mode ........................................................................................................... 50
Figure 32. Packet Mode Conceptual View ................................................................................................................... 51
Figure 33. Fixed Length Packet Format ...................................................................................................................... 52
Figure 34. Variable Length Packet Format .................................................................................................................. 52
Figure 35. Unlimited Length Packet Format ................................................................................................................ 53
Figure 36. CRC Implementation .................................................................................................................................. 58
Figure 37. Manchester Encoding/Decoding ................................................................................................................. 58
Figure 38. Data Whitening ........................................................................................................................................... 59
Figure 39. POR Timing Diagram ................................................................................................................................. 75
Figure 40. Manual Reset Timing Diagram ................................................................................................................... 76
Figure 41. +13dBm Schematic .................................................................................................................................... 76
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Figure 42. +17/20dBm Schematic ............................................................................................................................... 77
Figure 43. Package Outline Drawing ........................................................................................................................... 79
Figure 44. Recommended Land Pattern ..................................................................................................................... 79
Figure 45. Tape & Reel Specification .......................................................................................................................... 80
Index of Tables Page
Table 1. SX1231H Pinouts ........................................................................................................................................... 10
Table 2. Absolute Maximum Ratings ............................................................................................................................ 11
Table 3. Operating Range ............................................................................................................................................ 11
Table 4. Power Consumption Specification .................................................................................................................. 12
Table 5. Frequency Synthesizer Specification .............................................................................................................. 12
Table 6. Receiver Specification .................................................................................................................................... 13
Table 7. Transmitter Specification ................................................................................................................................ 14
Table 8. Digital Specification ........................................................................................................................................ 15
Table 9. Bit Rate Examples .......................................................................................................................................... 20
Table 10. Power Amplifier Mode Selection Truth Table ............................................................................................... 21
Table 11. High Power Settings ..................................................................................................................................... 22
Table 12. LNA Gain Settings ........................................................................................................................................ 23
Table 13. Receiver Performance Summary .................................................................................................................. 25
Table 14. Available RxBw Settings ............................................................................................................................... 26
Table 15. Available DCC Cutoff Frequencies ............................................................................................................... 27
Table 16. Basic Transceiver Modes ............................................................................................................................. 35
Table 17. Range of Durations in Listen Mode .............................................................................................................. 39
Table 18. Signal Acceptance Criteria in Listen Mode ................................................................................................... 40
Table 19. End of Listen Cycle Actions .......................................................................................................................... 40
Table 20. Status of FIFO when Switching Between Different Modes of the Chip ......................................................... 46
Table 21. DIO Mapping, Continuous Mode .................................................................................................................. 48
Table 22. DIO Mapping, Packet Mode ......................................................................................................................... 48
Table 23. Registers Summary ...................................................................................................................................... 60
Table 24. Common Configuration Registers ................................................................................................................. 63
Table 25. Transmitter Registers ................................................................................................................................... 66
Table 26. Receiver Registers ....................................................................................................................................... 67
Table 27. IRQ and Pin Mapping Registers ................................................................................................................... 69
Table 28. Packet Engine Registers .............................................................................................................................. 71
Table 29. Temperature Sensor Registers ..................................................................................................................... 74
Table 30. Test Registers .............................................................................................................................................. 74
Table 31. Crystal Specification ..................................................................................................................................... 75
Table 32. +13dBm BOM ............................................................................................................................................... 77
Table 33. +17/20dBm BOM .......................................................................................................................................... 77
Table 34. Revision History ............................................................................................................................................ 81
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Acronyms
BOM Bill Of Materials LSB Least Significant Bit
BR Bit Rate MSB Most Significant Bit
BW Bandwidth NRZ Non Return to Zero
CCITT Comité Consultatif International
Téléphonique et Télégraphique - ITU
OOK On Off Keying
CRC Cyclic Redundancy Check PA Power Amplifier
DAC Digital to Analog Converter PCB Printed Circuit Board
ETSI European Telecommunications Standards
Institute
PLL Phase-Locked Loop
FCC Federal Communications Commission POR Power On Reset
Fdev Frequency Deviation RBW Resolution BandWidth
FIFO First In First Out RF Radio Frequency
FIR Finite Impulse Response RSSI Received Signal Strength Indicator
FS Frequency Synthesizer Rx Receiver
FSK Frequency Shift Keying SAW Surface Acoustic Wave
GUI Graphical User Interface SPI Serial Peripheral Interface
IC Integrated Circuit SR Shift Register
ID IDentificator Stby Standby
IF Intermediate Frequency Tx Transmitter
IRQ Interrupt ReQuest uC Microcontroller
ITU International Telecommunication Union VCO Voltage Controlled Oscillator
LFSR Linear Feedback Shift Register XO Crystal Oscillator
LNA Low Noise Amplifier XOR eXclusive OR
LO Local Oscillator
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This product datasheet contains a detailed description of the SX1231H performance and functionality. Please consult the
Semtech website for the latest updates or errata.
1. General Description
The SX1231H is a single-chip integrated circuit ideally suited for today's high performance ISM band RF applications. The
SX1231H's advanced features set, including state of the art packet engine greatly simplifies system design whilst the high
level of integration reduces the external BOM to a handful of passive decoupling and matching components. It is intended
for use as high-performance, low-cost FSK and OOK RF transceiver for robust frequency agile, half-duplex bi-directional
RF links, and where stable and constant RF performance is required over the full operating range of the device down to
2.4V.
The SX1231H is intended for applications over a wide frequency range, including the 433 MHz and 868 MHz European
and the 902-928 MHz North American ISM bands. Coupled with a link budget in excess of 140 dB, the advanced system
features of the SX1231H include a 66 byte TX/RX FIFO, configurable automatic packet handler, listen mode, temperature
sensor and configurable DIOs which greatly enhance system flexibility whilst at the same time significantly reducing MCU
requirements.
The SX1231H complies with both ETSI and FCC regulatory requirements and is available in a 5x 5 mm QFN 24 lead
package
1.1. Simplified Block Diagram
Figure 1. Block Diagram
LNA
Single to
Differential
Mixers
Σ/Δ
Modulators
Decimation and
& Filtering
Demodulator &
Bit Synchronizer
Interpolation
& Filtering
Modulator
Packet Engine & 66 Bytes FIFO
Control Registers - Shift Registers - SPI Interface
RSSI AFC
Division by
2, 4 or 6
Frac-N PLL
Synthesizer
XO
32 MHz
XTAL
PA0
PA1&2
Tank
Inductor
Loop
Filter
RFIO
PA_BOOST
RESET
GND
Power Distribution System
VBAT1&2 VR_ANA VR_DIG
VR_PA Ramp &
Control
RC
Oscillator
Frequency Synthesis
Receiver Blocks
Transmitter Blocks
Control Blocks
Primarily Analog
Primarily Digital
GND
SPI
DIO0
RXTX
DIO1
DIO2
DIO3
DIO4
DIO5
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1.2. Pin and Marking Diagram
The following diagram shows the pin arrangement of the QFN package, top view.
Figure 2. Pin Diagram
Figure 3. Marking Diagram
Notes yyww refers to the date code
xxxxxx refers to the lot number
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1.3. Pin Description
Table 1 SX1231H Pinouts
Note PA_BOOST can be left floating if unused
Number Name Type Description
0 GROUND -Exposed ground pad
1 VBAT1 -Supply voltage
2VR_ANA-Regulated supply voltage for analogue circuitry
3 VR_DIG -Regulated supply voltage for digital blocks
4XTA
I/O XTAL connection
5XTB
I/O XTAL connection
6 RESET I/O Reset trigger input
7DIO0
I/O Digital I/O, software configured
8 DIO1/DCLK I/O Digital I/O, software configured
9DIO2/DATA
I/O Digital I/O, software configured
10 DIO3 I/O Digital I/O, software configured
11 DIO4 I/O Digital I/O, software configured
12 DIO5 I/O Digital I/O, software configured
13 VBAT2 -Supply voltage
14 GND -Ground
15 SCK ISPI Clock input
16 MISO OSPI Data output
17 MOSI ISPI Data input
18 NSS ISPI Chip select input
19 RXTX ORx/Tx switch control: high in Tx
20 GND -Ground
21 RFIO I/O RF input / output
22 GND -Ground
23 PA_BOOST OOptional high-power PA output
24 VR_PA -Regulated supply for the PA
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2. Electrical Characteristics
2.1. ESD Notice
The SX1231H is a high performance radio frequency device. It satisfies:
Class 2 of the JEDEC standard JESD22-A114-B (Human Body Model) on all pins.
Class B of the JEDEC standard JESD22-A115-A (Machine Model) on all pins.
Class IV of the JEDEC standard JESD22-C101C (Charged Device Model) on pins 2-3-21-23-24, Class III on all other
pins.
It should thus be handled with all the necessary ESD precautions to avoid any permanent damage.
2.2. Absolute Maximum Ratings
Stresses above the values listed below may cause permanent device failure. Exposure to absolute maximum ratings for
extended periods may affect device reliability.
Table 2 Absolute Maximum Ratings
2.3. Operating Range
Table 3 Operating Range
Symbol Description Min Max Unit
VDDmr Supply Voltage -0.5 3.9 V
Tmr Temperature -55 +115 ° C
Tj Junction temperature - +125 ° C
Pmr RF Input Level - +6 dBm
DC_20dBm Duty Cycle of transmission at +20dBm output - 1 %
VSWR_20dBm Maximum VSWR at antenna port - 3:1 -
Symbol Description Min Max Unit
VDDop Supply voltage 2.4 3.6 V
Top Operational temperature range -40 +85 °C
Clop Load capacitance on digital ports - 25 pF
ML RF Input Level - 0 dBm
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2.4. Chip Specification
The tables below give the electrical specifications of the transceiver under the following conditions: Supply voltage VBAT1=
VBAT2=VDD=3.3 V, temperature = 25 °C, FXOSC = 32 MHz, FRF = 915 MHz, Pout = +13dBm, 2-level FSK modulation
without pre-filtering, FDA = 5 kHz, Bit Rate = 4.8 kb/s and terminated in a matched 50 Ohm impedance, unless otherwise
specified.
Note Unless otherwise specified, the performances in the other fr eq ue n cy ba nd s ar e sim ilar or be tte r.
2.4.1. Power Consumption
Table 4 Power Consumption Specification
2.4.2. Frequency Synthesis
Table 5 Frequency Synthesizer Specification
Symbol Description Conditions Min Typ Max Unit
IDDSL Supply current in Sleep mode - 0.1 1 uA
IDDIDLE Supply current in Idle mode RC oscillator enabled - 1.2 - uA
IDDST Supply current in Standby mode Crystal oscillator enabled - 1.25 1.5 mA
IDDFS Supply current in Synthesizer
mode
-9-mA
IDDR Supply current in Receive mode - 16 - mA
IDDT Supply current in Transmit mode
with appropriate matching, sta-
ble across VDD range
RFOP = +20 dBm, on PA_BOOST
RFOP = +17 dBm, on PA_BOOST
RFOP = +13 dBm, on RFIO pin
RFOP = +10 dBm, on RFIO pin
RFOP = 0 dBm, on RFIO pin
RFOP = -1 dBm, on RFIO pin
-
-
-
-
-
-
130
95
45
33
20
16
-
-
-
-
-
-
mA
mA
mA
mA
mA
mA
Symbol Description Conditions Min Typ Max Unit
FR Synthesizer Frequency Range Programmable 290
431
862
-
-
-
340
510
1020
MHz
MHz
MHz
FXOSC Crystal oscillator frequency See section 7.1 - 32 - MHz
TS_OSC Crystal oscillator wake-up time - 250 500 us
TS_FS Frequency synthesizer wake-up
time to PllLock signal
From Standby mode - 80 150 us
TS_HOP Frequency synthesizer hop time
at most 10 kHz away from the
target
200 kHz step
1 MHz step
5 MHz step
7 MHz step
12 MHz step
20 MHz step
25 MHz step
-
-
-
-
-
-
-
20
20
50
50
80
80
80
-
-
-
-
-
-
-
us
us
us
us
us
us
us
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2.4.3. Receiver
All receiver tests are performed with RxBw = 10 kHz (Single Side Bandwidth) as programmed in RegRxBw, receiving a
PN15 sequence with a BER of 0.1% (Bit Synchronizer is enabled), unless otherwise specified. The LNA impedance is set
to 200 Ohms, by setting bit LnaZin in RegLna to 1. Blocking tests are performed with an unmodulated interferer. The
wanted signal power for the Blocking Immunity, ACR, IIP2, IIP3 and AMR tests is set 3 dB above the nominal sensitivity
level.
Table 6 Receiver Specification
FSTEP Frequency synthesizer step FSTEP = FXOSC/219 -61.0 - Hz
FRC RC Oscillator frequency After calibration - 62.5 - kHz
BRF Bit rate, FSK Programmable 1.2 - 300 kbps
BRO Bit rate, OOK Programmable 1.2 - 32.768 kbps
FDA Frequency deviation, FSK Programmable
FDA + BRF/2 =< 500 kHz
0.6 - 300 kHz
Symbol Description Conditions Min Typ Max Unit
RFS_F FSK sensitivity, highest LNA gain FDA = 5 kHz, BR = 1.2 kb/s
FDA = 5 kHz, BR = 4.8 kb/s
FDA = 40 kHz, BR = 38.4 kb/s
-
-
-
-118
-114
-105
-
-
-
dBm
dBm
dBm
FDA = 5 kHz, BR = 1.2 kb/s * --120-dBm
RFS_O OOK sensitivity, highest LNA gain BR = 4.8 kb/s - -112 -109 dBm
CCR Co-Channel Rejection -13 -10 - dB
ACR Adjacent Channel Rejection Offset = +/- 25 kHz
Offset = +/- 50 kHz
-
37
42
42
-
-
dB
dB
BI Blocking Immunity Offset = +/- 1 MHz
Offset = +/- 2 MHz
Offset = +/- 10 MHz
-
-
-
66
71
79
-
-
-
dB
dB
dB
Blocking Immunity
Wanted signal at sensitivity
+16dB
Offset = +/- 1 MHz
Offset = +/- 2 MHz
Offset = +/- 10 MHz
-
-
-
62
65
73
-
-
-
dB
dB
dB
AMR AM Rejection , AM modulated
interferer with 100% modulation
depth, fm = 1 kHz, square
Offset = +/- 1 MHz
Offset = +/- 2 MHz
Offset = +/- 10 MHz
-
-
-
66
71
79
-
-
-
dB
dB
dB
IIP2 2nd order Input Intercept Point
Unwanted tones are 20 MHz
above the LO
Lowest LNA gain
Highest LNA gain
-
-
+75
+35
-
-
dBm
dBm
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* Set SensitivityBoost in RegTestLna to 0x2D to reduce the noise floor in the receiver
2.4.4. Transmitter
Table 7 Transmitter Specification
IIP3 3rd order Input Intercept point
Unwanted tones are 1MHz and
1.995 MHz above the LO
Lowest LNA gain
Highest LNA gain
-
-23
+20
-18
-
-
dBm
dBm
BW_SSB Single Side channel filter BW Programmable 2.6 - 500 kHz
IMR_OOK Image rejection in OOK mode Wanted signal level = -106 dBm 27 30 - dB
TS_RE Receiver wake-up time, from PLL
locked state to RxReady RxBw = 10 kHz, BR = 4.8 kb/s
RxBw = 200 kHz, BR = 100 kb/s
-
-
1.7
96
-
-
ms
us
TS_RE_AGC Receiver wake-up time, from PLL
locked state, AGC enabled
RxBw = 10 kHz, BR = 4.8 kb/s
RxBw = 200 kHz, BR = 100 kb/s
-3.0
163
ms
us
TS_RE_AGC
&AFC
Receiver wake-up time, from PLL
lock state, AGC and AFC enabled
RxBw = 10 kHz, BR = 4.8 kb/s
RxBw = 200 kHz, BR = 100 kb/s
4.8
265
ms
us
TS_FEI FEI sampling time Receiver is ready - 4.Tbit --
TS_AFC AFC Response Time Receiver is ready - 4.Tbit --
TS_RSSI RSSI Response Time Receiver is ready - 2.Tbit --
DR_RSSI RSSI Dynamic Range AGC enabled Min
Max
-
-
-115
0
-
-
dBm
dBm
Symbol Description Conditions Min Typ Max Unit
RF_OP RF output power in 50 ohms
On RFIO pin
Programmable with 1dB steps Max
Min
-
-
+13
-18
-
-
dBm
dBm
RF_OPH Max RF output power, on
PA_BOOST pin
With external match to 50 ohms - +20 - dBm
ΔRF_OP RF output power stability From VDD=2.4V to 3.6V - +/-0.3 - dB
PHN Transmitter Phase Noise 50 kHz Offset from carrier
868 / 915 MHz bands
434 / 315 MHz bands
-
-
-95
-99
-
-
dBc/
Hz
ACP Transmitter adjacent channel
power (measured at 25 kHz off-
set)
BT=0.5 . Measurement conditions as
defined by EN 300 220-1 V2.1.1
---37dBm
TS_TR Transmitter wake up time, to the
first rising edge of DCLK
Frequency Synthesizer enabled,
PaRamp = 10 us, BR = 4.8 kb/s.
- 120 - us
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2.4.5. Digital Specification
Conditions: Temp = 25°C, VDD = 3.3V, FXOSC = 32 MHz, unless otherwise specified.
Table 8 Digital Specification
Symbol Description Conditions Min Typ Max Unit
VIH Digital input level high 0.8 - - VDD
VIL Digital input level low - - 0.2 VDD
VOH Digital output level high Imax = 1 mA 0.9 - - VDD
VOL Digital output level low Imax = -1 mA - - 0.1 VDD
FSCK SCK frequency - - 10 MHz
tch SCK high time 50 - - ns
tcl SCK low time 50 - - ns
trise SCK rise time - 5 - ns
tfall SCK fall time - 5 - ns
tsetup MOSI setup time from MOSI change to SCK rising
edge
30 - - ns
thold MOSI hold time from SCK rising edge to MOSI
change
60 - - ns
tnsetup NSS setup time from NSS falling edge to SCK rising
edge
30 - - ns
tnhold NSS hold time from SCK falling edge to NSS rising
edge, normal mode
30 - - ns
tnhigh NSS high time between SPI
accesses
20 - - ns
T_DATA DATA hold and setup time 250 - - ns
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3. Chip Description
This section describes in depth the architecture of the SX1231H low-power, highly integrated transceiver.
3.1. Power Supply Strategy
The SX1231H employs an advanced power supply scheme, which provides stable operating characteristics over the full
temperature and voltage range of operation. This includes the full output power of +20dBm maintained from 2.4 to 3.6V.
The SX1231H can be powered from any low-noise voltage source via pins VBAT1 and VBAT2. Decoupling capacitors
should be connected, as suggested in the reference design, on VR_PA, VR_DIG and VR_ANA pins to ensure a correct
operation of the built-in voltage regulators.
3.2. Frequency Synthesis
The LO generation on the SX1231H is based on a state-of-the-art fractional-N PLL. The PLL is fully integrated with
automatic calibration.
3.2.1. Reference Oscillator
The crystal oscillator is the main timing reference of the SX1231H. It is used as a reference for the frequency synthesizer
and as a clock for the digital processing.
The XO startup time, TS_OSC, depends on the actual XTAL being connected on pins XTA and XTB. When using the built-
in sequencer, the SX1231H optimizes the startup time and automatically triggers the PLL when the XO signal is stable. To
manually control the startup time, the user should either wait for TS_OSC max, or monitor the signal CLKOUT which will
only be made available on the output buffer when a stable XO oscillation is achieved.
An external clock can be used to replace the crystal oscillator, for instance a tight tolerance TCXO. To do so, bit 4 at
address 0x59 should be set to 1, and the external clock has to be provided on XTA (pin 4). XTB (pin 5) should be left open.
The peak-peak amplitude of the input signal must never exceed 1.8 V. Please consult your TCXO supplier for an
appropriate value of decoupling capacitor, CD.
Figure 4. TCXO Connection
XTA XTB
32 MHz
TCXO NC
OP
Vcc
GND CD
Vcc
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3.2.2. CLKOUT Output
The reference frequency, or a fraction of it, can be provided on DIO5 (pin 12) by modifying bits ClkOut in RegDioMapping2.
Two typical applications of the CLKOUT output include:
To provide a clock output for a companion processor, thus saving the cost of an additional oscillator. CLKOUT can be
made available in any operation mode except Sleep mode and is automatically enabled at power on reset.
To provide an oscillator reference output. Measurement of the CLKOUT signal enables simple software trimming of the
initial crystal tolerance.
Note to minimize the current c onsumption of the SX1 231H, please e nsure that the CLKOUT signal is disabled when not
required.
3.2.3. PLL Architecture
The frequency synthesizer generating the LO frequency for both the receiver and the transmitter is a fractional-N sigma-
delta PLL. The PLL incorporates a third order loop capable of fast auto-calibration, and it has a fast switching-time. The
VCO and the loop filter are both fully integrated, removing the need for an external tight-tolerance, high-Q inductor in the
VCO tank circuit.
3.2.3.1. VCO
The VCO runs at 2, 4 or 6 times the RF frequency (respectively in the 915, 434 and 315 MHz bands) to reduce any LO
leakage in receiver mode, to improve the quadrature precision of the receiver, and to reduce the pulling effects on the VCO
during transmission.
The VCO calibration is fully automated. A coarse adjustment is carried out at power on reset, and a fine tuning is
performed each time the SX1231H PLL is activated. Automatic calibration times are fully transparent to the end-user, as
their processing time is included in the TS_TE and TS_RE specifications.
3.2.3.2. PLL Bandwidth
The bandwidth of the SX1231H Fractional-N PLL is wide enough to allow for:
High speed FSK modulation, up to 300 kb/s, inside the PLL bandwidth
Very fast PLL lock times, enabling both short startup and fast hop times required for frequency agile applications
3.2.3.3. Carrier Frequen cy and Resolution
The SX1231H PLL embeds a 19-bit sigma-delta modulator and its frequency resolution, constant over the whole frequency
range, and is given by:
The carrier frequency is programmed through RegFrf, split across addresses 0x07 to 0x09:
Note The Frf setting is split across 3 bytes. A change in the center frequency will only be taken into account when the
least significant byte FrfLsb in RegFrfLsb is written. This allows for more complex m odulation schemes such as m-
ary FSK, where frequency modulation is achieved by changing the programmed RF frequency.
FSTEP FXOSC
219
----------------
=
FRF FSTEP Frf 23 0(,)×=
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3.2.4. Lock Time
PLL lock time TS_FS is a function of a number of technical factors, such as synthesized frequency, frequency step, etc.
When using the built-in sequencer, the SX1231H optimizes the startup time and automatically starts the receiver or the
transmitter when the PLL has locked. To manually control the startup time, the user should either wait for TS_FS max given
in the specification, or monitor the signal PLL lock detect indicator, which is set when the PLL has is within its locking
range.
When performing an AFC, which usually corrects very small frequency errors, the PLL response time is approximately:
In a frequency hopping scheme, the timings TS_HOP given in the table of specifications give an order of magnitude for the
expected lock times.
3.2.5. Lock Detect Indicator
A lock indication signal can be made available on some of the DIO pins, and is toggled high when the PLL reaches its
locking range. Please refer to Table 21 and Table 22 to map this interrupt to the desired pins.
Note The lock detect block may indicate an un lock condition (signal toggling low) when the transmitter is FSK modulated
with large frequency deviation settings.
TPLLAFC 5
PLLBW
--------------------
=
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3.3. Transmitter Description
The transmitter of SX1231H comprises the frequency synthesizer, modulator and power amplifier blocks.
3.3.1. Architecture Description
Figure 5. Transmitter Block Diagram
3.3.2. Bit Rate Setting
When using the SX1231H in Continuous mode, the data stream to be transmitted can be input directly to the modulator via
pin 9 (DIO2/DATA) in an asynchronous manner, unless Gaussian filtering is used, in which case the DCLK signal on pin 10
(DIO1/DCLK) is used to synchronize the data stream. See section 3.3.5 for details on the Gaussian filter.
In Packet mode or in Continuous mode with Gaussian filtering enabled (refer to section 5.5 for details), the Bit Rate (BR) is
controlled by bits BitRate in RegBitrate:
Amongst others, the following Bit Rates are accessible:
LNA
Receiver Chain
RFIO
Local
Oscillator
PA0
PA1
PA2
PA_BOOST
BR FXOSC
BitRate
--------------------
=
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Table 9 Bit Rate Examples
3.3.3. FSK Modulation
FSK modulation is performed inside the PLL bandwidth, by changing the fractional divider ratio in the feedback loop of the
PLL. The large resolution of the sigma-delta modulator, allows for very narrow frequency deviation. The frequency
deviation FDEV is given by:
To ensure a proper modulation, the following limit applies:
Note no constraint applies to the modulation index of the transmitter, but the frequency deviation must exceed 600 Hz.
3.3.4. OOK Modulation
OOK modulation is applied by switching on and off the Power Amplifier. Digital control and smoothing are available to
improve the transient power response of the OOK transmitter.
Type BitRate
(15:8) BitRate
(7:0) (G)FSK
(G)MSK OOK Actual BR
(b/s)
Classical modem baud rates
(multiples of 1.2 kbps)
0x68 0x2B 1.2 kbps 1.2 kbps 1200.015
0x34 0x15 2.4 kbps 2.4 kbps 2400.060
0x1A 0x0B 4.8 kbps 4.8 kbps 4799.760
0x0D 0x05 9.6 kbps 9.6 kbps 9600.960
0x06 0x83 19.2 kbps 19.2 kbps 19196.16
0x03 0x41 38.4 kbps 38415.36
0x01 0xA1 76.8 kbps 76738.60
0x00 0xD0 153.6 kbps 153846.1
Classical modem baud rates
(multiples of 0.9 kbps)
0x02 0x2C 57.6 kbps 57553.95
0x01 0x16 115.2 kbps 115107.9
Round bit rates
(multiples of 12.5, 25 and
50 kbps)
0x0A 0x00 12.5 kbps 12.5 kbps 12500.00
0x05 0x00 25 kbps 25 kbps 25000.00
0x02 0x80 50 kbps 50000.00
0x01 0x40 100 kbps 100000.0
0x00 0xD5 150 kbps 150234.7
0x00 0xA0 200 kbps 200000.0
0x00 0x80 250 kbps 250000.0
0x00 0x6B 300 kbps 299065.4
Watch Xtal frequency 0x03 0xD1 32.768 kbps 32.768 kbps 32753.32
FDEV FSTEP Fdev 13 0(,)×=
FDEV BR
2
------- 500kHz+
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3.3.5. Modulation Shaping
Modulation shaping can be applied in both OOK and FSK modulation modes, to improve the narrowband response of the
transmitter. Both shaping features are controlled with PaRamp bits in RegPaRamp.
In FSK mode, a Gaussian filter with BT = 0.3, 0.5 or 1 is used to filter the modulation stream, at the input of the sigma-
delta modulator. If the Gaussian filter is enabled when the SX1231H is in Continuous mode, DCLK signal on pin 10
(DIO1/DCLK) will trigger an interrupt on the uC each time a new bit has to be transmitted. Please refer to section 5.4.2
for details.
When OOK modulation is used, the PA bias voltages are ramped up and down smoothly when the PA is turned on and
off, to reduce spectral splatter.
Note the transmitter must be restarted if the PaRamp setting is changed, in order to recalibrate the built-in filter.
3.3.6. Power Amplifiers
Three power amplifier blocks are embedded in the SX1231H. The first one, herein referred to as PA0, can generate up to
+13 dBm into a 50 Ohm load. PA0 shares a common front-end pin RFIO (pin 21) with the receiver LNA.
PA1 and PA2 are both connected to pin PA_BOOST (pin 23), allowing for two distinct power ranges:
A low power mode, where -2 dBm < Pout < 13 dBm, with PA1 enabled
A higher power mode, when PA1 and PA2 are combined, providing up to +20 dBm to a matched load.
When PA1 and PA2 are combined to deliver +20 dBm to the antenna, a specific impedance matching / harmonic filtering
design is required to ensure impedance transformation and regulatory compliance.
All PA settings are controlled by RegPaLevel, and the truth table of settings is given in Table 10.
Table 10 Power Amplifier Mode Selection Truth Table
Notes - To ensure correct operation at the highest power levels, please make sure to adjust the Over Current Protection
Limit accordingly in RegOcp, except above +18dBm where it must be disabled
- If PA_BOOST pin is not used (+13dBm applications and less), the pin can be left floating.
Pa0On Pa1On Pa2On Mode Power Range Pout Formula
100
PA0 output on pin RFIO -18 to +13 dBm -18 dBm + OutputPower
01 0 PA1 enabled on pin PA_BOOST -2 to +13 dBm -18 dBm + OutputPower
011
PA1 and PA2 combined on pin PA_BOOST +2 to +17 dBm -14 dBm + OutputPower
0 1 1 PA1+PA2 on PA_BOOST with high output
power +20dBm settings (see 3.3.7)
+5 to +20 dBm -11 dBm + OutputPower
Other combinations Reserved
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3.3.7. High Power Settings
The SX1231H has a high power +20 dBm capability on PA_BOOST pin, with the following settings:
Table 11 High Power Settings
Note High Power settings MUST be turned off when using PA0, and in Receive mode
The Duty Cycle of transmission at +20dBm is limited to 1%, with a maximum VSWR of 3:1 at antenna port, over the
standard operating range [-40;+85°C]. For any other operating condition, contact your Semtech representative.
3.3.8. Output Power Summary
The curves below summarize the possible PA options on the SX1231H:
Figure 6. Output Power Curves
3.3.9. Over Current Protection
An over current protection block is built-in the chip. It helps preventing surge currents required when the transmitter is used
at its highest power levels, thus protecting the battery that may power the application. The current clamping value is
controlled by OcpTrim bits in RegOcp, and is calculated with the following formula:
Note Imax sets a limit on the current drain of the Power Amplifier only, hence the maximum current dr ain of the
SX1231H is equal to Imax + IFS
Register Address Value for
High Power Value for Rx
or PA0 use Description
RegOcp 0x13 0x0F 0x1x OCP control
RegTestPa1 0x5A 0x5D 0x55 High power PA control
RegTestPa2 0x5C 0x7C 0x70 High power PA control
Pout vs. Programmed Power
-22
-18
-14
-10
-6
-2
2
6
10
14
18
22
-18 -14 -10 -6 -2 2 6 10 14 18
Pr ogram med Po w er [ dBm]
Pout [dBm]
Pout on PA0 [dBm]
Pout on PA1 [dBm]
Pout on PA1+PA2 [dBm]
Pout on PA1+PA2 with 20dBm settings [dBm]
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3.4. Receiver Description
The SX1231H features a digital receiver with the analog to digital conversion process being performed directly following
the LNA-Mixers block. The zero-IF receiver is able to handle (G)FSK and (G)MSK modulation. ASK and OOK modulation
is, however, demodulated by a low-IF architecture. All the filtering, demodulation, gain control, synchronization and packet
handling is performed digitally, which allows a very wide range of bit rates and frequency deviations to be selected. The
receiver is also capable of automatic gain calibration in order to improve precision on RSSI measurements.
3.4.1. Block Diagram
Figure 7. Receiver Block Diagram
The following sections give a brief description of each of the receiver blocks.
3.4.2. LNA - Single to Differential Buffer
The LNA uses a common-gate topology, which allows for a flat characteristic over the whole frequency range. It is
designed to have an input impedance of 50 Ohms or 200 Ohms (as selected with bit LnaZin in RegLna), and the parasitic
capacitance at the LNA input port is cancelled with the external RF choke. A single to differential buffer is implemented to
improve the second order linearity of the receiver.
The LNA gain, including the single-to-differential buffer, is programmable over a 48 dB dynamic range, and control is either
manual or automatic with the embedded AGC function.
Note In the specific case where the LNA gain is manually set by the user, the receiver will not be able to properly handle
FSK signals with a modulation index smaller than 2 at an input power greater than the 1dB compression point,
tabulated in se ction 3.4.3.
Table 12 LNA Gain Settings
LnaGainSelect LNA Gain Gain Setting
000 Any of the below, set by the AGC loop -
001 Max gain G1
010 Max gain - 6 dB G2
011 Max gain - 12 dB G3
100 Max gain - 24 dB G4
101 Max gain - 36 dB G5
110 Max gain - 48 dB G6
111 Reserved -
LNA
Single to
Differential
Mixers
Σ/Δ
Modulators
Dec imator
RSS I
AFC
RFIO
FSK
Demodulator
From
PA1
Local
Oscillator
Channel
Fi l ter
DC
Cancellation
Rx Calibration
Reference
Bypassed
in FSK
Phase
Out put
Module
Output
Complex
Fi l te r
CORDIC
OOK
Demodulator
Processing
AGC
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3.4.3. Automatic Gain Control
By default (LnaGainSe lect = 000), the LNA gain is controlled by a digital AGC loop in order to obtain the optimal sensitivity/
linearity trade-off.
Regardless of the data transfer mode (Packet or Continuous), the following series of events takes place when the receiver
is enabled:
The receiver stays in WAIT mode, until RssiValue exceeds RssiThreshold for two consecutive samples. Its power
consumption is the receiver power consumption.
When this condition is satisfied, the receiver automatically selects the most suitable LNA gain, optimizing the sensitivity/
linearity trade-off.
The programmed LNA gain, read-accessible with LnaCurrentGain in RegLna, is carried on for the whole duration of the
packet, until one of the following conditions is fulfilled:
Packet mode: if AutoRxRestartOn = 0, the LNA gain will remain the same for the reception of the following packet. If
AutoRxRestartOn = 1, after the controller has emptied the FIFO the receiver will re-enter the WAIT mode described
above, after a delay of InterPacketRxDelay, allowing for the distant transmitter to ramp down, hence avoiding a false
RSSI detection. In both cases (AutoRxRestartOn=0 or AutoRxRestartOn=1), the receiver can also re-enter the WAIT
mode by setting RestartRx bit to 1. The user can decide to do so, to manually launch a new AGC procedure.
Continuous mode: upon reception of valid data, the user can decide to either leave the receiver enabled with the same
LNA gain, or to restart the procedure, by setting RestartRx bit to 1, resuming the WAIT mode of the receiver, described
above.
Notes - the AGC procedur e must be performed while receiving preamble in FSK mode
- in OOK mode, the AGC will give better results if performed while receiving a constant “1” sequence
The following figure illustrates the AGC behavior:
Figure 8. AGC Thresholds Settings
The following table summarizes the performance (typical figures) of the complete receiver:
Towards
-125 dBm
Å AGC Reference
Å AgcThresh1
Å AgcThresh2
Å AgcThresh3
Å AgcThresh4
Pin [dBm]
Å AgcThresh5
16dB 7dB 11dB 9dB 11dB
G1 G2 G3 G4 G5 G6
Higher Sensitivity
Lower Linearity
Lower Noise Figure
Lower Sensitivity
Higher Linearity
Higher Noise Figure
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Table 13 Receiver Performance Summary
3.4.3.1. RssiThreshold Setting
For correct operation of the AGC, RssiThreshold in RegRssiThresh must be set to the sensitivity of the receiver. The
receiver will remain in WAIT mode until RssiThreshold is exceeded.
Note When AFC is enable d an d pe rf or m ed aut om a tically at th e re ce iver startup, th e ch an ne l filte r use d by the receive r
during the AFC and the AGC is RxBwAfc instead of the standard RxBw setting. This may impact the sensitivity of
the receiver, and the setting of RssiThreshold accordin gly
3.4.3.2. AGC Reference
The AGC reference level is automatically computed in the SX1231H, according to:
AGC Reference [dBm] = -174 + NF + DemodSnr +10.log(2*RxBw) + FadingMargin [dBm]
With:
NF = 7dB : LNA’s Noise Figure at maximum gain
DemodSnr = 8 dB : SNR needed by the demodulator
RxBw : Single sideband channel filter bandwidth
FadingMargin = 5 dB : Fading margin
3.4.4. Continuous-Time DAGC
In addition to the automatic gain control described in section 3.4.3, the SX1231H is capable of continuously adjusting its
gain in the digital domain, after the analog to digital conversion has occured. This feature, named DAGC, is fully
transparent to the end user. The digital gain adjustment is repeated every 2 bits, and has the following benefits:
Fully transparent to the end user
Improves the fading margin of the receiver during the reception of a packet, even if the gain of the LNA is frozen
Improves the receiver robustness in fast fading signal conditions, by quickly adjusting the receiver gain (every 2 bits)
Works in Continuous, Packet, and unlimited length Packet modes
The DAGC is enabled by setting RegTestDagc to 0x20 for low modulation index systems (i.e. when AfcLowBetaOn=1,
refer to section 3.4.16), and 0x30 for other systems. It is recommended to always enable the DAGC.
Input Power
Pin Gain
Setting Receiver Performance (typ)
P-1dB
[dBm] NF
[dB] IIP3
[dBm] IIP2
[dBm]
Pin < AgcThresh1 G1 -37 7 -18 +35
AgcThresh1 < Pin < AgcThresh2 G2 -31 13 -15 +40
AgcThresh2 < Pin < AgcThresh3 G3 -26 18 -8 +48
AgcThresh3 < Pin < AgcThresh4 G4 -14 27 -1 +62
AgcThresh4 < Pin < AgcThresh5 G5 >-6 36 +13 +68
AgcThresh5 < Pin G6 >0 44 +20 +75
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3.4.5. Quadrature Mixer - ADCs - Decimators
The mixer is inserted between output of the RF buffer stage and the input of the analog to digital converter (ADC) of the
receiver section. This block is designed to translate the spectrum of the input RF signal to base-band, and offer both high
IIP2 and IIP3 responses.
In the lower bands of operation (290 to 510 MHz), the multi-phase mixing architecture with weighted phases improves the
rejection of the LO harmonics in receiver mode, hence increasing the receiver immunity to out-of-band interferers.
The I and Q digitalization is made by two 5th order continuous-time Sigma-Delta Analog to Digital Converters (ADC). Their
gain is not constant over temperature, but the whole receiver is calibrated before reception, so that this inaccuracy has no
impact on the RSSI precision. The ADC output is one bit per channel. It needs to be decimated and filtered afterwards. This
ADC can also be used for temperature measurement, please refer to section 3.4.17 for more details.
The decimators decrease the sample rate of the incoming signal in order to optimize the area and power consumption of
the following receiver blocks.
3.4.6. Channel Filter
The role of the channel filter is to filter out the noise and interferers outside of the channel. Channel filtering on the
SX1231H is implemented with a 16-tap Finite Impulse Response (FIR) filter, providing an outstanding Adjacent Channel
Rejection performance, even for narrowband applications.
Note to respect oversampling rules in the decimation chain of the receiver, the Bit Rate cannot be set at a higher value
than 2 times the single-side receiver bandwidth (BitRate < 2 x RxBw)
The single-side channel filter bandwidth RxBw is controlled by the parameters RxBwMant and RxBwExp in RegRxBw:
When FSK modulation is enabled:
When OOK modulation is enabled:
The following channel filter bandwidths are accessible (oscillator is mandated at 32 MHz):
Table 14 Available RxBw Settings
RxBwMant
(binary/value) RxBwExp
(decimal) RxBw (kHz)
FSK
ModulationType=00 OOK
ModulationType=01
10b / 24 7 2.6 1.3
01b / 20 7 3.1 1.6
00b / 16 7 3.9 2.0
10b / 24 6 5.2 2.6
01b / 20 6 6.3 3.1
00b / 16 6 7.8 3.9
10b / 24 5 10.4 5.2
01b / 20 5 12.5 6.3
00b / 16 5 15.6 7.8
10b / 24 4 20.8 10.4
RxBw FXOSC
RxBwMant 2RxBwExp 2+
×
------------------------------------------------------------------
=
RxBw FXOSC
RxBwMant 2RxBwExp 3+
×
------------------------------------------------------------------
=
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3.4.7. DC Cancellation
DC cancellation is required in zero-IF architecture transceivers to remove any DC offset generated through self-reception.
It is built-in the SX1231 and its adjustable cutoff frequency fc is controlled in RegRxBw:
Table 15 Available DCC Cutoff Frequencies
The default value of DccFreq cutoff frequency is typically 4% of the RxBw (channel filter BW). The cutoff frequency of the
DCC can however be increased to slightly improve the sensitivity, under wider modulation conditions. It is advised to adjust
the DCC setting while monitoring the receiver sensitivity.
3.4.8. Complex Filter - OOK
In OOK mode the SX1231H is modified to a low-IF architecture. The IF frequency is automatically set to half the single side
bandwidth of the channel filter (FIF = 0.5 x RxBw). The Local Oscillator is automatically offset by the IF in the OOK receiver.
A complex filter is implemented on the chip to attenuate the resulting image frequency by typically 30 dB.
Note this filter is auto matically bypassed when receiving FSK signals (ModulationType = 00 in RegDataModul).
3.4.9. RSSI
The RSSI block evaluates the amount of energy available within the receiver channel bandwidth. Its resolution is 0.5 dB,
and it has a wide dynamic range to accommodate both small and large signal levels that may be present. Its acquisition
time is very short, taking only 2 bit periods. The RSSI sampling must occur during the reception of preamble in FSK, and
constant “1” reception in OOK.
01b / 20 4 25.0 12.5
00b / 16 4 31.3 15.6
10b / 24 3 41.7 20.8
01b / 20 3 50.0 25.0
00b / 16 3 62.5 31.3
10b / 24 2 83.3 41.7
01b / 20 2 100.0 50.0
00b / 16 2 125.0 62.5
10b / 24 1 166.7 83.3
01b / 20 1 200.0 100.0
00b / 16 1 250.0 125.0
10b / 24 0 333.3 166.7
01b / 20 0 400.0 200.0
00b / 16 0 500.0 250.0
DccFreq
in RegRxBw fc in
% of RxBw
000 16
001 8
010 (default) 4
011 2
100 1
101 0.5
110 0.25
111 0.125
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Note - RssiValue can only be read when it exceeds RssiThreshold
- The receiver is cap able of au tomatic gain calibr ation, in order to improve the precision of its RSSI measurements.
This function injects a known RF signal at the LNA input, and calibrates the receiver gain accordingly. This
calibration is automatically performed during the PLL start-up, making it a transparent process to the end-user
- RSSI accuracy depends on all components located between the ante nna port and pin RFIO, and is therefore
limited to a few dB. Board-level calibration is advised to further improve accuracy
Figure 9. RSSI Dynamic Curve
3.4.10. Cordic
The Cordic task is to extract the phase and the amplitude of the modulation vector (I+j.Q). This information, still in the
digital domain is used:
Phase output: used by the FSK demodulator and the AFC blocks.
Amplitude output: used by the RSSI block, for FSK demodulation, AGC and automatic gain calibration purposes.
Figure 10. Cordic Extraction
RSSI Chart - With AGC
-120.0
-100.0
-80.0
-60.0
-40.0
-20.0
0.0
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0
Pi n [ dBm ]
RssiValue [dBm]
I(t)
Q(t)
Real-time Phase
Real-time
Magnitude
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3.4.11. FSK Demodulator
The FSK demodulator of the SX1231H is designed to demodulate FSK, GFSK, MSK and GMSK modulated signals. It is
most efficient when the modulation index of the signal is greater than 0.5 and below 10:
The output of the FSK demodulator can be fed to the Bit Synchronizer (described in section 3.4.13), to provide the
companion processor with a synchronous data stream in Continuous mode.
3.4.12. OOK Demodulator
The OOK demodulator performs a comparison of the RSSI output and a threshold value. Three different threshold modes
are available, configured through bits OokThreshType in RegOokPeak.
The recommended mode of operation is the "Peak" threshold mode, illustrated in Figure 11:
Figure 11. OOK Peak Demodulator Description
In peak threshold mode the comparison threshold level is the peak value of the RSSI, reduced by 6dB. In the absence of
an input signal, or during the reception of a logical "0", the acquired peak value is decremented by one
OokPeakThreshStep every OokPeakThreshDec period.
When the RSSI output is null for a long time (for instance after a long string of "0" received, or if no transmitter is present),
the peak threshold level will continue falling until it reaches the "Floor Threshold", programmed in OokFixedThresh.
The default settings of the OOK demodulator lead to the performance stated in the electrical specification. However, in
applications in which sudden signal drops are awaited during a reception, the three parameters should be optimized
accordingly.
0.5 β 2FDEV
×
BR
---------------------- 10=
Zoom
Period as defined in
OokPeakThreshDec
Decay in dB as defined in
OokPeakThreshStep
Fixed 6dB difference
RSSI
[dBm]
Noise floor of
receiver
‘’Floor’’ threshold defined by
OokFixedThresh
Time
‘’Peak -6dB’’ Threshold
Zoom
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3.4.12.1. Optimizing the Floor Threshold
OokFixedThresh determines the sensitivity of the OOK receiver, as it sets the comparison threshold for weak input signals
(i.e. those close to the noise floor). Significant sensitivity improvements can be generated if configured correctly.
Note that the noise floor of the receiver at the demodulator input depends on:
The noise figure of the receiver.
The gain of the receive chain from antenna to base band.
The matching - including SAW filter if any.
The bandwidth of the channel filters.
It is therefore important to note that the setting of OokFixedThresh will be application dependant. The following procedure
is recommended to optimize OokFixedThresh.
Figure 12. Floor Threshold Optimization
The new floor threshold value found during this test should be used for OOK reception with those receiver settings.
3.4.12.2. Optimizing OOK Demodulator for Fast Fading Signals
A sudden drop in signal strength can cause the bit error rate to increase. For applications where the expected signal drop
can be estimated, the following OOK demodulator parameters OokPeakThreshStep and OokPeakThreshDec can be
optimized as described below for a given number of threshold decrements per bit. Refer to RegOokPeak to access those
settings.
3.4.12.3. Alternative OOK Demodulator Threshold Modes
In addition to the Peak OOK threshold mode, the user can alternatively select two other types of threshold detectors:
Fixed Threshold: The value is selected through OokFixedThresh
Average Threshold: Data supplied by the RSSI block is averaged, and this operation mode should only be used with
DC-free encoded data.
Set SX1231H in OOK Rx mode
Adjust Bit Rate, Channel filter BW
Default OokFixedThresh setting
No input signal
Continuous Mode
Optimization complete
Glitch activity
on DATA ?
Monitor DIO2/DATA pin
Increment
OokFixedThresh
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3.4.13. Bit Synchronizer
The Bit Synchronizer is a block that provides a clean and synchronized digital output, free of glitches. Its output is made
available on pin DIO1/DCLK in Continuous mode and can be disabled through register settings. However, for optimum
receiver performance its use when running Continuous mode is strongly advised.
The Bit Synchronizer is automatically activated in Packet mode. Its bit rate is controlled by BitRateMsb and BitRateLsb in
RegBitrate.
Figure 13. Bit Synchronizer Description
To ensure correct operation of the Bit Synchronizer, the following conditions have to be satisfied:
A preamble (0x55 or 0xAA) of 12 bits is required for synchronization (from the RxReady interrupt)
The subsequent payload bit stream must have at least one transition form '0' to '1' or '1' to '0 every 16 bits during data
transmission
The bit rate matching between the transmitter and the receiver must be better than 6.5 %.
Notes - If the Bit Rates of transmitter and receiver are known to be the same, the SX1231H will be able to receive an
infinite unbalanced sequence (all “0s” or all ”1s”) with no restriction.
- If there is a difference in Bit Rate between Tx and Rx, the amount of adjacent bits at the same level that the
BitSync can withstand can be estimated as follows:
- This implies approximately 6 consecutive unbalanced bytes when the Bit Rate precision is 1%, which is easily
achievable (crystal tolerance is in the range of 50 to 100 ppm).
3.4.14. Frequency Error Indicator
This function provides information about the frequency error of the local oscillator (LO) compared with the carrier frequency
of a modulated signal at the input of the receiver. When the FEI block is launched, the frequency error is measured and the
Raw demodulator
output
(FSK or OOK)
DCLK
DATA
BitSync Output
To pin DATA and
DCLK in continuous
mode
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signed result is loaded in FeiValue in RegFei, in 2’s complement format. The time required for an FEI evaluation is 4 times
the bit period.
To ensure a proper behavior of the FEI:
The operation must be done during the reception of preamble
The sum of the frequency offset and the 20 dB signal bandwidth must be lower than the base band filter bandwidth
The 20 dB bandwidth of the signal can be evaluated as follows (double-side bandwidth):
The frequency error, in Hz, can be calculated with the following formula:
Figure 14. FEI Process
3.4.15. Automatic Frequency Correction
The AFC is based on the FEI block, and therefore the same input signal and receiver setting conditions apply. When the
AFC procedure is done, AfcValue is directly subtracted to the register that defines the frequency of operation of the chip,
FRF
. The AFC can be launched:
Each time the receiver is enabled, if AfcAutoOn = 1
Upon user request, by setting bit AfcStart in RegAfcFei, if AfcAutoOn = 0
BW20dB 2FDEV BR
2
-------
+
⎝⎠
⎛⎞
×=
FEI FSTEP FeiValue×=
SX1239 in Rx mode
Preamble-modulated input signal
Signal level > Sensitivity
Set FeiStart
= 1
FeiDone
= 1
No
Yes
Read
FeiValue
SX1231H
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When the AFC is automatically triggered (AfcAutoOn = 1), the user has the option to:
Clear the former AFC correction value, if AfcAutoClearOn = 1
Start the AFC evaluation from the previously corrected frequency. This may be useful in systems in which the LO keeps
on drifting in the “same direction”. Ageing compensation is a good example.
The SX1231H offers an alternate receiver bandwidth setting during the AFC phase, to accommodate large LO drifts. If the
user considers that the received signal may be out of the receiver bandwidth, a higher channel filter bandwidth can be
programmed in RegAfcBw, at the expense of the receiver noise floor, which will impact upon sensitivity.
3.4.16. Optimized Setup for Low Modulation Index Systems
For wide band systems, where AFC is usually not required (XTAL inaccuracies do not typically impact the sensitivity), it
is recommended to offset the LO frequency of the receiver to avoid desensitization. This can be simply done by
modifying Frf in RegFrfLsb. A good rule of thumb is to offset the receiver’s LO by 10% of the expected transmitter
frequency deviation.
For narrow band systems, it is recommended to perform AFC. The SX1231H has a dedicated AFC, enabled when
AfcLowBetaOn in RegAfcCtrl is set to 1. A frequency offset, programmable through LowBetaAfcOffset in RegTestAfc, is
added and is calculated as follows: Offset = LowBetaAfcOffset x 488 Hz
The user should ensure that the programmed offset exceeds the DC canceller’s cutoff frequency, set through DccFreqAfc
in RegAfcBw.
Figure 15. Optimized AFC (AfcLowBetaOn=1)
As shown on Figure 15, a standard AFC sequence uses the result of the FEI to correct the LO frequency and align both
local oscillators. When the optimized AFC is enabled (AfcLowBetaOn=1), the receiver’s LO is corrected by “FeiValue +
LowBetaAfcOffset”.
When the optimized AFC routine is enabled, the receiver startup time can be computed as follows (refer to section 4.2.3):
TS_RE_AGC&AFC (optimized AFC) = Tana + 4.Tcf + 4.Tdcc + 3.Trssi + 2.Tafc + 2.Tpllafc
f
TXRX
f
RX &TX
Standard AFC
AfcLowBetaOn = 0
f
TXRX TX RX
LowBetaAfcOffset
f
AfcValue
AfcValue
FeiValue
FeiValue Optimized AFC
AfcLowBetaOn = 1
Before AFC After AFC
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3.4.17. Temperature Sensor
When temperature is measured, the receiver ADC is used to digitize the sensor response. Most receiver blocks are
disabled, and temperature measurement can only be triggered in Standby or Frequency Synthesizer modes.
The response of the temperature sensor is -1°C / Lsb. A CMOS temperature sensor is not accurate by nature, therefore it
should be calibrated at ambient temperature for precise temperature readings.
Figure 16. Temperature Sensor Response
It takes less than 100 microseconds for the SX1231H to evaluate the temperature (from setting TempMeasStart to 1 to
TempMeasRunning reset).
3.4.18. Timeout Function
The SX1231H includes a Timeout function, which allows it to automatically shut-down the receiver after a receive
sequence and therefore save energy.
Timeout interrupt is generated TimeoutRxStart x 16x Tbit after switching to RX mode if RssiThreshold flag does not
raise within this time frame
Timeout interrupt is generated TimeoutRssiThresh x 16 x Tbit after RssiThreshold flag has been raised.
This timeout interrupt can be used to warn the companion processor to shut down the receiver and return to a lower power
mode.
-40°C+85°C
TempValue
Ambient
Returns 150d (typ.)
Needs calibration
tt+1
TempValue(t)
TempValue(t)-1
-1°C/Lsb
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4. Operating Modes
4.1. Basic Modes
The circuit can be set in 5 different basic modes which are described in Table 16.
By default, when switching from a mode to another one, the sub-blocks are woken up according to a pre-defined and
optimized sequence. Alternatively, these operating modes can be selected directly by disabling the automatic sequencer
(SequencerOff in RegOpMode = 1).
Table 16 Basic Transceiver Modes
4.2. Automatic Sequencer and Wake-Up Times
By default, when switching from one operating mode to another, the circuit takes care of the sequence of events in such a
way that the transition timing is optimized. For example, when switching from Sleep mode to Transmit mode, the SX1231H
goes first to Standby mode (XO started), then to frequency synthesizer mode, and finally, when the PLL has locked, to
transmit mode. Entering transmit mode is also made according to a predefined sequence starting with the wake-up of the
PA regulator before applying a ramp-up on the PA and generating the DCLK clock.
The crystal oscillator wake-up time, TS_OSC, is directly related to the time for the crystal oscillator to reach its steady
state. It depends notably on the crystal characteristics.
The frequency synthesizer wake-up time, TS_FS, is directly related to the time needed by the PLL to reach its steady
state. The signal PLL_LOCK, provided on an external pin, gives an indication of the lock status. It goes high when the
PLL reaches its locking range.
Four specific cases can be highlighted:
Transmitter Wake Up time from Sleep mode = TS_OSC + TS_FS + TS_TR
Receiver Wake Up time from Sleep mode = TS_OSC + TS_FS + TS_RE
Receiver Wake Up time from Sleep mode, AGC enabled = TS_OSC + TS_FS + TS_RE_AGC
Receiver Wake Up time from Sleep mode, AGC and AFC enabled = TS_OSC + TS_FS + TS_RE_AGC&AFC
These timings are detailed in sections 4.2.1 and 4.2.3.
In applications where the target average power consumption, or the target startup time, do not require setting the SX1231H
in the lowest power modes (Sleep or Standby), the respective timings TS_OSC and TS_FS in the former equations can be
omitted.
ListenOn
in RegOpMode Mode
in RegOpMode Selected mode Enabled bl ocks
0 0 0 0 Sleep Mode None
0 0 0 1 Stand-by Mode Top regulator and crystal oscillator
0 0 1 0 FS Mode Frequency synthesizer
0 0 1 1 Transmit Mode Frequency synthesizer and transmitter
0 1 0 0 Receive Mode Frequency synthesizer and receiver
1 x Listen Mode See Listen Mode, section 4.3
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4.2.1. Transmitter Startup Time
The transmitter wake-up time, TS_TR, is given by the sequence controlled by the digital part. It is a pure digital delay which
depends on the bit rate and the ramp-up time. In FSK mode, this time can be derived from the following equation.
,
where PaRamp is the ramp-up time programmed in RegPaRamp and Tbit is the bit time.
In OOK mode, this equation can be simplified to the following:
Figure 17. Tx Startup, FSK and OOK
4.2.2. Tx Start Procedure
As described in the former section, ModeReady and TxReady interrupts warn the uC that the transmitter is ready to
transmit data
In Continuous mode, the preamble bits preceding the payload can be applied on the DIO2/DATA pin immediately after
any of these interrupts have fired. The DCLK signal, activated on pin DIO1/DCLK can also be used to start toggling the
DATA pin, as described on Figure 30.
In Packet mode, the SX1231H will automatically modulate the RF signal with preamble bytes as soon as TxReady or
ModeReady happen. The actual packet transmission (starting with the number of preambles specified in PreambleSize)
will start when the TxStartCondition is fulfilled.
4.2.3. Receiver Startup Time
It is highly recommended to use the built-in sequencer of the SX1231H, to optimize the delays when setting the chip in
receive mode. It guarantees the shortest startup times, hence the lowest possible energy usage, for battery operated
systems.
The startup times of the receiver can be calculated from the following:
TbitPaRampsTRTS ×+×+=
2
1
25.15_
μ
TbitsTRTS ×+=
2
1
5_
μ
Analog
group delay 0.5 x Tbit
1.25 x PaRamp
(only in FSK
mode)
XO Started and PLL is locked
5 us
Transmission of Packet
ModeReady
TxReady
TS_TR
Tx startup request
(sequencer or user)
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Figure 18. Rx Startup - No AGC, no AFC
Figure 19. Rx Startup - AGC, no AFC
Figure 20. Rx Startup - AGC and AFC
The different timings shown above are as follows:
Group delay of the analog front end: Tana = 20 us
Channel filter’s group delay in FSK mode: Tcf = 21 / (4.RxBw)
Channel filter’s group delay in OOK mode: Tcf = 34 / (4.RxBw)
DC Cutoff’s group delay: Tdcc = max(8 , 2^(round(log2(8.RxBw.Tbit)+1)) / (4.RxBw)
PLL lock time after AFC adjustment: Tpllafc = 5 / PLLBW (PLLBW = 300 kHz)
AFC sample time: Tafc = 4 x Tbit (also denoted TS_AFC in the general specification)
RSSI sample time: Trssi = 2 x int(4.RxBw.Tbit)/(4.RxBw) (aka TS_RSSI)
Note The above timings represent maximum settling time s, and shorter settling times may be observed in real cases
Analog FE’s
group delay
Channel Filter’s
group delay
DC Cutoff’s
group delay
RSSI
sampling
XO Started and PLL is locked
Tana
RSSI
sampling
Tcf Tdcc Trssi Trssi
Reception of Packet
ModeReady
RxReady
TS_RE
Rx startup request
(sequencer or user)
Received Packet Preamble may start
Analog FE’s
group delay
Channel Filter’s
group delay
DC Cutoff’s
group delay
RSSI
sampling
XO Started and PLL is locked
Tana
RSSI
sampling
Tcf Tdcc Trssi Trssi
Reception of Packet
ModeReady
RxReady
Channel Filter’s
group delay
DC Cutoff’s
group delay
RSSI
sampling
Tcf Tdcc Trssi
The LNA gain is adjusted by
the AGC, according to the
RSSI result
TS_RE_AGC
Rx startup request
(sequencer or user)
Received Packet Preamble may start
Analog FE’s
group delay
Channel Filter’s
group delay
DC Cutoff’s
group delay
RSSI
sampling
XO Started and
PLL is locked
Tana
RSSI
sampling
Tcf Tdcc Trssi Trssi
Reception of Packet
ModeReady
RxReady
Channel Filter’s
group delay
DC Cutoff’s
group delay
RSSI
sampling
Tcf Tdcc Trssi
AFC
Tafc
PLL
lock
Tpllafc
Channel Filter’s
group delay
Tcf
DC Cutoff’s
group delay
Tdcc
TS_RE_AGC&AFC
Rx startup request
(sequencer or user)
The LNA gain is adjusted by
the AGC, according to the
RSSI result
Carrier Frequency is adjusted
by the AFC
Received Packet Preamble may start
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4.2.4. Rx Start Procedure
As described in the former sections, the RxReady interrupt warns the uC that the receiver is ready.
In Continuous mode with Bit Synchronizer, the receiver will start locking its Bit Synchronizer on a minimum or 12 bits of
received preamble (see section 3.4.13 for details), before the reception of correct Data, or Sync Word (if enabled) can
occur.
In Continuous mode without Bit Synchronizer, valid data will be available on DIO2/DATA right after the RxReady
interrupt.
In Packet mode, the receiver will start locking its Bit Synchronizer on a minimum or 12 bits of received preamble (see
section 3.4.13 for details), before the reception of correct Data, or Sync Word (if enabled) can occur.
4.2.5. Optimized Frequency Hopping Sequences
In a frequency hopping-like application, it is required to turn off the transmitter when hopping from one channel to another,
to avoid spectral splatter and obtain the best spectral purity.
Transmitter hop from Ch A to Ch B: it is advised to step through the Rx mode:
(0) SX1231H is in Tx mode in Ch A
(1) Program the SX1231H in Rx mode
(2) Change the carrier frequency in the RegFrf registers
(3) Turn the transceiver back to Tx mode
(4) Respect the Tx start procedure, described in section 4.2.2
Receiver hop from Ch A to Ch B:
(0) SX1231H is in Rx mode in Ch A
(1) Change the carrier frequency in the RegFrf registers
(2) Program the SX1231H in FS mode
(3) Turn the transceiver back to Rx mode
(4) Respect the Rx start procedure, described in section 4.2.4
Note all sequences described above are assuming that the sequencer is turned on (SequencerOff=0 in RegOpMode).
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4.3. Listen Mode
The circuit can be set to Listen mode, by setting ListenOn in RegOpMode to 1 while in Standby mode. In this mode,
SX1231H spends most of the time in Idle mode, during which only the RC oscillator runs. Periodically the receiver is woken
up and listens for an RF signal. If a wanted signal is detected, the receiver is kept on and the data is demodulated.
Otherwise, if a wanted signal hasn't been detected after a pre-defined period of time, the receiver is disabled until the next
time period.
This periodical Rx wake-up requirement is very common in low power applications. On SX1231H it is handled locally by the
Listen mode block without using uC resources or energy.
The simplified timing diagram of this procedure is illustrated in Figure 21.
Figure 21. Listen Mode Sequence (no wanted signal is received)
4.3.1. Timings
The duration of the Idle phase is given by tListenIdle. The time during which the receiver is on and waits for a signal is given
by tListenRx. tListenRx includes the wake-up time of the receiver, described in section 4.2.3. This duration can be
programmed in the configuration registers via the serial interface.
Both time periods tListenRx and tListenIdle (denoted tListenX in the following text) are fixed by two parameters from the
configuration register and are calculated as follows:
where ListenResolX is the Rx or Idle resolution and is independently programmable on three values (64us, 4.1ms or
262ms), whereas ListenCoefX is an integer between 1 and 255. All parameters are located in RegListen registers.
The timing ranges are tabulated in Table 17 below.
Table 17 Range of Durations in Listen Mode
ListenResolX Min duration
( ListenCoef = 1 ) Max duration
( ListenCoef = 255 )
01 64 us 16 ms
10 4.1 ms 1.04 s
11 0.26 s 67 s
time
tListenIdle
tListenRx tListenRx
Idle
Rx Rx
solXListenXListenCoeftListenX Re=
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Notes - the accuracy of the typical timings given in Table 17 will depend in the RC oscillator calibration
- RC oscillator calibration is required, and must be performed at power up. See section 4.3.5 for details
4.3.2. Criteria
The criteria taken for detecting a wanted signal and hence deciding to maintain the receiver on is defined by ListenCriteria
in RegListen1.
Table 18 Signal Acceptance Criteria in Listen Mode
4.3.3. End of Cycle Actions
The action taken after detection of a packet, is defined by ListenEnd in RegListen3, as described in the table below.
Table 19 End of Listen Cycle Actions
ListenCriteria Input Signal Power
>= RssiThreshold SyncAddressMatch
0 Required Not Required
1 Required Required
ListenEnd Description
00 Chip stays in Rx mode. Listen mode stops and must be disabled.
01 Chip stays in Rx mode until PayloadReady or Timeout interrupt occurs. It then goes to the
mode defined by Mode. Listen mode stops and must be disabled.
10 Chip stays in Rx mode until PayloadReady or Timeout interrupt occurs. Listen mode then
resumes in Idle state. FIFO content is lost at next Rx wakeup.
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Upon detection of a valid packet, the sequencing is altered, as shown below:
Figure 22. Listen Mode Sequence (wanted signal is received)
4.3.4. Stopping Listen Mode
To abort Listen mode operation, the following procedure must be respected:
Program RegOpMode with ListenOn=0, ListenAbort=1, and the desired setting for the Mode bits (Sleep, Stdby, FS, Rx
or Tx mode) in a single SPI access
Program RegOpMode with ListenOn=0, ListenAbort=0, and the desired setting for the Mode bits (Sleep, Stdby, FS, Rx
or Tx mode) in a second SPI access
4.3.5. RC Timer Accuracy
All timings of the Listen Mode rely on the accuracy of the internal low-power RC oscillator. This oscillator is automatically
calibrated at the device power-up, and it is a user-transparent process.
For applications enduring large temperature variations, and for which the power supply is never removed, RC calibration
can be performed upon user request. RcCalStart in RegOsc1 can be used to trigger this calibration, and the flag
RcCalDone will be set automatically when the calibration is over.
PayloadReady
ListenCriteria
passed
Listen Mode
Idle Rx
Listen Mode
Listen Mode
Idle Rx Mode
Idle Rx Idle Rx
ListenEnd = 00
ListenEnd = 01
ListenEnd = 10
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4.4. AutoModes
Automatic modes of packet handler can be enabled by configuring the related parameters in RegAutoModes.
The intermediate mode of the chip is called IntermediateMode and the enter and exit conditions to/from this intermediate
mode can be configured through the parameters EnterCondition & ExitCondition.
The enter and exit conditions cannot be used independently of each other i.e. both should be enabled at the same time.
The initial and the final state is the one configured in Mode in RegOpMode. The initial & final states can be different by
configuring the modes register while the chip is in intermediate mode. The pictorial description of the auto modes is shown
below.
Figure 23. Auto Modes of Packet Handler
Some typical examples of AutoModes usage are described below:
Automatic transmission (AutoTx) : Mode = Sleep, IntermediateMode = Tx, EnterCondition = FifoLevel, ExitCondition =
PacketSent
Automatic reception (AutoRx) : Mode = Rx, IntermediateMode = Sleep, EnterCondition = CrcOk, ExitCondition = falling
edge of FifoNotEmpty
Automatic reception of acknowledge (AutoRxAck): Mode = Tx, IntermediateMode = Rx, EnterCondition = PacketSent,
ExitCondition = CrcOk
...
Initial state defined
By Mode in RegOpMode
Intermediate State
defined by IntermediateMode
ExitCondition
EnterCondition
Final state defined
By Mode in RegOpMode
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5. Data Processing
5.1. Overview
5.1.1. Block Diagram
Figure below illustrates the SX1231H data processing circuit. Its role is to interface the data to/from the modulator/
demodulator and the uC access points (SPI and DIO pins). It also controls all the configuration registers.
The circuit contains several control blocks which are described in the following paragraphs.
Figure 24. SX1231H Data Processing Conceptual View
The SX1231H implements several data operation modes, each with their own data path through the data processing
section. Depending on the data operation mode selected, some control blocks are active whilst others remain disabled.
5.1.2. Data Operation Modes
The SX1231H has two different data operation modes selectable by the user:
Continuous mode: each bit transmitted or received is accessed in real time at the DIO2/DATA pin. This mode may be
used if adequate external signal processing is available.
Packet mode (recommended): user only provides/retrieves payload bytes to/from the FIFO. The packet is automatically
built with preamble, Sync word, and optional AES, CRC, and DC-free encoding schemes The reverse operation is
performed in reception. The uC processing overhead is hence significantly reduced compared to Continuous mode.
Depending on the optional features activated (CRC, AES, etc) the maximum payload length is limited to FIFO size, 255
bytes or unlimited.
Each of these data operation modes is described fully in the following sections.
CONTROL
SPI
PACKET
HANDLER
SYNC
RECOG.
DIO1
MISO
MOSI
SCK
NSS
Rx
Tx
Tx/Rx
Data
FIFO
(+SR)
Potential datapaths (data operation mode dependant)
DIO2
DIO0
DIO3
DIO4
DIO5
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5.2. Control Block Description
5.2.1. SPI Interface
The SPI interface gives access to the configuration register via a synchronous full-duplex protocol corresponding to CPOL
= 0 and CPHA = 0 in Motorola/Freescale nomenclature. Only the slave side is implemented.
Three access modes to the registers are provided:
SINGLE access: an address byte followed by a data byte is sent for a write access whereas an address byte is sent and
a read byte is received for the read access. The NSS pin goes low at the begin of the frame and goes high after the data
byte.
BURST access: the address byte is followed by several data bytes. The address is automatically incremented internally
between each data byte. This mode is available for both read and write accesses. The NSS pin goes low at the
beginning of the frame and stay low between each byte. It goes high only after the last byte transfer.
FIFO access: if the address byte corresponds to the address of the FIFO, then succeeding data byte will address the
FIFO. The address is not automatically incremented but is memorized and does not need to be sent between each data
byte. The NSS pin goes low at the beginning of the frame and stay low between each byte. It goes high only after the
last byte transfer.
Figure below shows a typical SPI single access to a register.
Figure 25. SPI Timing Diagram (single access)
MOSI is generated by the master on the falling edge of SCK and is sampled by the slave (i.e. this SPI interface) on the
rising edge of SCK. MISO is generated by the slave on the falling edge of SCK.
A transfer always starts by the NSS pin going low. MISO is high impedance when NSS is high.
The first byte is the address byte. It is made of:
wnr bit, which is 1 for write access and 0 for read access
7 bits of address, MSB first
The second byte is a data byte, either sent on MOSI by the master in case of a write access, or received by the master on
MISO in case of read access. The data byte is transmitted MSB first.
Proceeding bytes may be sent on MOSI (for write access) or received on MISO (for read access) without rising NSS and
re-sending the address. In FIFO mode, if the address was the FIFO address then the bytes will be written / read at the
FIFO address. In Burst mode, if the address was not the FIFO address, then it is automatically incremented at each new
byte received.
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The frame ends when NSS goes high. The next frame must start with an address byte. The SINGLE access mode is
actually a special case of FIFO / BURST mode with only 1 data byte transferred.
During the write access, the byte transferred from the slave to the master on the MISO line is the value of the written
register before the write operation.
5.2.2. FIFO
5.2.2.1. Overview and Shift Register (SR)
In packet mode of operation, both data to be transmitted and that has been received are stored in a configurable FIFO
(First In First Out) device. It is accessed via the SPI interface and provides several interrupts for transfer management.
The FIFO is 1 byte wide hence it only performs byte (parallel) operations, whereas the demodulator functions serially. A
shift register is therefore employed to interface the two devices. In transmit mode it takes bytes from the FIFO and outputs
them serially (MSB first) at the programmed bit rate to the modulator. Similarly, in Rx the shift register gets bit by bit data
from the demodulator and writes them byte by byte to the FIFO. This is illustrated in figure below.
Figure 26. FIFO and Shift Register (SR)
Note When switching to Sleep mode, the FIFO can only be used once th e ModeReady flag is set (quasi immediate from
all modes except from Tx)
5.2.2.2. Size
The FIFO size is fixed to 66 bytes.
5.2.2.3. Interrupt Sources and Flags
FifoNotEmpty: FifoNotEmpty interrupt source is low when byte 0, i.e. whole FIFO, is empty. Otherwise it is high. Note
that when retrieving data from the FIFO, FifoNotEmpty is updated on NSS falling edge, i.e. when FifoNotEmpty is
updated to low state the currently started read operation must be completed. In other words, FifoNotEmpty state must
be checked after each read operation for a decision on the next one (FifoNotEmpty = 1: more byte(s) to read;
FifoNotEmpty = 0: no more byte to read).
FifoFull: FifoFull interrupt source is high when the last FIFO byte, i.e. the whole FIFO, is full. Otherwise it is low.
FifoOverrunFlag: FifoOverrunFlag is set when a new byte is written by the user (in Tx or Standby modes) or the SR (in
Rx mode) while the FIFO is already full. Data is lost and the flag should be cleared by writing a 1, note that the FIFO will
also be cleared.
PacketSent: PacketSent interrupt source goes high when the SR's last bit has been sent.
FifoLevel: Threshold can be programmed by FifoThreshold in RegFifoThresh. Its behavior is illustrated in figure below.
Data Tx/Rx 8
1
SR (8bits)
byte0
byte1 FIFO
MSB LSB
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Figure 27. FifoLevel IRQ Source Behavior
Note - FifoLevel interrupt is updated only after a read or write operation on the FIFO. Th us the interrupt cannot be
dynamically updated by only changing the FifoThreshold parameter
- FifoLevel interrupt is valid as long as FifoFull does not occur. An empty FIFO will restore its normal operation
5.2.2.4. FIFO Clearing
Table below summarizes the status of the FIFO when switching between different modes
Table 20 Status of FIFO when Switching Between Different Modes of the Chip
5.2.3. Sync Word Recognition
5.2.3.1. Overview
Sync word recognition (also called Pattern recognition) is activated by setting SyncOn in RegSyncConfig. The bit
synchronizer must also be activated in continuous mode (automatically done in Packet mode) .
The block behaves like a shift register; it continuously compares the incoming data with its internally programmed Sync
word and sets SyncAddressMatch when a match is detected. This is illustrated in Figure 28 below.
From To FIFO status Comments
Stdby Sleep Not cleared
Sleep Stdby Not cleared
Stdby/Sleep Tx Not cleared To allow the user to write the FIFO in Stdby/Sleep before Tx
Stdby/Sleep Rx Cleared
Rx Tx Cleared
Rx Stdby/Sleep Not cleared To allow the user to read FIFO in Stdby/Sleep mode after Rx
Tx Any Cleared
# of bytes in FIFO
FifoLevel
0
1
BB+1
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Figure 28. Sync Word Recognition
During the comparison of the demodulated data, the first bit received is compared with bit 7 (MSB) of RegSyncValue1 and
the last bit received is compared with bit 0 (LSB) of the last byte whose address is determined by the length of the Sync
word.
When the programmed Sync word is detected the user can assume that this incoming packet is for the node and can be
processed accordingly.
SyncAddressMatch is cleared when leaving Rx or FIFO is emptied.
5.2.3.2. Configuration
Size: Sync word size can be set from 1 to 8 bytes (i.e. 8 to 64 bits) via SyncSize in RegSyncConfig. In Packet mode this
field is also used for Sync word generation in Tx mode.
Error tolerance: The number of errors tolerated in the Sync word recognition can be set from 0 to 7 bits to via SyncTol.
Value: The Sync word value is configured in SyncValue(63:0). In Packet mode this field is also used for Sync word
generation in Tx mode.
Note SyncValue choices containing 0x00 bytes are no t allo we d
5.2.4. Packet Handler
The packet handler is the block used in Packet mode. Its functionality is fully described in section 5.5.
5.2.5. Control
The control block configures and controls the full chip's behavior according to the settings programmed in the configuration
registers.
5.3. Digital IO Pins Mapping
Six general purpose IO pins are available on the SX1231H, and their configuration in Continuous or Packet mode is
controlled through RegDioMapping1 and RegDioMapping2.
Rx DATA
(NRZ)
DCLK
Bit N-x =
Sync_value[x]
Bit N-1 =
Sync_value[1]
Bit N =
Sync_value[0]
SyncAddressMatch
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5.3.1. DIO Pins Mapping in Continuous Mode
Table 21 DIO Mapping, Continuous Mode
5.3.2. DIO Pins Mapping in Packet Mode
Table 22 DIO Mapping, Packet Mode
Note Received Data is only shown on the Data signal between RxReady and PayloadReady’s rising edges
Mode Diox
Mapping DIO5 DIO4 DIO3 DIO2 DIO1 DIO0
00------
01------
10 - - AutoMode - - -
11 ModeReady - - - - ModeReady
00 ClkOut - - - - -
01------
10 - - AutoMode - - -
11 ModeReady - - - - ModeReady
00 ClkOut - - - - PllLock
01------
10 - - AutoMode - - -
11 ModeReady PllLock - - PllLock ModeReady
00 ClkOut Timeout Rssi Data Dclk SyncAddress
01 Rssi RxReady RxReady Data RxReady Timeout
10 - SyncAddress AutoMode Data - Rssi
11 ModeReady PllLock Timeout Data SyncAddress ModeReady
00 ClkOut TxReady TxReady Data Dclk PllLock
01 ClkOut TxReady TxReady Data TxReady TxReady
10 - - AutoMode Data - -
11 ModeReady PllLock TxReady Data PllLock ModeReady
Tx
FS
Rx
Sleep
Stdby
Mode Diox
Mapping DIO5 DIO4 DIO3 DIO2 DIO1 DIO0
00 - - FifoFull FifoNotEmpty FifoLevel -
01 - - - - FifoFull -
10 - - - - FifoNotEmpty -
11 ModeReady - - AutoMode - -
00 ClkOut - FifoFull FifoNotEmpty FifoLevel -
01 - - - - FifoFull -
10 - - - - FifoNotEmpty -
11 ModeReady - - AutoMode - -
00 ClkOut - FifoFull FifoNotEmpty FifoLevel -
01 - - - - FifoFull -
10 - - - - FifoNotEmpty -
11 ModeReady PllLock PllLock AutoMode PllLock PllLock
00 ClkOut Timeout FifoFull FifoNotEmpty FifoLevel CrcOk
01 Data Rssi Rssi Data FifoFull PayloadReady
10 - RxReady SyncAddress - FifoNotEmpty SyncAddress
11 ModeReady PllLock PllLock AutoMode Timeout Rssi
00 ClkOut ModeReady FifoFull FifoNotEmpty FifoLevel PacketSent
01 Data TxReady TxReady Data FifoFull TxReady
10 - - - - FifoNotEmpty -
11 ModeReady PllLock PllLock AutoMode PllLock PllLock
Tx
FS
Rx
Sleep
Stdby
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5.4. Continuous Mode
5.4.1. General Description
As illustrated in Figure 29, in Continuous mode the NRZ data to (from) the (de)modulator is directly accessed by the uC on
the bidirectional DIO2/DATA pin. The FIFO and packet handler are thus inactive.
Figure 29. Continuous Mode Conceptual View
5.4.2. Tx Processing
In Tx mode, a synchronous data clock for an external uC is provided on DIO1/DCLK pin. Clock timing with respect to the
data is illustrated in Figure 30. DATA is internally sampled on the rising edge of DCLK so the uC can change logic state
anytime outside the grayed out setup/hold zone.
Figure 30. Tx Processing in Continuous Mode
Note the use of DCLK is required when the modulation shaping is enabled (see section 3.3.5).
CONTROL
SPI
SYNC
RECOG.
DIO1/DCLK
MISO
MOSI
SCK
NSS
Rx
Tx/Rx
Data
DIO2/DATA
DIO0
DIO3
DIO4
DIO5
DCLK
T_DATAT_DATA
DATA
(NRZ)
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5.4.3. Rx Processing
If the bit synchronizer is disabled, the raw demodulator output is made directly available on DATA pin and no DCLK signal
is provided.
Conversely, if the bit synchronizer is enabled, synchronous cleaned data and clock are made available respectively on
DIO2/DATA and DIO1/DCLK pins. DATA is sampled on the rising edge of DCLK and updated on the falling edge as
illustrated below.
Figure 31. Rx Processing in Continuous Mode
Note in Continuous mode it is always recommended to enable the bit synchro nizer to clean the DATA signal even if the
DCLK signal is not used by the uC (bit synchronizer is automatically enabled in Packet mode).
5.5. Packet Mode
5.5.1. General Description
In Packet mode the NRZ data to (from) the (de)modulator is not directly accessed by the uC but stored in the FIFO and
accessed via the SPI interface.
In addition, the SX1231H packet handler performs several packet oriented tasks such as Preamble and Sync word
generation, CRC calculation/check, whitening/dewhitening of data, Manchester encoding/decoding, address filtering, AES
encryption/decryption, etc. This simplifies software and reduces uC overhead by performing these repetitive tasks within
the RF chip itself.
Another important feature is ability to fill and empty the FIFO in Sleep/Stdby mode, ensuring optimum power consumption
and adding more flexibility for the software.
DATA (NRZ)
DCLK
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Figure 32. Packet Mode Conceptual View
Note The Bit Synchronizer is automatically enabled in Packet mode.
5.5.2. Packet Format
5.5.2.1. Fixed Length Packet Format
Fixed length packet format is selected when bit PacketFormat is set to 0 and PayloadLength is set to any value greater
than 0.
In applications where the packet length is fixed in advance, this mode of operation may be of interest to minimize RF
overhead (no length byte field is required). All nodes, whether Tx only, Rx only, or Tx/Rx should be programmed with the
same packet length value.
The length of the payload is limited to 255 bytes if AES is not enabled else the message is limited to 64 bytes (i.e. max 65
bytes payload if Address byte is enabled).
The length programmed in PayloadLength relates only to the payload which includes the message and the optional
address byte. In this mode, the payload must contain at least one byte, i.e. address or message byte.
An illustration of a fixed length packet is shown below. It contains the following fields:
Preamble (1010...)
Sync word (Network ID)
Optional Address byte (Node ID)
Message data
Optional 2-bytes CRC checksum
CONTROL
SPI
PACKET
HANDLER
SYNC
RECOG.
DIO1
MISO
MOSI
SCK
NSS
Rx
Tx
Data
FIFO
(+SR)
DIO2
DIO0
DIO3
DIO4
DIO5
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Figure 33. Fixed Length Packet Format
5.5.2.2. Variable Length Packet Format
Variable length packet format is selected when bit PacketFormat is set to 1.
This mode is useful in applications where the length of the packet is not known in advance and can vary over time. It is then
necessary for the transmitter to send the length information together with each packet in order for the receiver to operate
properly.
In this mode the length of the payload, indicated by the length byte, is given by the first byte of the FIFO and is limited to
255 bytes if AES is not enabled else the message is limited to 64 bytes (i.e. max 66 bytes payload if Address byte is
enabled). Note that the length byte itself is not included in its calculation. In this mode, the payload must contain at least 2
bytes, i.e. length + address or message byte.
An illustration of a variable length packet is shown below. It contains the following fields:
Preamble (1010...)
Sync word (Network ID)
Length byte
Optional Address byte (Node ID)
Message data
Optional 2-bytes CRC checksum
Figure 34. Variable Length Packet Format
Message
Up to 255 bytes
Address
byte
CRC
2-bytes
Sync Word
0 to 8 bytes
Preamble
0 to 65535
bytes
Payload
(min 1 byte)
CRC checksum calculation
DC free Data encoding
Fields added by the packet handler in Tx and processed and removed in Rx
Optional User provided fields which are part of the payload
Message part of the payload
AES Enc/Dec
Message
Up to 255 bytes
Address
byte
Length
byte
CRC
2-bytes
Sync Word
0 to 8 bytes
Preamble
0 to 65535
bytes
Payload
(min 2 bytes)
CRC checksum calculation
DC free Data encoding
Fields added by the packet handler in Tx and processed and removed in Rx
Optional User provided fields which are part of the payload
Message part of the payload
AES Enc/Dec
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5.5.2.3. Unlimited Length Packet Format
Unlimited length packet format is selected when bit PacketFormat is set to 0 and PayloadLength is set to 0.
The user can then transmit and receive packet of arbitrary length and PayloadLength register is not used in Tx/Rx modes
for counting the length of the bytes transmitted/received. This mode is a replacement for the legacy buffered mode in
SX1211/SX1212 transceivers.
In Tx the data is transmitted depending on the TxStartCondition bit. On the Rx side the data processing features like
Address filtering, Manchester encoding and data whitening are not available if the sync pattern length is set to zero
(SyncOn = 0). The filling of the FIFO in this case can be controlled by the bit FifoFillCondition. The CRC detection in Rx is
also not supported in this mode of the packet handler, however CRC generation in Tx is operational. The interrupts like
CrcOk & PayloadReady are not available either.
An unlimited length packet shown in is made up of the following fields:
Preamble (1010...).
Sync word (Network ID).
Optional Address byte (Node ID).
Message data
Optional 2-bytes CRC checksum (Tx only)
Figure 35. Unlimited Length Packet Format
5.5.3. Tx Processing (without AES)
In Tx mode the packet handler dynamically builds the packet by performing the following operations on the payload
available in the FIFO:
Add a programmable number of preamble bytes
Add a programmable Sync word
Optionally calculating CRC over complete payload field (optional length byte + optional address byte + message) and
appending the 2 bytes checksum.
Optional DC-free encoding of the data (Manchester or whitening)
Only the payload (including optional address and length fields) is required to be provided by the user in the FIFO.
Message
unlimited length
Address
byte
Sync Word
0 to 8 bytes
Preamble
0 to 65535
bytes
Payload
Fields added by the packet handler in Tx and processed and removed in Rx
Optional User provided fields which are part of the payload
Message part of the payload
DC free Data encoding
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The transmission of packet data is initiated by the Packet Handler only if the chip is in Tx mode and the transmission
condition defined by TxStartCondition is fulfilled. If transmission condition is not fulfilled then the packet handler transmits a
preamble sequence until the condition is met. This happens only if the preamble length /= 0, otherwise it transmits a zero or
one until the condition is met to transmit the packet data.
The transmission condition itself is defined as:
if TxStartCondition = 1, the packet handler waits until the first byte is written into the FIFO, then it starts sending the
preamble followed by the sync word and user payload
If TxStartCondition = 0, the packet handler waits until the number of bytes written in the FIFO is equal to the number
defined in RegFifoThresh + 1
If the condition for transmission was already fulfilled i.e. the FIFO was filled in Sleep/Stdby then the transmission of
packet starts immediately on enabling Tx
5.5.4. Rx Processing (without AES)
In Rx mode the packet handler extracts the user payload to the FIFO by performing the following operations:
Receiving the preamble and stripping it off
Detecting the Sync word and stripping it off
Optional DC-free decoding of data
Optionally checking the address byte
Optionally checking CRC and reflecting the result on CrcOk.
Only the payload (including optional address and length fields) is made available in the FIFO.
When the Rx mode is enabled the demodulator receives the preamble followed by the detection of sync word. If fixed
length packet format is enabled then the number of bytes received as the payload is given by the PayloadLength
parameter.
In variable length mode the first byte received after the sync word is interpreted as the length of the received packet. The
internal length counter is initialized to this received length. The PayloadLength register is set to a value which is greater
than the maximum expected length of the received packet. If the received length is greater than the maximum length stored
in PayloadLength register the packet is discarded otherwise the complete packet is received.
If the address check is enabled then the second byte received in case of variable length and first byte in case of fixed
length is the address byte. If the address matches to the one in the NodeAddress field, reception of the data continues
otherwise it's stopped. The CRC check is performed if CrcOn = 1 and the result is available in CrcOk indicating that the
CRC was successful. An interrupt (PayloadReady) is also generated on DIO0 as soon as the payload is available in the
FIFO. The payload available in the FIFO can also be read in Sleep/Standby mode.
If the CRC fails the PayloadReady interrupt is not generated and the FIFO is cleared. This function can be overridden by
setting CrcAutoClearOff = 1, forcing the availability of PayloadReady interrupt and the payload in the FIFO even if the CRC
fails.
5.5.5. AES
AES is the symmetric-key block cipher that provides the cryptographic capabilities to the transceiver. The system proposed
can work with 128-bit long fixed keys. The fixed key is stored in a 16-byte write only user configuration register, which
retains its value in Sleep mode.
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As shown in Figure 33 and Figure 34 above the message part of the Packet can be encrypted and decrypted with the
cipher 128- cipher key stored in the configuration registers.
5.5.5.1. Tx Processing
1. User enters the data to be transmitted in FIFO in Stdby/Sleep mode and gives the transmit command.
2. On Tx command the Packet handler state machine takes over the control and If encryption is enabled then the
message inside the FIFO is read in blocks of 16 bytes (padded with 0s if needed), encrypted and stored back to FIFO.
All this processing is done in Tx mode before enabling the packet handling state machine. Only the Message part of the
packet is encrypted and preamble, sync word, length byte, address byte and CRC are not encrypted.
3. Once the encryption is done the Packet handling state machine is enabled to transmit the data.
5.5.5.2. Rx Processing
1. The data received is stored in the FIFO, The address, CRC interrupts are generated as usual because these
parameters were not encrypted.
2. Once the complete packet has been received. The data is read from the FIFO, decrypted and written back to FIFO.
The PayloadReady interrupt is issued once the decrypted data is ready in the FIFO for reading via the SPI interface.
The AES encryption/decryption cannot be used on the fly i.e. while transmitting and receiving data. Thus when AES
encryption/decryption is enabled, the FIFO acts as a simple buffer. This buffer is filled before initiating any transmission.
The data in the buffer is then encrypted before the transmission can begin. On the receive side the decryption is initiated
only once the complete packet has been received in the buffer.
The encryption/decryption process takes approximately 7.0 us per 16-byte block. Thus for a maximum of 4 blocks (i.e. 64
bytes) it can take up to 28 us for completing the cryptographic operations.
The receive side sees the AES decryption time as a sequential delay before the PayloadReady interrupt is available.
The Tx side sees the AES encryption time as a sequential delay in the startup of the Tx chain, thus the startup time of the
Tx will increase according to the length of data.
In Fixed length mode the Message part of the payload that can be encrypted/decrypted can be 64 bytes long. If the
address filtering is enabled, the length of the payload should be at max 65 bytes in this case.
In Variable length mode the Max message size that can be encrypted/decrypted is also 64 bytes when address filtering is
disabled, else it is 48 bytes. Thus, including length byte, the length of the payload is max 65 or 50 bytes (the latter when
address filtering is enabled).
If the address filtering is expected then AddressFiltering must be enabled on the transmitter side as well to prevent address
byte to be encrypted.
Crc check being performed on encrypted data, CrcOk interrupt will occur "decryption time" before PayloadReady interrupt.
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5.5.6. Handling Large Packets
When Payload length exceeds FIFO size (66 bytes) whether in fixed, variable or unlimited length packet format, in addition
to PacketSent in Tx and PayloadReady or CrcOk in Rx, the FIFO interrupts/flags can be used as described below:
For Tx:
FIFO can be prefilled in Sleep/Standby but must be refilled "on-the-fly" during Tx with the rest of the payload.
1) Prefill FIFO (in Sleep/Standby first or directly in Tx mode) until FifoThreshold or FifoFull is set
2) In Tx, wait for FifoThreshold or FifoNotEmpty to be cleared (i.e. FIFO is nearly empty)
3) Write bytes into the FIFO until FifoThreshold or FifoFull is set.
4) Continue to step 2 until the entire message has been written to the FIFO (PacketSent will fire when the last bit of the
packet has been sent).
For Rx:
FIFO must be unfilled "on-the-fly" during Rx to prevent FIFO overrun.
1) Start reading bytes from the FIFO when FifoNotEmpty or FifoThreshold becomes set.
2) Suspend reading from the FIFO if FifoNotEmpty clears before all bytes of the message have been read
3) Continue to step 1 until PayloadReady or CrcOk fires
4) Read all remaining bytes from the FIFO either in Rx or Sleep/Standby mode
Note AES encryption is not feasible on large p acket s, since all Payload bytes need to be in the FIFO at the same time to
perform encryption
5.5.7. Packet Filtering
SX1231H's packet handler offers several mechanisms for packet filtering, ensuring that only useful packets are made
available to the uC, reducing significantly system power consumption and software complexity.
5.5.7.1. Sync Word Based
Sync word filtering/recognition is used for identifying the start of the payload and also for network identification. As
previously described, the Sync word recognition block is configured (size, error tolerance, value) in RegSyncValue
registers. This information is used, both for appending Sync word in Tx, and filtering packets in Rx.
Every received packet which does not start with this locally configured Sync word is automatically discarded and no
interrupt is generated.
When the Sync word is detected, payload reception automatically starts and SyncAddressMatch is asserted.
Note Sync Word values containing 0x00 byte(s) are forbidden
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5.5.7.2. Address Based
Address filtering can be enabled via the AddressFiltering bits. It adds another level of filtering, above Sync word (i.e. Sync
must match first), typically useful in a multi-node networks where a network ID is shared between all nodes (Sync word)
and each node has its own ID (address).
Two address based filtering options are available:
AddressFiltering = 01: Received address field is compared with internal register NodeAddress. If they match then the
packet is accepted and processed, otherwise it is discarded.
AddressFiltering = 10: Received address field is compared with internal registers NodeAddress and BroadcastAddress.
If either is a match, the received packet is accepted and processed, otherwise it is discarded. This additional check with
a constant is useful for implementing broadcast in a multi-node networks
Please note that the received address byte, as part of the payload, is not stripped off the packet and is made available in
the FIFO. In addition, NodeAddress and AddressFiltering only apply to Rx. On Tx side, if address filtering is expected, the
address byte should simply be put into the FIFO like any other byte of the payload.
As address filtering requires a Sync word match, both features share the same interrupt flag SyncAddressMatch.
5.5.7.3. Length Based
In variable length Packet mode, PayloadLength must be programmed with the maximum payload length permitted. If
received length byte is smaller than this maximum then the packet is accepted and processed, otherwise it is discarded.
Please note that the received length byte, as part of the payload, is not stripped off the packet and is made available in the
FIFO.
To disable this function the user should set the value of the PayloadLength to 255.
5.5.7.4. CRC Based
The CRC check is enabled by setting bit CrcOn in RegPacketConfig1. It is used for checking the integrity of the message.
On Tx side a two byte CRC checksum is calculated on the payload part of the packet and appended to the end of the
message
On Rx side the checksum is calculated on the received payload and compared with the two checksum bytes received.
The result of the comparison is stored in bit CrcOk.
By default, if the CRC check fails then the FIFO is automatically cleared and no interrupt is generated. This filtering function
can be disabled via CrcAutoClearOff bit and in this case, even if CRC fails, the FIFO is not cleared and only PayloadReady
interrupt goes high. Please note that in both cases, the two CRC checksum bytes are stripped off by the packet handler
and only the payload is made available in the FIFO.
The CRC is based on the CCITT polynomial as shown below. This implementation also detects errors due to leading and
trailing zeros.
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Figure 36. CRC Implementation
5.5.8. DC-Free Data Mechanisms
The payload to be transmitted may contain long sequences of 1's and 0's, which introduces a DC bias in the transmitted
signal. The radio signal thus produced has a non uniform power distribution over the occupied channel bandwidth. It also
introduces data dependencies in the normal operation of the demodulator. Thus it is useful if the transmitted data is random
and DC free.
For such purposes, two techniques are made available in the packet handler: Manchester encoding and data whitening.
Note Only one of the two methods should be enabled at a time.
5.5.8.1. Manchester Encoding
Manchester encoding/decoding is enabled if DcFree = 01 and can only be used in Packet mode.
The NRZ data is converted to Manchester code by coding '1' as "10" and '0' as "01".
In this case, the maximum chip rate is the maximum bit rate given in the specifications section and the actual bit rate is half
the chip rate.
Manchester encoding and decoding is only applied to the payload and CRC checksum while preamble and Sync word are
kept NRZ. However, the chip rate from preamble to CRC is the same and defined by BitRate in RegBitRate (Chip Rate =
Bit Rate NRZ = 2 x Bit Rate Manchester).
Manchester encoding/decoding is thus made transparent for the user, who still provides/retrieves NRZ data to/from the
FIFO.
Figure 37. Manchester Encoding/Decoding
X14 X13 X12 X11 X5 X0
X15
CRC Polynomial =X16 + X12 + X5 + 1
* * * X4* * *
data input
...Sync Payload...
RF chips @ BR ... 1 1 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 ...
User/NRZ bits
Manchester OFF ... 1 1 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 ...
User/NRZ bits
Manchester ON ... 1 1 1 0 1 0 0 1 0 0 1 1 ...
t
1/BR
1/BR
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5.5.8.2. Data Whitening
Another technique called whitening or scrambling is widely used for randomizing the user data before radio transmission.
The data is whitened using a random sequence on the Tx side and de-whitened on the Rx side using the same sequence.
Comparing to Manchester technique it has the advantage of keeping NRZ data rate i.e. actual bit rate is not halved.
The whitening/de-whitening process is enabled if DcFree = 10. A 9-bit LFSR is used to generate a random sequence. The
payload and 2-byte CRC checksum is then XORed with this random sequence as shown below. The data is de-whitened
on the receiver side by XORing with the same random sequence.
Payload whitening/de-whitening is thus made transparent for the user, who still provides/retrieves NRZ data to/from the
FIFO.
Figure 38. Data Whitening
X7 X6 X5 X4 X3 X2 X1 X0
X8
LFSR Polynom ia l =X9 + X5 + 1
Transmit data Whitened data
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6. Configuration and Status Registers
6.1. General Description
Table 23 Registers Summary
Address Register Name Reset
(built-in)
Default
(recom
mended) Description
0x00 RegFifo 0x00 FIFO read/write access
0x01 RegOpMode 0x04 Operating modes of the transceiver
0x02 RegDataModul 0x00 Data operation mode and Modulation settings
0x03 RegBitrateMsb 0x1A Bit Rate setting, Most Significant Bits
0x04 RegBitrateLsb 0x0B Bit Rate setting, Least Significant Bits
0x05 RegFdevMsb 0x00 Frequency Deviation setting, Most Significant Bits
0x06 RegFdevLsb 0x52 Frequency Deviation setting, Least Significant Bits
0x07 RegFrfMsb 0xE4 RF Carrier Frequency, Most Significant Bits
0x08 RegFrfMid 0xC0 RF Carrier Frequency, Intermediate Bits
0x09 RegFrfLsb 0x00 RF Carrier Frequency, Least Significant Bits
0x0A RegOsc1 0x41 RC Oscillators Settings
0x0B RegAfcCtrl 0x00 AFC control in low modulation index situations
0x0C Reserved0C 0x02 -
0x0D RegListen1 0x92 Listen Mode settings
0x0E RegListen2 0xF5 Listen Mode Idle duration
0x0F RegListen3 0x20 Listen Mode Rx duration
0x10 RegVersion 0x24 Semtech ID relating the silicon revision
0x11 RegPaLevel 0x9F PA selection and Output Power control
0x12 RegPaRamp 0x09 Control of the PA ramp time in FSK mode
0x13 RegOcp 0x1A Over Current Protection control
0x14 Reserved14 0x40 -
0x15 Reserved15 0xB0 -
0x16 Reserved16 0x7B -
0x17 Reserved17 0x9B -
0x18 RegLna 0x08 0x88 LNA settings
0x19 RegRxBw 0x86 0x55 Channel Filter BW Control
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0x1A RegAfcBw 0x8A 0x8B Channel Filter BW control during the AFC routine
0x1B RegOokPeak 0x40 OOK demodulator selection and control in peak mode
0x1C RegOokAvg 0x80 Average threshold control of the OOK demodulator
0x1D RegOokFix 0x06 Fixed threshold control of the OOK demodulator
0x1E RegAfcFei 0x10 AFC and FEI control and status
0x1F RegAfcMsb 0x00 MSB of the frequency correction of the AFC
0x20 RegAfcLsb 0x00 LSB of the frequency correction of the AFC
0x21 RegFeiMsb 0x00 MSB of the calculated frequency error
0x22 RegFeiLsb 0x00 LSB of the calculated frequency error
0x23 RegRssiConfig 0x02 RSSI-related settings
0x24 RegRssiValue 0xFF RSSI value in dBm
0x25 RegDioMapping1 0x00 Mapping of pins DIO0 to DIO3
0x26 RegDioMapping2 0x05 0x07 Mapping of pins DIO4 and DIO5, ClkOut frequency
0x27 RegIrqFlags1 0x80 Status register: PLL Lock state, Timeout, RSSI > Threshold...
0x28 RegIrqFlags2 0x00 Status register: FIFO handling flags...
0x29 RegRssiThresh 0xFF 0xE4 RSSI Threshold control
0x2A RegRxTimeout1 0x00 Timeout duration between Rx request and RSSI detection
0x2B RegRxTimeout2 0x00 Timeout duration between RSSI detection and PayloadReady
0x2C RegPreambleMsb 0x00 Preamble length, MSB
0x2D RegPreambleLsb 0x03 Preamble length, LSB
0x2E RegSyncConfig 0x98 Sync Word Recognition control
0x2F-0x36 RegSyncValue1-8 0x00 0x01 Sync Word bytes, 1 through 8
0x37 RegPacketConfig1 0x10 Packet mode settings
0x38 RegPayloadLength 0x40 Payload length setting
0x39 RegNodeAdrs 0x00 Node address
0x3A RegBroadcastAdrs 0x00 Broadcast address
0x3B RegAutoModes 0x00 Auto modes settings
0x3C RegFifoThresh 0x0F 0x8F Fifo threshold, Tx start condition
0x3D RegPacketConfig2 0x02 Packet mode settings
Address Register Name Reset
(built-in)
Default
(recom
mended) Description
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Note - Reset values are automatically refreshed in the chip at Power On Reset
- Default values are the Semtech reco mmended register values, optimizing the device operation
- Registers for which the Default value differs from the Reset value are denoted by a * in the tables of section 6
0x3E-0x4D RegAesKey1-16 0x00 16 bytes of the cypher key
0x4E RegTemp1 0x01 Temperature Sensor control
0x4F RegTemp2 0x00 Temperature readout
0x58 RegTestLna 0x1B Sensitivity boost
0x5A RegTestPa1 0x55 High Power PA settings
0x5C RegTestPa2 0x70 High Power PA settings
0x6F RegTestDagc 0x00 0x30 Fading Margin Improvement
0x71 RegTestAfc 0x00 AFC offset for low modulation index AFC
0x50 + RegTest - Internal test registers
Address Register Name Reset
(built-in)
Default
(recom
mended) Description
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6.2. Common Configuration Registers
Table 24 Common Configuration Registers
Name
(Address) Bits Variable Name Mode Default
Value Description
RegFifo
(0x00)
7-0 Fifo rw 0x00 FIFO data input/output
RegOpMode
(0x01)
7 SequencerOff rw 0 Controls the automatic Sequencer (see section 4.2 ):
0 Æ Operating mode as selected with Mode bits in
RegOpMode is automatically reached with the Sequencer
1 Æ Mode is forced by the user
6 ListenOn rw 0 Enables Listen mode, should be enabled whilst in
Standby mode:
0 Æ Off (see section 4.3)
1 Æ On
5 ListenAbort w 0 Aborts Listen mode when set together with ListenOn=0
See section 4.3.4 for details
Always reads 0.
4-2 Mode rw 001 Transceiver’s operating modes:
000 Æ Sleep mode (SLEEP)
001 Æ Standby mode (STDBY)
010 Æ Frequency Synthesizer mode (FS)
011 Æ Transmitter mode (TX)
100 Æ Receiver mode (RX)
others Æ reserved
Reads the value corresponding to the current chip mode
1-0 - r 00 unused
RegDataModul
(0x02)
7 - r 0 unused
6-5 DataMode rw 00 Data processing mode:
00 Æ Packet mode
01 Æ reserved
10 Æ Continuous mode with bit synchronizer
11 Æ Continuous mode without bit synchronizer
4-3 ModulationType rw 00 Modulation scheme:
00 Æ FSK
01 Æ OOK
10 - 11 Æ reserved
2 - r 0 unused
1-0 ModulationShaping rw 00 Data shaping:
in FSK:
00 Æ no shaping
01 Æ Gaussian filter, BT = 1.0
10 Æ Gaussian filter, BT = 0.5
11 Æ Gaussian filter, BT = 0.3
in OOK:
00 Æ no shaping
01 Æ filtering with fcutoff = BR
10 Æ filtering with fcutoff = 2*BR
11 Æ reserved
RegBitrateMsb
(0x03)
7-0 BitRate(15:8) rw 0x1a MSB of Bit Rate (Chip Rate when Manchester encoding is
enabled)
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RegBitrateLsb
(0x04)
7-0 BitRate(7:0) rw 0x0b LSB of Bit Rate (Chip Rate if Manchester encoding is
enabled)
Default value: 4.8 kb/s
RegFdevMsb
(0x05)
7-6 - r 00 unused
5-0 Fdev(13:8) rw 000000 MSB of the frequency deviation
RegFdevLsb
(0x06)
7-0 Fdev(7:0) rw 0x52 LSB of the frequency deviation
Default value: 5 kHz
RegFrfMsb
(0x07)
7-0 Frf(23:16) rw 0xe4 MSB of the RF carrier frequency
RegFrfMid
(0x08)
7-0 Frf(15:8) rw 0xc0 Middle byte of the RF carrier frequency
RegFrfLsb
(0x09)
7-0 Frf(7:0) rw 0x00 LSB of the RF carrier frequency
Default value: Frf = 915 MHz (32 MHz XO)
RegOsc1
(0x0A)
7 RcCalStart w 0 Triggers the calibration of the RC oscillator when set.
Always reads 0. RC calibration must be triggered in
Standby mode.
6 RcCalDone r 1 0 Æ RC calibration in progress
1 Æ RC calibration is over
5-0 - r 000001 unused
RegAfcCtrl
(0x0B)
7-6 - r 00 unused
5 AfcLowBetaOn rw 0 Improved AFC routine for signals with modulation index
lower than 2. Refer to section 3.4.16 for details
0 Æ Standard AFC routine
1 Æ Improved AFC routine
4-0 - r 00000 unused
Reserved0C
(0x0C)
7-0 - r 0x02 unused
BitRate FXOSC
BitRate 15 0(,)
-----------------------------------
=
Fdev Fstep Fdev 15 0(,)×=
Frf Fstep Frf 23 0;()×=
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RegListen1
(0x0D)
7-6 ListenResolIdle rw 10 Resolution of Listen mode Idle time (calibrated RC osc):
00 Æ reserved
01 Æ 64 us
10 Æ 4.1 ms
11 Æ 262 ms
5-4 ListenResolRx rw 01 Resolution of Listen mode Rx time (calibrated RC osc):
00 Æ reserved
01 Æ 64 us
10 Æ 4.1 ms
11 Æ 262 ms
3 ListenCriteria rw 0 Criteria for packet acceptance in Listen mode:
0 Æ signal strength is above RssiThreshold
1 Æ signal strength is above RssiThreshold and
SyncAddress matched
2-1 ListenEnd rw 01 Action taken after acceptance of a packet in Listen mode:
00 Æ chip stays in Rx mode. Listen mode stops and must
be disabled (see section 4.3).
01 Æ chip stays in Rx mode until PayloadReady or
Timeout interrupt occurs. It then goes to the mode defined
by Mode. Listen mode stops and must be disabled (see
section 4.3).
10 Æ chip stays in Rx mode until PayloadReady or
Timeout interrupt occurs. Listen mode then resumes in
Idle state. FIFO content is lost at next Rx wakeup.
11 Æ Reserved
0 - r 0 unused
RegListen2
(0x0E)
7-0 ListenCoefIdle rw 0xf5 Duration of the Idle phase in Listen mode.
RegListen3
(0x0F)
7-0 ListenCoefRx rw 0x20 Duration of the Rx phase in Listen mode (startup time
included, see section 4.2.3)
RegVersion
(0x10)
7-0 Version r 0x24 Version code of the chip. Bits 7-4 give the full revision
number; bits 3-0 give the metal mask revision number.
solIdleListenIdleListenCoeftListenIdle Re=
solRxListenRxListenCoeftListenRx Re=
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6.3. Transmitter Registers
Tab le 25 Transmitter Registers
Note *Power Amplifier truth table is available in Table 10
** Only the16 upper values of OutputPower are accessible
Name
(Address) Bits Variable Name Mode Default
Value Description
RegPaLevel
(0x11)
7 Pa0On * rw 1 Enables PA0, connected to RFIO and LNA
6 Pa1On * rw 0 Enables PA1, on PA_BOOST pin
5 Pa2On * rw 0 Enables PA2, on PA_BOOST pin
4-0 OutputPower rw 11111 Output power setting, with 1 dB steps
Pout = -18 + OutputPower [dBm] , with PA0
Pout = -18 + OutputPower [dBm] , with PA1**
Pout = -14+ OutputPower [dBm] , with PA1 and PA2**
Pout = -11 + OutputPower [dBm] , with PA1 and PA2, and
high Power PA settings (refer to section 3.3.7)**
RegPaRamp
(0x12)
7-4 - r 0000 unused
3-0 PaRamp rw 1001 Rise/Fall time of ramp up/down in FSK
0000 Æ 3.4 ms
0001 Æ 2 ms
0010 Æ 1 ms
0011 Æ 500 us
0100 Æ 250 us
0101 Æ 125 us
0110 Æ 100 us
0111 Æ 62 us
1000 Æ 50 us
1001 Æ 40 us
1010 Æ 31 us
1011 Æ 25 us
1100 Æ 20 us
1101 Æ 15 us
1110 Æ 12 us
1111 Æ 10 us
RegOcp
(0x13)
7-5 - r 000 unused
4 OcpOn rw 1 Enables overload current protection (OCP) for the PA:
0 Æ OCP disabled
1 Æ OCP enabled
3-0 OcpTrim rw 1010 Trimming of OCP current:
95 mA OCP by default
Imax 45 5 OcpTrim×mA()+=
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6.4. Receiver Registers
Table 26 Receiver Registers
Name
(Address) Bits Variable Name Mode Default
Value Description
Reserved14
(0x14)
7-0 - r 0x40 unused
Reserved15
(0x15)
7-0 - r 0xB0 unused
Reserved16
(0x16)
7-0 - r 0x7B unused
Reserved17
(0x17)
7-0 - r 0x9B unused
RegLna
(0x18)
7 LnaZin rw 1
*
LNA’s input impedance
0 Æ 50 ohms
1 Æ 200 ohms
6 - r 0 unused
5-3 LnaCurrentGain r 001 Current LNA gain, set either manually, or by the AGC
2-0 LnaGainSelect rw 000 LNA gain setting:
000 Æ gain set by the internal AGC loop
001 Æ G1 = highest gain
010 Æ G2 = highest gain – 6 dB
011 Æ G3 = highest gain – 12 dB
100 Æ G4 = highest gain – 24 dB
101 Æ G5 = highest gain – 36 dB
110 Æ G6 = highest gain – 48 dB
111 Æ reserved
RegRxBw
(0x19)
7-5 DccFreq rw 010
*
Cut-off frequency of the DC offset canceller (DCC):
~4% of the RxBw by default
4-3 RxBwMant rw 10
*
Channel filter bandwidth control:
00 Æ RxBwMant = 16 10 Æ RxBwMant = 24
01 Æ RxBwMant = 20 11 Æ reserved
2-0 RxBwExp rw 101
*
Channel filter bandwidth control:
FSK Mode:
OOK Mode:
See Table 14 for tabulated values
RegAfcBw
(0x1A)
7-5 DccFreqAfc rw 100 DccFreq parameter used during the AFC
4-3 RxBwMantAfc rw 01 RxBwMant parameter used during the AFC
2-0 RxBwExpAfc rw 011 * RxBwExp parameter used during the AFC
fc 4RxBw×
2π2DccFreq 2+
×
------------------------------------------
=
RxBw FXOSC
RxBwMant 2RxBwExp 2+
×
------------------------------------------------------------------
=
RxBw FXOSC
RxBwMant 2RxBwExp 3+
×
------------------------------------------------------------------
=
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RegOokPeak
(0x1B)
7-6 OokThreshType rw 01 Selects type of threshold in the OOK data slicer:
00 Æ fixed 10 Æ average
01 Æ peak 11 Æ reserved
5-3 OokPeakTheshStep rw 000 Size of each decrement of the RSSI threshold in the OOK
demodulator:
000 Æ 0.5 dB 001 Æ 1.0 dB
010 Æ 1.5 dB 011 Æ 2.0 dB
100 Æ 3.0 dB 101 Æ 4.0 dB
110 Æ 5.0 dB 111 Æ 6.0 dB
2-0 OokPeakThreshDec rw 000 Period of decrement of the RSSI threshold in the OOK
demodulator:
000 Æ once per chip 001 Æ once every 2 chips
010 Æ once every 4 chips 011 Æ once every 8 chips
100 Æ twice in each chip 101 Æ 4 times in each chip
110 Æ 8 times in each chip 111 Æ 16 times in each chip
RegOokAvg
(0x1C)
7-6 OokAverageThreshFilt rw 10 Filter coefficients in average mode of the OOK
demodulator:
00 Æ fC chip rate / 32.π 01 Æ fC chip rate / 8.π
10 Æ fC chip rate / 4.π 11 ÆfC chip rate / 2.π
5-0 - r 000000 unused
RegOokFix
(0x1D)
7-0 OokFixedThresh rw 0110
(6dB)
Fixed threshold value (in dB) in the OOK demodulator.
Used when OokThresType = 00
RegAfcFei
(0x1E)
7 - r 0 unused
6 FeiDone r 0 0 Æ FEI is on-going
1 Æ FEI finished
5 FeiStart w 0 Triggers a FEI measurement when set. Always reads 0.
4 AfcDone r 1 0 Æ AFC is on-going
1 Æ AFC has finished
3 AfcAutoclearOn rw 0 Only valid if AfcAutoOn is set
0 Æ AFC register is not cleared before a new AFC phase
1 Æ AFC register is cleared before a new AFC phase
2 AfcAutoOn rw 0 0 Æ AFC is performed each time AfcStart is set
1 Æ AFC is performed each time Rx mode is entered
1 AfcClear w 0 Clears the AfcValue if set in Rx mode. Always reads 0
0 AfcStart w 0 Triggers an AFC when set. Always reads 0.
RegAfcMsb
(0x1F)
7-0 AfcValue(15:8) r 0x00 MSB of the AfcValue, 2’s complement format
RegAfcLsb
(0x20)
7-0 AfcValue(7:0) r 0x00 LSB of the AfcValue, 2’s complement format
Frequency corre ction = AfcValue x Fstep
RegFeiMsb
(0x21)
7-0 FeiValue(15:8) r - MSB of the measured frequency offset, 2’s complement
RegFeiLsb
(0x22)
7-0 FeiValue(7:0) r - LSB of the measured frequency offset, 2’s complement
Frequency error = FeiValue x Fstep
RegRssiConfig
(0x23)
7-2 - r 000000 unused
1 RssiDone r 1 0 Æ RSSI is on-going
1 Æ RSSI sampling is finished, result available
0 RssiStart w 0 Trigger a RSSI measurement when set. Always reads 0.
RegRssiValue
(0x24)
7-0 RssiValue r 0xFF Absolute value of the RSSI in dBm, 0.5dB steps.
RSSI = -RssiValue/2 [dBm]
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6.5. IRQ and Pin Mapping Registers
Table 27 IRQ and Pin Mapping Registers
Name
(Address) Bits Variable Name Mode Default
Value Description
RegDioMapping1
(0x25)
7-6 Dio0Mapping rw 00
Mapping of pins DIO0 to DIO5
See Table 21 for mapping in Continuous mode
See Table 22 for mapping in Packet mode
5-4 Dio1Mapping rw 00
3-2 Dio2Mapping rw 00
1-0 Dio3Mapping rw 00
RegDioMapping2
(0x26)
7-6 Dio4Mapping rw 00
5-4 Dio5Mapping rw 00
3 - r 0 unused
2-0 ClkOut rw 111
*
Selects CLKOUT frequency:
000 Æ FXOSC
001 Æ FXOSC / 2
010 Æ FXOSC / 4
011 Æ FXOSC / 8
100 Æ FXOSC / 16
101 Æ FXOSC / 32
110 Æ RC (automatically enabled)
111 Æ OFF
RegIrqFlags1
(0x27)
7 ModeReady r 1 Set when the operation mode requested in Mode, is ready
- Sleep: Entering Sleep mode
- Standby: XO is running
- FS: PLL is locked
- Rx: RSSI sampling starts
- Tx: PA ramp-up completed
Cleared when changing operating mode.
6 RxReady r 0 Set in Rx mode, after RSSI, AGC and AFC.
Cleared when leaving Rx.
5 TxReady r 0 Set in Tx mode, after PA ramp-up.
Cleared when leaving Tx.
4 PllLock r 0 Set (in FS, Rx or Tx) when the PLL is locked.
Cleared when it is not.
3 Rssi rwc 0 Set in Rx when the RssiValue exceeds RssiThreshold.
Cleared when leaving Rx.
2 Timeout r 0 Set when a timeout occurs (see TimeoutRxStart and
TimeoutRssiThresh)
Cleared when leaving Rx or FIFO is emptied.
1 AutoMode r 0 Set when entering Intermediate mode.
Cleared when exiting Intermediate mode.
Please note that in Sleep mode a small delay can be
observed between AutoMode interrupt and the
corresponding enter/exit condition.
0 SyncAddressMatch r/rwc 0 Set when Sync and Address (if enabled) are detected.
Cleared when leaving Rx or FIFO is emptied.
This bit is read only in Packet mode, rwc in Continuous
mode
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RegIrqFlags2
(0x28)
7 FifoFull r 0 Set when FIFO is full (i.e. contains 66 bytes), else
cleared.
6 FifoNotEmpty r 0 Set when FIFO contains at least one byte, else cleared
5 FifoLevel r 0 Set when the number of bytes in the FIFO strictly exceeds
FifoThreshold, else cleared.
4 FifoOverrun rwc 0 Set when FIFO overrun occurs. (except in Sleep mode)
Flag(s) and FIFO are cleared when this bit is set. The
FIFO then becomes immediately available for the next
transmission / reception.
3 PacketSent r 0 Set in Tx when the complete packet has been sent.
Cleared when exiting Tx.
2 PayloadReady r 0 Set in Rx when the payload is ready (i.e. last byte
received and CRC, if enabled and CrcAutoClearOff is
cleared, is Ok). Cleared when FIFO is empty.
1 CrcOk r 0 Set in Rx when the CRC of the payload is Ok. Cleared
when FIFO is empty.
0 - r 0 unused
RegRssiThresh
(0x29)
7-0 RssiThreshold rw 0xE4
*
RSSI trigger level for Rssi interrupt :
- RssiThreshold / 2 [dBm]
RegRxTimeout1
(0x2A)
7-0 TimeoutRxStart rw 0x00 Timeout interrupt is generated TimeoutRxStart*16*Tbit
after switching to Rx mode if Rssi interrupt doesn’t occur
(i.e. RssiV alue > RssiThreshold)
0x00: TimeoutRxStart is disabled
RegRxTimeout2
(0x2B)
7-0 TimeoutRssiThresh rw 0x00 Timeout interrupt is generated TimeoutRssiThresh*16*Tbit
after Rssi interrupt if PayloadReady interrupt doesn’t
occur.
0x00: TimeoutRssiThresh is disabled
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6.6. Packet Engine Registers
Table 28 Packet Engine Registers
Name
(Address) Bits Variable Name Mode Default
Value Description
RegPreambleMsb
(0x2c)
7-0 PreambleSize(15:8) rw 0x00 Size of the preamble to be sent (from TxStartCondition
fulfilled). (MSB byte)
RegPreambleLsb
(0x2d)
7-0 PreambleSize(7:0) rw 0x03 Size of the preamble to be sent (from TxStartCondition
fulfilled). (LSB byte)
RegSyncConfig
(0x2e)
7 SyncOn rw 1 Enables the Sync word generation and detection:
0 Æ Off
1 Æ On
6 FifoFillCondition rw 0 FIFO filling condition:
0 Æ if SyncAddress interrupt occurs
1 Æ as long as FifoFillCondition is set
5-3 SyncSize rw 011 Size of the Sync word:
(SyncSize + 1) bytes
2-0 SyncTol rw 000 Number of tolerated bit errors in Sync word
RegSyncValue1
(0x2f)
7-0 SyncValue(63:56) rw 0x01
*
1st byte of Sync word. (MSB byte)
Used if SyncOn is set.
RegSyncValue2
(0x30)
7-0 SyncValue(55:48) rw 0x01
*
2nd byte of Sync word
Used if SyncOn is set and (SyncSize +1) >= 2.
RegSyncValue3
(0x31)
7-0 SyncValue(47:40) rw 0x01
*
3rd byte of Sync word.
Used if SyncOn is set and (SyncSize +1) >= 3.
RegSyncValue4
(0x32)
7-0 SyncValue(39:32) rw 0x01
*
4th byte of Sync word.
Used if SyncOn is set and (SyncSize +1) >= 4.
RegSyncValue5
(0x33)
7-0 SyncValue(31:24) rw 0x01
*
5th byte of Sync word.
Used if SyncOn is set and (SyncSize +1) >= 5.
RegSyncValue6
(0x34)
7-0 SyncValue(23:16) rw 0x01
*
6th byte of Sync word.
Used if SyncOn is set and (SyncSize +1) >= 6.
RegSyncValue7
(0x35)
7-0 SyncValue(15:8) rw 0x01
*
7th byte of Sync word.
Used if SyncOn is set and (SyncSize +1) >= 7.
RegSyncValue8
(0x36)
7-0 SyncValue(7:0) rw 0x01
*
8th byte of Sync word.
Used if SyncOn is set and (SyncSize +1) = 8.
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RegPacketConfig1
(0x37)
7 PacketFormat rw 0 Defines the packet format used:
0 Æ Fixed length
1 Æ Variable length
6-5 DcFree rw 00 Defines DC-free encoding/decoding performed:
00 Æ None (Off)
01 Æ Manchester
10 Æ Whitening
11 Æ reserved
4 CrcOn rw 1 Enables CRC calculation/check (Tx/Rx):
0 Æ Off
1 Æ On
3 CrcAutoClearOff rw 0 Defines the behavior of the packet handler when CRC
check fails:
0 Æ Clear FIFO and restart new packet reception. No
PayloadReady interrupt issued.
1 Æ Do not clear FIFO. PayloadReady interrupt issued.
2-1 AddressFiltering rw 00 Defines address based filtering in Rx:
00 Æ None (Off)
01 Æ Address field must match NodeAddress
10 Æ Address field must match NodeAddress or
BroadcastAddress
11 Æ reserved
0 - rw 0unused
RegPayloadLength
(0x38)
7-0 PayloadLength rw 0x40 If PacketFormat = 0 (fixed), payload length.
If PacketFormat = 1 (variable), max length in Rx, not used
in Tx.
RegNodeAdrs
(0x39)
7-0 NodeAddress rw 0x00 Node address used in address filtering.
RegBroadcastAdrs
(0x3A)
7-0 BroadcastAddress rw 0x00 Broadcast address used in address filtering.
RegAutoModes
(0x3B)
7-5 EnterCondition rw 000 Interrupt condition for entering the intermediate mode:
000 Æ None (AutoModes Off)
001 Æ Rising edge of FifoNotEmpty
010 Æ Rising edge of FifoLevel
011 Æ Rising edge of CrcOk
100 Æ Rising edge of PayloadReady
101 Æ Rising edge of SyncAddress
110 Æ Rising edge of PacketSent
111 Æ Falling edge of FifoNotEmpty (i.e. FIFO empty)
4-2 ExitCondition rw 000 Interrupt condition for exiting the intermediate mode:
000 Æ None (AutoModes Off)
001 Æ Falling edge of FifoNotEmpty (i.e. FIFO empty)
010 Æ Rising edge of FifoLevel or Timeout
011 Æ Rising edge of CrcOk or Timeout
100 Æ Rising edge of PayloadReady or Timeout
101 Æ Rising edge of SyncAddress or Timeout
110 Æ Rising edge of PacketSent
111 Æ Rising edge of Timeout
1-0 IntermediateMode rw 00 Intermediate mode:
00 Æ Sleep mode (SLEEP)
01 Æ Standby mode (STDBY)
10 Æ Receiver mode (RX)
11 Æ Transmitter mode (TX)
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
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RegFifoThresh
(0x3C)
7 TxStartCondition rw 1
*
Defines the condition to start packet transmission :
0 Æ FifoLevel (i.e. the number of bytes in the FIFO
exceeds FifoThreshold)
1 Æ FifoNotEmpty (i.e. at least one byte in the FIFO)
6-0 FifoThreshold rw 0001111 Used to trigger FifoLevel interrupt.
RegPacketConfig2
(0x3D)
7-4 InterPacketRxDelay rw 0000 After PayloadReady occurred, defines the delay between
FIFO empty and the start of a new RSSI phase for next
packet. Must match the transmitter’s PA ramp-down time.
- Tdelay = 0 if InterpacketRxDelay >= 12
- Tdelay = (2InterpacketRxDelay) / BitRate otherwise
3 - rw 0unused
2 RestartRx w 0 Forces the Receiver in WAIT mode, in Continuous Rx
mode.
Always reads 0.
1 AutoRxRestartOn rw 1 Enables automatic Rx restart (RSSI phase) after
PayloadReady occurred and packet has been completely
read from FIFO:
0 Æ Off. RestartRx can be used.
1 Æ On. Rx automatically restarted after
InterPacketRxDelay.
0 AesOn rw 0 Enable the AES encryption/decryption:
0 Æ Off
1 Æ On (payload limited to 66 bytes maximum)
RegAesKey1
(0x3E)
7-0 AesKey(127:120) w 0x00 1st byte of cipher key (MSB byte)
RegAesKey2
(0x3F)
7-0 AesKey(119:112) w 0x00 2nd byte of cipher key
RegAesKey3
(0x40)
7-0 AesKey(111:104) w 0x00 3rd byte of cipher key
RegAesKey4
(0x41)
7-0 AesKey(103:96) w 0x00 4th byte of cipher key
RegAesKey5
(0x42)
7-0 AesKey(95:88) w 0x00 5th byte of cipher key
RegAesKey6
(0x43)
7-0 AesKey(87:80) w 0x00 6th byte of cipher key
RegAesKey7
(0x44)
7-0 AesKey(79:72) w 0x00 7th byte of cipher key
RegAesKey8
(0x45)
7-0 AesKey(71:64) w 0x00 8th byte of cipher key
RegAesKey9
(0x46)
7-0 AesKey(63:56) w 0x00 9th byte of cipher key
RegAesKey10
(0x47)
7-0 AesKey(55:48) w 0x00 10th byte of cipher key
RegAesKey11
(0x48)
7-0 AesKey(47:40) w 0x00 11th byte of cipher key
RegAesKey12
(0x49)
7-0 AesKey(39:32) w 0x00 12th byte of cipher key
RegAesKey13
(0x4A)
7-0 AesKey(31:24) w 0x00 13th byte of cipher key
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
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6.7. Temperature Sensor Registers
Table 29 Temperature Sensor Registers
6.8. Test Registers
Table 30 Test Registers
RegAesKey14
(0x4B)
7-0 AesKey(23:16) w 0x00 14th byte of cipher key
RegAesKey15
(0x4C)
7-0 AesKey(15:8) w 0x00 15th byte of cipher key
RegAesKey16
(0x4D)
7-0 AesKey(7:0) w 0x00 16th byte of cipher key (LSB byte)
Name
(Address) Bits Variable Name Mode Default
Value Description
RegTemp1
(0x4E)
7-4 - r 0000 unused
3 TempMeasStart w 0 Triggers the temperature measurement when set. Always
reads 0.
2 TempMeasRunning r 0 Set to 1 while the temperature measurement is running.
Toggles back to 0 when the measurement has completed.
The receiver can not be used while measuring
temperature
1-0 - r 01 unused
RegTemp2
(0x4F)
7-0 TempValue r - Measured temperature
-1°C per Lsb
Needs calibration for accuracy
Name
(Address) Bits Variable Name Mode Default
Value Description
RegTestLna
(0x58)
7-0 SensitivityBoost rw 0x1B High sensitivity or normal sensitivity mode:
0x1B Æ Normal mode
0x2D Æ High sensitivity mode
RegTestPa1
(0x5A)
7-0 Pa20dBm1 rw 0x55 Set to 0x5D for +20 dBm operation on PA_BOOST.
0x55 Æ Normal mode and Rx mode
0x5D Æ +20 dBm mode
Revert to 0x55 when receiving or using PA0
RegTestPa2
(0x5C)
7-0 Pa20dBm2 rw 0x70 Set to 0x7C for +20 dBm operation on PA_BOOST
0x70 Æ Normal mode and Rx mode
0x7C Æ +20 dBm mode
Revert to 0x70 when receiving or using PA0
RegTestDagc
(0x6F)
7-0 ContinuousDagc rw 0x30
*
Fading Margin Improvement, refer to 3.4.4
0x00 Æ Normal mode
0x20 Æ Improved margin, use if AfcLowBetaOn=1
0x30 Æ Improved margin, use if AfcLowBetaOn=0
RegTestAfc
(0x71)
7-0 LowBetaAfcOffset rw 0x00 AFC offset set for low modulation index systems, used if
AfcLowBetaOn=1.
Offset = LowBetaAfcOffset x 488 Hz
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
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7. Application Information
7.1. Crystal Resonator Specification
Table 31 shows the crystal resonator specification for the crystal reference oscillator circuit of the SX1231H. This
specification covers the full range of operation of the SX1231H and is employed in the reference design.
Table 31 Crystal Specification
Notes - the initial frequency tolerance, temperature stability and ageing performance should be chosen in accordance
with the target operating temperature range and the receiver bandwidth selected.
- the loading capacitance should be applied externally, and adapted to the actual Cload specification of the XTAL.
- A minimum XTAL frequency of 28 MHz is required to cover th e 863- 870 MHz band , 29 MHz for the 902-9 28 MHz
band
7.2. Reset of the Chip
A power-on reset of the SX1231H is triggered at power up. Additionally, a manual reset can be issued by controlling pin 6.
7.2.1. POR
If the application requires the disconnection of VDD from the SX1231H, despite of the extremely low Sleep Mode current,
the user should wait for 10 ms from of the end of the POR cycle before commencing communications over the SPI bus. Pin
6 (Reset) should be left floating during the POR sequence.
Figure 39. POR Timing Diagram
Please note that any CLKOUT activity can also be used to detect that the chip is ready.
Symbol Description Conditions Min Typ Max Unit
FXOSC XTAL Frequency 26 - 32 MHz
RS XTAL Serial Resistance - 30 140 ohms
C0 XTAL Shunt Capacitance - 2.8 7 pF
CLOAD External Foot Capacitance On each pin XTA and XTB 8 16 22 pF
Wait for
10 ms
VDD
Pin 6
(output)
Chip is ready from
this point on
Undefined
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
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7.2.2. Manual Reset
A manual reset of the SX1231H is possible even for applications in which VDD cannot be physically disconnected. Pin 6
should be pulled high for a hundred microseconds, and then released. The user should then wait for 5 ms before using the
chip.
Figure 40. Manual Reset Timing Diagram
Note whilst pin 6 is driven high, an over current consumption of up to ten milliamps can be seen on VDD.
7.3. Reference Design
Please contact your Semtech representative for evaluation tools, reference designs and design assistance. Note that all
schematics shown in this section are full schematics, listing ALL required components, including decoupling capacitors.
Figure 41. +13dBm Schematic
VDD
> 100 us
Chip is ready from
this point on
Pin 6
(
in
p
ut
)
High-Z High-Z’’1’’
Wait for
5 ms
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
Rev 1 - Oct 2011
Table 32 +13dBm BOM
Figure 42. +17/20dBm Schematic
Table 33 +17/20dBm BOM
Designator 315 MHz 433 MHz 868 MHz 915 MHz Type
C8, C9, C10, C13 100 nF X7R
C1 10 nF X7R
C11, C12 15 pF COG
L1 1.5 nH 10 nH 4.7 nH 3.9 nH
Wirewound air core
or multilayer*
L2 33 nH 33 nH 33 nH 33 nH
L3 22 nH 12 nH 6.8 nH 6.8 nH
L4 18 nH 10 nH 6.8 nH 6.8 nH
C2 15 pF 15 pF 5.6 pF 4.7 pF
COG
C3 33 pF 22 pF 47 pF 8.2 pF
C4 - 2.7 pF - -
C5 15 pF 15 pF 8.2 pF 6.8 pF
C6 - - - -
C7 12 pF 8.2 pF 6.8 pF 5.6 pF
Designator 315 MHz 433 MHz 868 MHz 915 MHz Type
C8, C9, C10, C13 100 nF X7R
C1 10 nF X7R
C11, C12 15 pF COG
L1 1.5 nH 1.5 nH 2.2 nH 2.7 nH
Wirewound air core
or multilayer (1)
L2 33 nH 22 nH 22 nH 22 nH
L3 22 nH 12 nH 5.6 nH 5.6 nH
L4 33 nH 15 nH 5.6 nH 5.6 nH
L5 39 nH 33 nH - -
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
Rev 1 - Oct 2011
Notes - Comple te details on selected components a re availa bl e in the re fe rence d esign package, downloadable from the
Semtech website
- (1) Inductor values may change when using multilayer type components
- (2) An additional DC-cut capacitor (typ. 47pF) might be required with this matching topology and certain RF
switches
- In very cost-sensitive and/or size-con strained application s where it is acceptable to degrade the receiver
sensitivity by appro xim at ely 2 dB, L5 and C14 can be omitte d
C2 22 pF 18 pF 8.2 pF 8.2 pF
COG
C3 68 pF 33 pF 22 pF 22 pF
C4 - 2.7 pF - -
C5 22 pF 15 pF 6.8 pF 6.8 pF
C6 - - - -
C7 12 pF 8.2 pF 3.3 pF 3.3 pF
C14 - - 5.6 pF 5.6 pF
C15 12 pF 12 pF 6.8 nH
(2)
5.6 nH
(2)
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
Rev 1 - Oct 2011
8. Packaging Information
8.1. Package Outline Drawing
The SX1231H is available in a 24-lead QFN package as show in Figure 43.
Figure 43. Package Outline Drawing
8.2. Recommended Land Pattern
Figure 44. Recommended Land Pattern
MILLIMETERS
0.65 BSC
0.00A1
E1
aaa
bbb
N
e
L
A2
D1
D
E
b
0.35
4.90
4.90
3.20
-
0.25
DIM
A
DIMENSIONS
0.80
MIN
-0.05
5.10
5.10
3.30
0.45
0.35
0.40
0.10
0.08
24
5.00
(0.20)
3.25
5.00
0.30
-
1.00
MAX
-
NOM
B
aaa C
3.20 3.25 3.30
D
E
A
A2
A1
e/2
e
bxN
LxN
E/2
D/2
D1
E1
C
SEATING
PLANE
1
2
N
bbb C A B
COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
NOTES:
2.
1.
A
PIN 1
INDICATOR
(LASER MARK)
K
HGZ
(C)
Y
P
X
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
NOTES:
2.
DIM
X
Y
H
K
P
C
G
MILLIMETERS
(4.90)
0.35
0.80
3.30
0.65
3.30
4.10
DIMENSIONS
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
5.70
Z
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
3.
4. SQUARE PACKAGE-DIMENSIONS APPLY IN BOTH X AND Y DIRECTIONS.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
1.
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
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8.3. Thermal Impedance
The thermal impedance of this package is: Theta ja = 23.8° C/W typ., calculated from a package in still air, on a 4-layer
FR4 PCB, as per the Jedec standard.
8.4. Tape & Reel Specification
Figure 45. Tape & Reel Specification
Note Single Sprocket holes
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SX1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
Rev 1 - Oct 2011
9. Revision History
Table 34 Revision History
Revision Date Comment
1 October 2011 First FINAL datasheet version
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Advanced Communication and Sensing Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805) 498-2111 Fax: (805) 498-3804
E-mail: sales@semtech.com
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Internet: http://www.semtech.co m
Contact information
© Semtech 2011
A
ll rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The
information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable
and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication
thereof does not convey nor imply any license under patent or other industrial or intellectual property rights. Semtech assumes
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SEMTECH PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN
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SX1231H
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