Semtech SX1211I084T Schematic [ru]

WIRELESS & SENSING

SX1211 Transceiver

Ultra-Low Power Integrated UHF Transceiver

General Description

The SX1211 is a low cost single-chip transceiver
operating in the frequency ranges from 863-870, 902­928 MHz and 950-960 MHz. The SX1211 is optimized
for very low power consumption (3mA in receiver
mode). It incorporates a baseband modem with data
rates up to 200 kb/s. Data handling features include a
sixty-four byte FIFO, packet handling, automatic CRC
generation and data whitening. Its highly integrated
architecture allows for minimum external component
count whilst maintaining design flexibility. All major RF
communication parameters are programmable and
most of them may be dynamically set. It complies with
European (ETSI EN 300-220 V2.1.1) and North
American (FCC part 15.247 and 15.249) regulatory
standards.

Ordering Information

Table 1: Ordering Information

Part number Delivery

SX1211I084TRT Tape & Reel 3000 pieces

SX1211I084T Tray 200 pieces

SX1211WS Wafer 1 wafer

 TQFN-32 package – Operating range [-40;+85°C]
 T refers to Lead Free packaging
 This device is WEEE and RoHS compliant

Minimum Order

Quantity / Multiple

Features

 Low Rx power consumption: 3mA
 Low Tx power consumption: 25 mA @ +10 dBm
 Good reception sensitivity: down to -107 dBm at

25 kb/s in FSK, -113 dBm at 2kb/s in OOK

 Programmable RF output power: up to +12.5 dBm

in 8 steps

 Packet handling feature with data whitening and

automatic CRC generation

 Wide RSSI (Received Signal Strength Indicator)

dynamic range, 70dB from Rx noise floor

 Bit rates up to 200 kb/s, NRZ coding
 On-chip frequency synthesizer
 FSK and OOK modulation
 Incoming sync word recognition
 Built-in Bit-Synchronizer for incoming data and

clock synchronization and recovery

 5 x 5 mm TQFN package
 Optimized Circuit Configuration for Low-cost

applications

Applications

 Wireless alarm and security systems
 Wireless sensor networks
 Automated Meter Reading
 Home and building automation
 Industrial monitoring and control
 Remote Wireless Control

Application Circuit Schematic

Rev 8– February 2013 Page 1 of 92 www.semtech.com

WIRELESS & SENSING

Table of Contents

SX1211

1. General Description ................................................................... 5

1.1. Simplified Block Diagram ........................................................ 5

1.2. Pin Diagram ............................................................................ 6

1.3. Pin Description ........................................................................ 7

2. Electrical Characteristics ............................................................ 8

2.1. ESD Notice.............................................................................. 8

2.2. Absolute Maximum Ratings .................................................... 8

2.3. Operating Range ..................................................................... 8

2.4. Chip Specification ................................................................... 8

2.4.1. Power Consumption ............................................................. 8

2.4.2. Frequency Synthesis ........................................................... 9

2.4.3. Transmitter ........................................................................... 9

2.4.4. Receiver ............................................................................. 10

2.4.5. Digital Specification ............................................................ 11

3. Architecture Description ........................................................... 12

3.1. Power Supply Strategy.......................................................... 12

3.2. Frequency Synthesis Description ......................................... 13

3.2.1. Reference Oscillator .......................................................... 13

3.2.2. CLKOUT Output ................................................................. 13

3.2.3. PLL Architecture ................................................................ 14

3.2.4. PLL Tradeoffs..................................................................... 14

3.2.5. Voltage Controlled Oscillator ............................................. 15

3.2.6. PLL Loop Filter ................................................................... 16

3.2.7. PLL Lock Detection Indicator ............................................. 16

3.2.8. Frequency Calculation ....................................................... 16

3.3. Transmitter Description ......................................................... 18

3.3.1. Architecture Description ..................................................... 18

3.3.2. Bit Rate Setting .................................................................. 19

3.3.3. Alternative Settings ............................................................ 19

3.3.4. Fdev Setting in FSK Mode ................................................. 19

3.3.5. Fdev Setting in OOK Mode ................................................ 19

3.3.6. Interpolation Filter .............................................................. 20

3.3.7. Power Amplifier .................................................................. 20

3.3.8. Common Input and Output Front-End ................................ 22

3.4. Receiver Description ............................................................. 23

3.4.1. Architecture ........................................................................ 23

3.4.2. LNA and First Mixer ........................................................... 24

3.4.3. IF Gain and Second I/Q Mixer ........................................... 24

3.4.4. Channel Filters ................................................................... 24

3.4.5. Channel Filters Setting in FSK Mode ................................. 25

3.4.6. Channel Filters Setting in OOK Mode ................................ 26

3.4.7. RSSI ................................................................................... 26

3.4.8. Fdev Setting in Receive Mode ........................................... 28

3.4.9. FSK Demodulator .............................................................. 28

3.4.10. OOK Demodulator ........................................................... 28

3.4.11. Bit Synchronizer ............................................................... 31

3.4.12. Alternative Settings .......................................................... 32

3.4.13. Data Output ...................................................................... 32

4. Operating Modes...................................................................... 33

4.1. Modes of Operation .............................................................. 33

4.2. Digital Pin Configuration vs. Chip Mode ............................... 33

5. Data Processing ....................................................................... 34

5.1. Overview ............................................................................... 34

5.1.1. Block Diagram .................................................................... 34

5.1.2. Data Operation Modes ....................................................... 34

5.2. Control Block Description ...................................................... 35

5.2.1. SPI Interface ...................................................................... 35

5.2.2. FIFO ................................................................................... 38

5.2.3. Sync Word Recognition ..................................................... 40

5.2.4. Packet Handler................................................................... 40

5.2.5. Control ................................................................................ 40

5.3. Continuous Mode .................................................................. 41

5.3.1. General Description ............................................................41

5.3.2. Tx Processing .....................................................................41

5.3.3. Rx Processing .....................................................................42

5.3.4. Interrupt Signals Mapping ...................................................42

5.3.5. uC Connections ..................................................................43

5.3.6. Continuous Mode Example .................................................43

5.4. Buffered Mode .......................................................................44

5.4.1. General Description ............................................................44

5.4.2. Tx Processing .....................................................................44

5.4.3. Rx Processing .....................................................................45

5.4.4. Interrupt Signals Mapping ...................................................46

5.4.5. uC Connections ..................................................................47

5.4.6. Buffered Mode Example .....................................................47

5.5. Packet Mode ..........................................................................49

5.5.1. General Description ............................................................49

5.5.2. Packet Format .....................................................................49

5.5.3. Tx Processing .....................................................................51

5.5.4. Rx Processing .....................................................................51

5.5.5. Packet Filtering ...................................................................52

5.5.6. DC-Free Data Mechanisms ................................................53

5.5.7. Interrupt Signal Mapping .....................................................54

5.5.8. uC Connections ..................................................................55

5.5.9. Packet Mode Example ........................................................56

5.5.10. Additional Information .......................................................56

6. Configuration and Status Registers ..........................................58

6.1. General Description ...............................................................58

6.2. Main Configuration Register - MCParam ...............................58

6.3. Interrupt Configuration Parameters - IRQParam ...................60

6.4. Receiver Configuration parameters - RXParam ....................62

6.5. Sync Word Parameters - SYNCParam ..................................63

6.6. Transmitter Parameters - TXParam .......................................64

6.7. Oscillator Parameters - OSCParam .......................................64

6.8. Packet Handling Parameters – PKTParam ............................65

7. Application Information .............................................................66

7.1. Crystal Resonator Specification .............................................66

7.2. Software for Frequency Calculation .......................................66

7.2.1. GUI ......................................................................................66

7.2.2. .dll for Automatic Production Bench ....................................66

7.3. Switching Times and Procedures ..........................................66

7.3.1. Optimized Receive Cycle ....................................................67

7.3.2. Optimized Transmit Cycle ...................................................68

7.3.3. Transmitter Frequency Hop Optimized Cycle .....................69

7.3.4. Receiver Frequency Hop Optimized Cycle .........................70

7.3.5. RxÆTx and TxÆRx Jump Cycles .......................................71

7.4. Reset of the Chip ...................................................................72

7.4.1. POR ....................................................................................72

7.4.2. Manual Reset ......................................................................72

7.5. Reference Design ..................................................................73

7.5.1. Application Schematic .........................................................73

7.5.2. PCB Layout .........................................................................73

7.5.3. Bill Of Material .....................................................................74

7.5.4. SAW Filter Plot ....................................................................75

7.5.5. Ordering Information for Tools ............................................75

7.6. Reference Design Performance .............................................76

7.6.1. Sensitivity Flatness .............................................................77

7.6.2. Sensitivity vs. LO Drift .........................................................78

7.6.3. Sensitivity vs. Receiver BW ................................................79

7.6.4. Sensitivity Stability over Temperature and Voltage ............80

7.6.5. Sensitivity vs. Bit Rate ........................................................80

7.6.6. Adjacent Channel Rejection ................................................81

7.6.7. Output Power Flatness .......................................................82

7.6.8. Pout and IDD vs. PA Setting ...............................................83

Rev 8 – February 2013

Page 2 of 92 www.semtech.com

WIRELESS & SENSING

7.6.9. Pout Stability over Temperature and Voltage .................... 84

7.6.10. Transmitter Spectral Purity .............................................. 85

7.6.11. OOK Channel Bandwidth ................................................. 86

7.6.12. FSK Spectrum in Europe ................................................. 87

7.6.13. Digital Modulation Schemes ............................................ 88

7.6.14. Current Stability over Temperature and Voltage .............. 89

Index of Figures

SX1211

8. Packaging Information ..............................................................90

8.1. Package Outline Drawing ......................................................90

8.2. PCB Land Pattern ..................................................................90

8.3. Tape & Reel Specification ......................................................91

9. Revision History ........................................................................92

10. Contact Information .................................................................92

Figure 1: SX1211 Simplified Block Diagram .................................. 5

Figure 2: SX1211 Pin Diagram ...................................................... 6

Figure 3: SX1211 Detailed Block Diagram .................................. 12

Figure 4: Power Supply Breakdown ............................................. 13

Figure 5: Frequency Synthesizer Description .............................. 14

Figure 6: LO Generator ................................................................ 14

Figure 7: Loop Filter ..................................................................... 16

Figure 8: Transmitter Architecture ............................................... 18

Figure 9: I(t), Q(t) Overview ......................................................... 18

Figure 10: PA Control................................................................... 21

Figure 11: Optimal Load Impedance Chart .................................. 21

Figure 12: Recommended PA Biasing and Output Matching ..... 22

Figure 13: Front-end Description ................................................. 22

Figure 14: Receiver Architecture ................................................. 23

Figure 15: FSK Receiver Setting ................................................. 23

Figure 16: OOK Receiver Setting ................................................ 23

Figure 17: Active Channel Filter Description ................................ 24

Figure 18: Butterworth Filter's Actual BW .................................... 26

Figure 19: Polyphase Filter's Actual BW ...................................... 26

Figure 20: RSSI Dynamic Range ................................................. 27

Figure 21: RSSI IRQ Timings ...................................................... 28

Figure 22: OOK Demodulator Description ................................... 29

Figure 23: Floor Threshold Optimization ...................................... 30

Figure 24: BitSync Description ..................................................... 31

Figure 25: SX1211’s Data Processing Conceptual View ............. 34

Figure 26: SPI Interface Overview and uC Connections ............. 35

Figure 27: Write Register Sequence ............................................ 36

Figure 28: Read Register Sequence ............................................ 37

Figure 29: Write Bytes Sequence (ex: 2 bytes) ........................... 37

Figure 30: Read Bytes Sequence (ex: 2 bytes) ........................... 38

Figure 31: FIFO and Shift Register (SR) ...................................... 38

Figure 32: FIFO Threshold IRQ Source Behavior ........................ 39

Figure 33: Sync Word Recognition .............................................. 40

Figure 34: Continuous Mode Conceptual View ............................ 41

Figure 35: Tx Processing in Continuous Mode ............................ 41

Figure 36: Rx Processing in Continuous Mode ............................ 42

Figure 37: uC Connections in Continuous Mode ......................... 43

Figure 38: Buffered Mode Conceptual View ................................ 44

Figure 39: Tx processing in Buffered Mode ................................. 45

Figure 40: Rx Processing in Buffered Mode ................................ 46

Figure 41: uC Connections in Buffered Mode .............................. 47

Figure 42: Packet Mode Conceptual View ................................... 49

Figure 43: Fixed Length Packet Format ....................................... 50

Figure 44: Variable Length Packet Format .................................. 51

Figure 45: CRC Implementation .................................................. 53

Figure 46: Manchester Encoding/Decoding ..................................54

Figure 47: Data Whitening ............................................................54

Figure 48: uC Connections in Packet Mode .................................55

Figure 49: Optimized Rx Cycle .....................................................67

Figure 50: Optimized Tx Cycle ......................................................68

Figure 51: Tx Hop Cycle ...............................................................69

Figure 52: Rx Hop Cycle ...............................................................70

Figure 53: Rx Æ Tx Æ Rx Cycle ...................................................71

Figure 54: POR Timing Diagram ...................................................72

Figure 55: Manual Reset Timing Diagram ....................................72

Figure 56: Reference Design Circuit Schematic ...........................73

Figure 57: Reference Design‘s Stackup .......................................74

Figure 58: Reference Design Layout (top view) ............................74

Figure 59: 915 MHz SAW Filter Plot .............................................75

Figure 60: 869 MHz SAW Filter Plot .............................................75

Figure 61: Sensitivity Across the 868 MHz Band ..........................77

Figure 62: Sensitivity Across the 915 MHz Band ..........................77

Figure 63: FSK Sensitivity Loss vs. LO Drift .................................78

Figure 64: OOK Sensitivity Loss vs. LO Drift ................................78

Figure 65: FSK Sensitivity vs. Rx BW ...........................................79

Figure 66: OOK Sensitivity Change vs. Rx BW ............................79

Figure 67: Sensitivity Stability .......................................................80

Figure 68: FSK Sensitivity vs. BR .................................................80

Figure 69: OOK Sensitivity vs. BR ................................................81

Figure 70: ACR in FSK Mode .......................................................81

Figure 71: ACR in OOK Mode ......................................................82

Figure 72: Pout for 869 MHz Band Operation ...............................82

Figure 73: Pout for 915 MHz Band Operation ...............................83

Figure 74: Pout and IDD at all PA Settings, 869 MHz ..................83

Figure 75: Pout and IDD at all PA Settings, 915 MHz ..................84

Figure 76: Pout Stability ................................................................84

Figure 77: 869 MHz Spectral Purity DC-1GHz .............................85

Figure 78: 869 MHz Spectral Purity 1-6GHz .................................85

Figure 79: OOK Spectrum - 2kbps ................................................86

Figure 80: OOK Spectrum - 8kbps ................................................86

Figure 81: OOK Spectrum - 16.7kbps ...........................................86

Figure 82: FSK - 1.56kbps - +/-33 kHz .........................................87

Figure 83: FSK - 25 kbps - +/-50 kHz ...........................................87

Figure 84: FSK - 40 kbps - +/-40 kHz ...........................................87

Figure 85: DTS 6dB Bandwidth ....................................................88

Figure 86: DTS Power Spectral Density .......................................88

Figure 87: IDD vs. Temp and VDD ...............................................89

Figure 88: Package Outline Drawing ............................................90

Figure 89: PCB Land Pattern ........................................................90

Figure 90: Tape & Reel Dimensions .............................................91

Rev 8 – February 2013

Page 3 of 92 www.semtech.com

WIRELESS & SENSING

Index of Tables

SX1211

Table 1: Ordering Information ........................................................ 1

Table 2: SX1211 Pinouts ............................................................... 7

Table 3: Absolute Maximum Ratings ............................................. 8

Table 4: Operating Range .............................................................. 8

Table 5: Power Consumption Specification ................................... 8

Table 6: Frequency Synthesizer Specification ............................... 9

Table 7: Transmitter Specification ................................................. 9

Table 8: Receiver Specification.................................................... 10

Table 9: Digital Specification ........................................................ 11

Table 10: MCParam_Freq_band Setting ..................................... 15

Table 11: PA Rise/Fall Times....................................................... 20

Table 12: Operating Modes ......................................................... 33

Table 13: Pin Configuration vs. Chip Mode ................................. 33

Table 14: Data Operation Mode Selection ................................... 35

Table 15: Config vs. Data SPI Interface Selection ....................... 36

Table 16: Status of FIFO when Switching Between Different

Modes of the Chip ........................................................................ 39

Table 17: Interrupt Mapping in Continuous Rx Mode .................. 42

Table 18: Interrupt Mapping in Continuous Tx Mode ................... 42

Table 19: Relevant Config. Registers in Continuous Mode ........ 43

Acronyms

BOM Bill Of Materials
BR Bit Rate
BW Bandwidth

CCITT

CP Charge Pump
CRC Cyclic Redundancy Check
DAC Digital to Analog Converter
DDS Direct Digital Synthesis
DLL Dynamically Linked Library

ERP

ETSI

FCC Federal Communications Commission
Fdev Frequency Deviation
FIFO First In First Out
FS Frequency Synthesizer
FSK Frequency Shift Keying
GUI Graphical User Interface
IC Integrated Circuit
ID IDentificator
IF Intermediate Frequency
IRQ Interrupt ReQuest
ITU International Telecommunication Union
LFSR Linear Feedback Shift Register
LNA Low Noise Amplifier

Comité Consultatif International
Téléphonique et Télégraphique - ITU

Equivalent Radiated Power
European Telecommunications Standards
Institute

Table 20: Interrupt Mapping in Buffered Rx and Stby Modes .......46

Table 21: Interrupt Mapping in Buffered Tx Mode ........................46

Table 22: Relevant Configuration Registers in Buffered Mode .....47

Table 23: Interrupt Mapping in Rx and Stby in Packet Mode ........55

Table 24: Interrupt Mapping in Tx Packet Mode ...........................55

Table 25: Relevant Configuration Registers in Packet Mode .......56

Table 26: Registers List ................................................................58

Table 27: MCParam Register Description ....................................58

Table 28: IRQParam Register Description ....................................60

Table 29: RXParam Register Description .....................................62

Table 30: SYNCParam Register Description ................................63

Table 31: TXParam Register Description .....................................64

Table 32: OSCParam Register Description ..................................64

Table 33: PKTParam Register Description ...................................65

Table 34: Crystal Resonator Specification ....................................66

Table 35: Reference Design BOM ................................................74

Table 36: Tools Ordering Information ...........................................75

Table 37: FSK Rx Filters vs. Bit Rate ...........................................76

Table 38: OOK Rx Filters vs. Bit Rate ..........................................76

LO Local Oscillator
LSB Least Significant Bit
MSB Most Significant Bit
NRZ Non Return to Zero
NZIF Near Zero Intermediate Frequency
OOK On Off Keying
PA Power Amplifier
PCB Printed Circuit Board
PFD Phase Frequency Detector
PLL Phase-Locked Loop
POR Power On Reset
RBW Resolution BandWidth
RF Radio Frequency
RSSI Received Signal Strength Indicator
Rx Receiver
SAW Surface Acoustic Wave
SPI Serial Peripheral Interface
SR Shift Register
Stby Standby
Tx Transmitter
uC Microcontroller
VCO Voltage Controlled Oscillator
XO Crystal Oscillator
XOR eXclusive OR

Rev 8 – February 2013

Page 4 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

This product datasheet contains a detailed description of the SX1211 performance and functionality. Please consult
the Semtech website for the latest updates or errata.

1. General Description

The SX1211 is a single chip FSK and OOK transceiver capable of operation in the 863-870 MHz and 902-928 MHz
license free ISM frequency bands, as well as the 950 - 960 MHz frequency band. It complies with both the relevant
European and North American standards, EN 300-220 V2.1.1 (June 2006 release) and FCC Part 15 (10-1-2006
edition). A unique feature of this circuit is its extremely low current consumption in receiver mode of only 3mA (typ).
The SX1211 comes in a 5x5 mm TQFN-32 package.

1.1. Simplified Block Diagram

Rev 8 – February 2013

Figure 1: SX1211 Simplified Block Diagram

Page 5 of 92 www.semtech.com

WIRELESS & SENSING

1.2. Pin Diagram

The following diagram shows the pins arrangement of the QFN package, top view.

SX1211

Notes:

 yyww refers to the date code
 ------ refers to the lot number

Figure 2: SX1211 Pin Diagram

Rev 8 – February 2013

Page 6 of 92 www.semtech.com

WIRELESS & SENSING

1.3. Pin Description

Table 2: SX1211 Pinouts

Number Name Type Description

0 GND I Exposed ground pad
1 TEST5 I/O Connect to GND
2 TEST1 I/O Connect to GND
3 VR_VCO O Regulated supply of the VCO
4 VCO_M I/O VCO tank
5 VCO_P I/O VCO tank
6 LF_M I/O PLL loop filter
7 LF_P I/O PLL loop filter
8 TEST6 I/O Connect to GND

9 TEST7 I/O Connect to GND
10 XTAL_P I/O Crystal connection
11 XTAL_M I/O Crystal connection
12 TEST0 I Connect to GND
13 TEST8 I/O POR. Do not connect if unused
14 NSS_CONFIG I SPI CONFIG enable
15 NSS_DATA I SPI DATA enable
16 MISO O SPI data output
17 MOSI I SPI data input
18 SCK I SPI clock input
19 CLKOUT O Clock output
20 DATA I/O NRZ data input and output (Continuous mode)
21 IRQ_0 O Interrupt output
22 IRQ_1 O Interrupt output
23 PLL_LOCK O PLL lock detection output
24 TEST2 I/O Connect to GND
25 TEST3 I/O Connect to GND
26 VDD I Supply voltage
27 VR_1V O Regulated supply of the analog circuitry
28 VR_DIG O Regulated supply of digital circuitry

29 VR_PA O Regulated supply of the PA
30 TEST4 I/O Connect to GND
31 RFIO I/O RF input/output
32 NC - Connect to GND

Note: pin 13 (Test 8) can be used as an manual reset trigger. See section 7.4.2 for details on its use.

SX1211

Rev 8 – February 2013

Page 7 of 92 www.semtech.com

WIRELESS & SENSING

2. Electrical Characteristics

SX1211

2.1. ESD Notice

The SX1211 is a high performance radio frequency device. It satisfies:
 Class 2 of the JEDEC standard JESD22-A114-B (Human Body Model), except on pins 3-4-5-27-28-29-31

where it satisfies Class 1A.
 Class III of the JEDEC standard JESD22-C101C (Charged Device Model) on all 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 3: Absolute Maximum Ratings

Symbol Description Min Max Unit

VDDmr Supply voltage -0.3 3.7 V

Tmr Storage temperature -55 125 °C
Pmr Input level - 0 dBm

2.3. Operating Range

Table 4: Operating Range

Symbol Description Min Max Unit

VDDop Supply Voltage 2.1 3.6 V

Trop Temperature -40 +85 °C

ML Input Level - 0 dBm

2.4. Chip Specification

Conditions: Temp = 25 °C, VDD = 3.3 V, crystal frequency = 12.8 MHz, carrier frequency = 869 or 915 MHz,
modulation FSK, data rate = 25 kb/s, Fdev = 50 kHz, fc = 100 kHz, unless otherwise specified.

Note: RF performance depends on assembly. Electrical specifications listed in this section are obtained with the
TQFN package described in section 8 “Packaging Information”.

2.4.1. Power Consumption

Table 5: Power Consumption Specification

Symbol Description Conditions Min Typ Max Unit

IDDSL Supply current, Sleep mode

IDDST

IDDFS Supply current in FS mode

IDDR Supply current in Rx mode - 3.0 3.5 mA

IDDT Supply current in Tx mode

Rev 8 – February 2013

Supply current in standby
mode, CLKOUT disabled

Crystal oscillator running

Frequency synthesizer
running

Output power = +10 dBm
Output power = 1dBm

(1)

Page 8 of 92 www.semtech.com

(2)

- 65 80 µA

- 0.1 2 µA

- 1.3 1.7 mA

-

-

25
16

30
21

mA
mA

SX1211

(1)

(1)

WIRELESS & SENSING

(1)

Guaranteed by design and characterization

(2)

Crystal Cload=10pF, C0=2.5pF, Rm=15 Ohms

2.4.2. Frequency Synthesis

Table 6: Frequency Synthesizer Specification

Symbol Description Conditions Min Typ Max Unit

FR Frequency ranges

BR_F Bit rate (FSK) NRZ 1.56 - 200 Kb/s
BR_O Bit rate (OOK) NRZ 1.56 - 32 Kb/s
FDA Frequency deviation (FSK) 33 50 200 kHz
XTAL Crystal oscillator frequency 9 12.8 15 MHz

FSTEP

TS_OSC Oscillator wake-up time From Sleep mode

TS_FS

TS_HOP

(1)

Guaranteed by design and characterization

Frequency synthesizer
step

Frequency synthesizer
wake-up time at most
10 kHz away from the
target

Frequency synthesizer hop
time at most 10 kHz away
from the target

Programmable but requires
specific BOM

Variable, depending on the
frequency.

- 1.5 5 ms

From Stby mode - 500 800 µs

200 kHz step - 180 - µs
1 MHz step - 200 - µs

5 MHz step - 250 - µs

7 MHz step - 260 - µs

12 MHz step - 290 - µs

20 MHz step - 320 - µs
27 MHz step - 340 - µs

863
902
950

- 2 - kHz

-

-

-

870
928
960

MHz
MHz
MHz

2.4.3. Transmitter

Table 7: Transmitter Specification

Symbol Description Conditions Min Typ Max Unit

RF output power,

RFOP

PN Phase noise

SPT Transmitted spurious

(1)

TS_TR

TS_TR2

(1)

Transmitter wake-up time From FS to Tx ready. - 120 500 µs

Transmitter wake-up time From Stby to Tx ready. - 600 900 µs

Guaranteed by design and characterization

programmable with 8 steps
of typ. 3dB

Maximum power setting - +12.5 - dBm

Minimum power setting - -8.5 - dBm

Measured with a 600 kHz
offset, at the transmitter
output.
At any offset between
200 kHz and 600 kHz,
unmodulated carrier, Fdev
= 50 kHz.

- -112 - dBc/Hz

- - -47 dBc

Rev 8 – February 2013

Page 9 of 92 www.semtech.com

SX1211

d

(1)

(1)

WIRELESS & SENSING

2.4.4. Receiver

On the following table, fc and fo describe the bandwidth of the active channel filters as described in section 3.4.4.2.
All sensitivities are measured receiving a PN15 sequence, for a BER of 0.1.%

Table 8: Receiver Specification

Symbol Description Conditions Min Typ Max Unit

869 MHz, BR=25 kb/s, Fdev
=50 kHz, fc=100 kHz
869 MHz, BR=66.7 kb/s,

RFS_F Sensitivity (FSK)

Fdev=100 kHz, fc=200 kHz
915 MHz, BR=25 kb/s,
Fdev=50 kHz, fc=100 kHz
915 MHz, BR = 66.7 kb/s,
Fdev=100 kHz, fc=200 kHz
869 MHz, 2kb/s NRZ
fc-fo=50 kHz, fo=50 kHz
869 MHz, 16.7 kb/s NRZ

RFS_O Sensitivity (OOK)

fc-fo=100 kHz, fo=100 kHz
915 MHz, 2kb/s NRZ
fc-fo=50 kHz, fo=50 kHz
915 MHz, 16.7 kb/s NRZ
fc-fo=100 kHz, fo=100 kHz

CCR Co-channel rejection Modulation as wanted signal - -12 - dBc

Offset = 300 kHz, unwanted
tone is not modulated

ACR

Adjacent channel
rejection

Offset = 600 kHz, unwanted
tone is not modulated
Offset = 1.2 MHz, unwanted
tone is not modulated
Offset = 1 MHz,
unmodulated

BI Blocking immunity

Offset = 2 MHz,
unmodulated, no SAW
Offset = 10 MHz,
unmodulated, no SAW

RXBW_F

RXBW_O

IIP3

TS_RE
TS_RE2

(1,2)

(1,2)

Receiver bandwidth in
FSK mode
Receiver bandwidth in
OOK mode

r

Input 3

order intercept

point

Receiver wake-up time From FS to Rx ready - 280 500 µs

Receiver wake-up time From Stby to Rx ready - 600 900 µs

Single side BW
Polyphase Off
Single side BW
Polyphase On
Interferers at 1MHz and

1.950 MHz offset

200 kHz step - 400 - µs
1MHz step - 400 - µs
5MHz step - 460 - µs
7MHz step - 480 - µs
12MHz step - 520 - µs

TS_RE_HOP

Receiver hop time from
Rx ready to Rx ready with
a frequency hop

20MHz step - 550 - µs

27MHz step - 600 - µs
TS_RSSI RSSI sampling time From Rx ready - - 1/Fdev s
DR_RSSI RSSI dynamic Range Ranging from sensitivity - 70 - dB

(1)

Guaranteed by design and characterization

(2)

This reflects the whole receiver bandwidth, as described in sections 3.4.4.1 and 3.4.4.2

- -107 - dBm

- -103 - dBm

- -105 - dBm

- -101 - dBm

- -113 - dBm

- -106 - dBm

- -111 - dBm

- -105 - dBm

- 27 - dB

- 52 - dB

- 57 - dB

- -48 - dBm

- -37 - dBm

- -33 - dBm

50 - 250 kHz

50 - 400 kHz

- -28 - dBm

Rev 8 – February 2013

Page 10 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

2.4.5. Digital Specification

Conditions: Temp = 25 °C, VDD = 3.3 V, crystal frequency = 12.8 MHz, unless otherwise specified.

Table 9: Digital Specification

Symbol Description Conditions Min Typ Max Unit

VIH Digital input level high
VIL Digital input level low
VOH Digital output level high Imax=1mA 0.9*VDD - - V

VOL Digital output level low Imax=-1mA - - 0.1*VDD V
SCK_CONFIG SPI Config. clock frequency
SCK_DATA SPI Data clock frequency - - 1 MHz
T_DATA DATA hold and setup time 2 - - µs
T_MOSI_C MOSI setup time for SPI Config. 250 - - ns
T_MOSI_D MOSI setup time for SPI Data. 312 - - ns

T_NSSC_L

T_NSSD_L

T_NSSC_H NSS_CONFIG rising to falling edge. 500 - - ns
T_NSSD_H NSS_DATA rising to falling edge. 625 - - ns

NSS_CONFIG low to SCK rising edge.
SCK falling edge to NSS_CONFIG high.
NSS_DATA low to SCK rising edge.
SCK falling edge to NSS_DATA high.

500 - - ns

625 - - ns

Note: on pin 10 (XTAL_P) and 11 (XTAL_N), maximum voltages of 1.8V can be applied.

0.8*VDD - - V

- - 0.2*VDD V

- - 6 MHz

Rev 8 – February 2013

Page 11 of 92 www.semtech.com

WIRELESS & SENSING

3. Architecture Description

This section describes in depth the architecture of this ultra low-power transceiver:

SX1211

VR_PA

RFIO

XTAL_P

XTAL_M

LNA

XO

PA

I

Q

LO1 Rx

Frequency Synthesizer

LO1 Tx

LO2 Rx

I

Q

I

Q

LO2 Tx

LO2 Tx

RSSI

LO
Generator

LO1 Rx

I

LO2 Rx

Q

LO1 Tx

I

Q

I

LO2 Tx

Q

OOK

demod

FSK

demod

Waveform

generator

BitSync

Control

IRQ_0
IRQ_1

MOSI
MISO

SCK
NSS_CONFIG

NSS_DATA
CLKOUT
DATA

TEST(8:0)

PLL_LOCK

VR_VCO

VCO_P

LF_P

LF_M

VCO_M

VR_DIG

VR_1V

Figure 3: SX1211 Detailed Block Diagram

3.1. Power Supply Strategy

To provide stable sensitivity and linearity characteristics over a wide supply range, the SX1211 is internally
regulated. This internal regulated power supply structure is described below:

Rev 8 – February 2013

Page 12 of 92 www.semtech.com

WIRELESS & SENSING

Vbat

SX1211

1F
Y5V

Reg_top

1.4 V

VDD – Pin 26

2.1 – 3.6V

External Supply

Biasing :

-SPI

-Config. Registers

-POR

Reg_ana

1.0 V

Biasing analog

blocks

VR_1V

Pin 27

1F

Y5V

Reg_dig

1.0 V

Biasing digital

blocks

220nF

X7R

VR_DIG

Pin 28

Reg_VCO

0.85 V

Biasing :

-VCO circuit

-Ext. VCO
tank

100nF

X7R

VR_VCO

Pin 3

Reg_PA

1.80 V

Biasing :

-PA Driver

-PA choke
(ext)

47nF

X7R

VR_PA

Pin 29

Figure 4: Power Supply Breakdown

To ensure correct operation of the regulator circuit, the decoupling capacitor connection shown in Figure 4 is
required. These decoupling components are recommended for any design.

3.2. Frequency Synthesis Description

The frequency synthesizer of the SX1211 is a fully integrated integer-N type PLL. The PLL circuit requires only five
external components for the PLL loop filter and the VCO tank circuit.

3.2.1. Reference Oscillator

The SX1211 embeds a crystal oscillator, which provides the reference frequency for the PLL. The recommended
crystal specification is given in section 7.1.

3.2.2. CLKOUT Output

The reference frequency, or a sub-multiple of it, can be provided on CLKOUT (pin 19) by activating the bit
OSCParam_Clkout_on. The division ratio is programmed through bits OSCParam_Clkout_freq. The two
applications of the CLKOUT output are:
 To provide a clock output for a companion uC, 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-up.

 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 consumption of the SX1211, ensure that the CLKOUT signal is disabled when
unused.

Rev 8 – February 2013

Page 13 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

3.2.3. PLL Architecture

The crystal oscillator (XO) forms the reference oscillator of an Integer-N Phase Locked Loop (PLL), whose
operation is discussed in the following section. Figure 5 shows a block schematic of the SX1211 PLL. Here the
crystal reference frequency and the software controlled dividers R, P and S determine the output frequency of the
PLL.

÷75.(Pi+1)+Si

Fcomp

PFD

LF_M

Vtune

LF_P

VCO_M

XO

XT_M

÷(Ri+1)

XT_P

Figure 5: Frequency Synthesizer Description

The VCO tank inductors are connected on an external differential input. Similarly, the loop filter is also located
externally. However, there is an internal 8pF capacitance at VCO input that should be subtracted from the desired
loop filter capacitance.

The output signal of the VCO is used as the input to the local oscillator (LO) generator stage, illustrated in Figure 6.
The VCO frequency is subdivided and used in a series of up (down) conversions for transmission (reception).

VCO Output

LO

÷8

÷8

90°

90°

90°

LO1 Rx

I

LO2 Rx

Q

I

LO1 Tx

Q

I

LO2 Tx

Q

Receiver
LOs

Transmitter
LOs

Figure 6: LO Generator

LO

VCO_P

VR_VCO

3.2.4. PLL Tradeoffs

With an integer-N PLL architecture, the following criterion must be met to ensure correct operation:
 The comparison frequency, Fcomp, of the Phase Frequency Detector (PFD) input must remain higher than six

times the PLL bandwidth (PLLBW) to guarantee loop stability and to reject harmonics of the comparison
frequency Fcomp. This is expressed in the inequality:

PLLBW ≤

Fcomp

6

 However the PLLBW has to be sufficiently high to allow adequate PLL lock times
 Because the divider ration R determines Fcomp, it should be set close to 119, leading to Fcomp100 kHz

which will ensure suitable PLL stability and speed.

Rev 8 – February 2013

Page 14 of 92 www.semtech.com

SX1211

≤

≤

WIRELESS & SENSING

With the recommended Bill Of Materials (BOM) of the reference design of section 7.5.3, the PLL prototype is the
following:

 64  R  169
 S < P+1
 PLLBW = 15 kHz nominal
 Startup times and reference frequency spurs as specified.

3.2.5. Voltage Controlled Oscillator

The integrated VCO requires only two external tank circuit inductors. As the input is differential, the two inductors
should have the same nominal value. The performance of these components is important for both the phase noise
and the power consumption of the PLL. It is recommended that a pair of high Q factor inductors is selected. These
should be mounted orthogonally to other inductors (in particular the PA choke) to reduce spurious coupling
between the PA and VCO. In addition, such measures may reduce radiated pulling effects and undesirable
transient behavior, thus minimizing spectral occupancy. Note that ensuring a symmetrical layout of the VCO
inductors will further improve PLL spectral purity.

For best performance wound type inductors, with tight tolerance, should be used as described in section 7.5.3.

3.2.5.1. SW Settings of the VCO

To guarantee the optimum operation of the VCO over the SX1211’s frequency and temperature ranges, the
following settings should be programmed into the SX1211:

Target channel
(MHz)

Freq_band 10 00 01 10

Table 10: MCParam_Freq_band Setting

To ensure that the frequency band of operation may be accurately addressed by the R, P and S dividers of the
synthesizer, it is necessary to ensure that the VCO is correctly centered. Note that for the reference design (see
section 7.5) no centering is necessary. However, any deviation from the reference design may require the
optimization procedure, outlined below, to be implemented. This procedure is simplified thanks to the built-in VCO
trimming feature which is controlled over the SPI interface. This tuning does not require any RF test equipment,
and can be achieved by simply measuring Vtune, the voltage between pins 6 (LFM) and 7 (LFP).

The VCO is centered if the voltage is within the range:

Note that this measurement should be conducted when in transmit mode at the center frequency of the desired
band (for example ~867 MHz in the 863-870 MHz band), with the appropriate MCParam_Freq_band setting.

If this inequality is not satisfied then adjust the MCParam_VCO_trim bits from 00 whilst monitoring Vtune. This
allows the VCO voltage to be trimmed in + 60 mV increments. Should the desired voltage range be inaccessible,
the voltage may be adjusted further by changing the tank circuit inductance value. Note that an increase in
inductance will result in an increase Vtune.

863-

870

3.2.5.2. Trimming the VCO Tank by Hardware and Software

902-

915

915-

928

950-

960

mVVtune

150)(50

Rev 8 – February 2013

Page 15 of 92 www.semtech.com

SX1211

R

+

WIRELESS & SENSING

Note for mass production: The VCO capacitance is piece to piece dependant. As such, the optimization proposed
above should be verified on several prototypes, to ensure that the population is centered on 100 mV.

3.2.6. PLL Loop Filter

To adequately reject spurious components arising from the comparison frequency Fcomp, an external 2nd order
loop filter is employed.

RL1

LF_M

CL1 CL2

LF_P

Figure 7: Loop Filter

Following the recommendations made in section 3.2.4, the loop filter proposed in the reference design’s bill of
material on section 7.5.3 should be used. The loop filter settings are frequency band independent and are hence
relevant to all implementations of the SX1211.

3.2.7. PLL Lock Detection Indicator

The SX1211 also features a PLL lock detect indicator. This is useful for optimizing power consumption, by adjusting
the synthesizer wake up time (TS_FS), since the PLL startup time is lower than specified under nominal conditions.
The lock status can be read on bit IRQParam_PLL_lock, and must be cleared by writing a “1” to this same register.
In addition, the lock status can be reflected in pin 23 PLL_LOCK, by setting the bit IRQParam_Enable_lock_detect.

3.2.8. Frequency Calculation

As shown in Figure 5 the PLL structure comprises three different dividers, R, P and S, which set the output
frequency through the LO. A second set of dividers is also available to allow rapid switching between a pair of
frequencies: R1/P1/S1 and R2/P2/S2. These six dividers are programmed by six bytes of the register MCParam
from addresses 6 to 11.

3.2.8.1. FSK Mode

The following formula gives the relationship between the local oscillator, and R, P and S values, when using FSK
modulation.

9

=

,

,

fskFrf

FlofskFrf

8
9

Fxtal

=

()

[]

)175

SP

++

18

3.2.8.2. OOK Mode

Due to the manner in which the baseband OOK symbols are generated, the signal is always offset by the FSK
frequency deviation (Fdev - as programmed in MCParam_Freq_dev). Hence, the center of the transmitted OOK
signal is:

Rev 8 – February 2013

Page 16 of 92 www.semtech.com

SX1211

R

+

WIRELESS & SENSING

9

,,

8
9

txookFrf

=

,,

Consequently, in receive mode, due to the low intermediate frequency (Low-IF) architecture of the SX1211 the
frequency should be configured so as to ensure the correct low-IF receiver baseband center frequency, IF2.

9

,,

8
9

,,

rxookFrf

=

Note that from Section 3.4.4, it is recommended that IF2 be set to 100 kHz.

FdevFlotxookFrf

−=

Fxtal

()

[]

)175

−++

FdevSP

18

2

IFFlorxookFrf

−=

Fxtal

R

+

()

[]

−++

18

2)175

IFSP

Rev 8 – February 2013

Page 17 of 92 www.semtech.com

+⇒=

WIRELESS & SENSING

3.3. Transmitter Description

The SX1211 is set to transmit mode when MCParam_Chip_mode = 100.

SX1211

RFIO

Amplification

PA

RF

Second

up-conversion

I

Q

First up-conversion

I

Q

LO1 Tx

I

Q

IF

LO2 Tx

LO2 Tx

Interpolation

filters

DACs

Baseband

DDS

Waveform

generator

Data

Clock

Figure 8: Transmitter Architecture

3.3.1. Architecture Description

The baseband I and Q signals are digitally generated by a DDS whose digital to analog converters (DAC) followed
by two anti-aliasing low-pass filters transform the digital signal into analog in-phase (I) and quadrature (Q)
components whose frequency is the selected frequency deviation (Fdev).

1

Fdev

I(t)

Q(t)

Figure 9: I(t), Q(t) Overview

In FSK mode, the relative phase of I and Q is switched by the input data between -90° and +90° with continuous
phase. The modulation is therefore performed at this initial stage, since the information contained in the phase
difference will be converted into a frequency shift when the I and Q signals are up-converted in the first mixer
stage. This first up-conversion stage is duplicated to enhance image rejection. The FSK convention is such that:

''1''

FdevFrfDATA

FdevFrfDATA

−⇒=

Rev 8 – February 2013

''0''

Page 18 of 92 www.semtech.com

SX1211

=

B

WIRELESS & SENSING

In OOK mode, the phase difference between the I and Q channels is kept constant (independent of the transmitted
data). Thus, the first stage of up-conversion creates a fixed frequency signal at the low IF = Fdev (This explains
why the transmitted OOK spectrum is offset by Fdev).
OOK Modulation is accomplished by switching on and off the PA and PA regulator stages. By convention:

PAonDATA

⇒

''1''

PAoffDATA

⇒=

''0''

After the interpolation filters, a set of four mixers combines the I and Q signals and converts them into a pair of
complex signals at the second intermediate frequency, equal to 1/8 of the LO frequency, or 1/9 of the RF
frequency. These two new I and Q signals are then combined and up-converted to the final RF frequency by two
quadrature mixers fed by the LO signal. The signal is pre-amplified, and then the transmitter output is driven by a
final power amplifier stage.

3.3.2. Bit Rate Setting

In Continuous transmit mode, setting the Bit Rate is useful to determine the frequency of DCLK. As explained in
section 5.3.2, DCLK will trigger an interrupt on the uC each time a new bit has to be transmitted.

F

BR

=

[]

+

XTAL

)_(1*64 BRMCParamval

3.3.3. Alternative Settings

Bit rate, frequency deviation and TX interpolation filter settings are a function of the reference oscillator crystal
frequency, F
the correct reference oscillator frequency. Please contact your local Semtech representative for further details.

. Settings other than those programmable with a 12.8 MHz crystal can be obtained by selection of

XTAL

3.3.4. Fdev Setting in FSK Mode

The frequency deviation, Fdev, of the FSK transmitter is programmed through bits MCParam_Freq_dev:

F

Fdev

=

For correct operation the modulation index ß should be such that:

[]

+

β

XTAL

Fdev

2*2 ≥=

)__(1*32 devFreqMCParamval

R

It should be noted that for communications between a pair of SX1211s, that Fdev should be at least 33 kHz to
ensure a correct operation on the receiver side.

3.3.5. Fdev Setting in OOK Mode

Fdev has no physical meaning in OOK transmit mode. However, as has been shown - due to the DDS baseband
signal generation, the OOK signal is always offset by “-Fdev” (see formulas is section 3.2.8). It is suggested that
Fdev retains its default value of 100 kHz in OOK mode.

Rev 8 – February 2013

Page 19 of 92 www.semtech.com

SX1211

VR_PA

WIRELESS & SENSING

3.3.6. Interpolation Filter

After digital to analog conversion, both I and Q signals are smoothed by interpolation filters. This block low-pass
filters the digitally generated signal, and prevents the alias signals from entering the modulators. Its bandwidth can
be programmed with the register RXParam_InterpFiltTx, and should be set to:

⎡
⎢

⎣

Where Fdev is the programmed frequency deviation as set in MCParam_Freq_dev, and BR is the physical Bit Rate
of transmission.
Notes:
 Low interpolation filter bandwidth will attenuate the baseband I/Q signals thus reducing the power of the FSK

signal. Conversely, excessive bandwidth will degrade spectral purity.

 For the wideband FSK modulation, for example when operating in DTS mode, the recommended filter setting

can not be reached. However, the impact upon spectral purity will be negligible, due to the already wideband
channel.

3.3.7. Power Amplifier

⎤

+≅2*3BRFdevBW

⎥
⎦

The Power Amplifier (PA) integrated in the SX1211 operates under a regulated voltage supply of 1.8 V. The
external PA choke inductor is biased by an internal regulator output made available on pin 29 (VR_PA). Thanks to
these features, the PA output power is consistent over the power supply range. This is important for mobile
applications where this allows both predictable RF performance and battery life.

3.3.7.1. Rise and Fall Times Control

In OOK mode, the PA ramp times can be accurately controlled through the MCParam_PA_ramp register. Those
bits directly control the slew rate of VR_PA output (pin 29).

Table 11: PA Rise/Fall Times

MCParam_PA_ramp t

00 3 us 2.5 / 2 us
01 8.5 us 5 / 3 us
10 15 us 10 / 6 us
11 23 us 20 / 10 us

t

PA_OUT

(rise / fall)

Rev 8 – February 2013

Page 20 of 92 www.semtech.com

WIRELESS & SENSING

SX1211

DATA

VR_PA
[V]

PA Output
power

95 %

t

VR_PA

60 dB 60 dB

t

PA_OUT

t

VR_PA

t

PA_OUT

95 %

Figure 10: PA Control

3.3.7.2. Optimum Load Impedance

As the PA and the LNA front-ends in the SX1211 share the same Input/Output pin, they are internally matched to
approximately 50 .

Pmax-1dB circle

Max Power
Zopt = 30+j25 

Figure 11: Optimal Load Impedance Chart

Please refer to the reference design section for an optimized PA load setting.

Rev 8 – February 2013

Page 21 of 92 www.semtech.com

WIRELESS & SENSING

3.3.7.3. Suggested PA Biasing and Matching

SX1211

The recommended PA bias and matching circuit is illustrated below:

PA

VR_PA

RFIO

47nF

100nH

Low-pass and DC block

SAW

DC block

Antenna
port

Figure 12: Recommended PA Biasing and Output Matching

Please refer to section 7.5.3 of this document for the optimized matching arrangement for each frequency band.

3.3.8. Common Input and Output Front-End

The receiver and the transmitter share the same RFIO pin (pin 31). Figure 13 below shows the configuration of the
common RF front-end.
 In transmit mode, the PA and the PA regulator are active, with the voltage on the VR_PA pin equal to the

nominal voltage of the regulator (1.8 V). The external inductance is used to bias the PA.

 In receive mode, both PA and PA regulator are off and VR_PA is tied to ground. The external inductance LT1

is then used to bias the LNA.

To
Antenna

VR_PA

RFIO

Reg_PA

Rx_on

Figure 13: Front-end Description

PA

LNA

Rev 8 – February 2013

Page 22 of 92 www.semtech.com

q

WIRELESS & SENSING

3.4. Receiver Description

The SX1211 is set to receive mode when MCParam_Chip_mode = 011.

SX1211

IF1

Second down-

conversion

LO2 Rx

RSSI

OOK

demod

Bit

synchronizer

FSK

demod

Baseband, IF2 in OOK

Control logic

-Pattern recognition

-FIFO handler

-SPI interface

-Packet handler

LNA

RF

First down­conversion

LO1 Rx

Figure 14: Receiver Architecture

3.4.1. Architecture

The SX1211 receiver employs a super-heterodyne architecture. Here, the first IF is 1/9th of the RF frequency
(approximately 100MHz). The second down-conversion down-converts the I and Q signals to base band in the
case of the FSK receiver (Zero IF) and to a low-IF (IF2) for the OOK receiver.

Second

down-conversion

LO2

Rx

First

down-conversion

IF2=0
in FSK
mode

0

IF1

100MHz

Image

frequency

LO1 Rx

Channel

Frequencyl

Figure 15: FSK Receiver Setting

IF2<0

in FSK

mode
ual to fo

e

Second

down-conversion

0

IF1

100MHz

LO2 Rx

First

down-conversion

Image

frequency

LO1 Rx

Channel

Frequency

Figure 16: OOK Receiver Setting

After the second down-conversion stage, the received signal is channel-select filtered and amplified to a level
adequate for demodulation. Both FSK and OOK demodulation are available. Finally, an optional Bit Synchronizer
(BitSync) is provided, to be supply a synchronous clock and data stream to a companion uC in Continuous mode,

Rev 8 – February 2013

Page 23 of 92 www.semtech.com

SX1211

≤

≤

WIRELESS & SENSING

or to fill the FIFO buffers with glitch-free data in Buffered mode. The operation of the receiver is now described in
detail.

Note: Image rejection is achieved by the SAW filter.

3.4.2. LNA and First Mixer

In receive mode, the RFIO pin is connected to a fixed gain, common-gate, Low Noise Amplifier (LNA). The
performance of this amplifier is such that the Noise Figure (NF) of the receiver can be estimated to be 7 dB.

3.4.3. IF Gain and Second I/Q Mixer

Following the LNA and first down-conversion, there is an IF amplifier whose gain can be programmed from -

13.5 dB to 0 dB in 4.5 dB steps, via the register MCParam_IF_gain. The default setting corresponds to 0 dB gain,
but lower values can be used to increase the RSSI dynamic range. Refer to section 3.4.7 for additional information.

3.4.4. Channel Filters

The second mixer stages are followed by the channel select filters. The channel select filters have a strong
influence on the noise bandwidth and selectivity of the receiver and hence its sensitivity. Each filter comprises a
passive and active section.

3.4.4.1. Passive Filter

Each channel select filter features a passive second-order RC filter, with a bandwidth programmable through the
bits RXParam_PassiveFilt. As the wider of the two filters, its effect on the sensitivity is negligible, but its bandwidth
has to be setup instead to optimize blocking immunity. The value entered into this register sets the single side
bandwidth of this filter. For optimum performance it should be set to 3 to 4 times the cutoff frequency of the active
Butterworth (or polyphase) filter described in the next section.

,

FcBWFc *4*3

ButterFiltfilterpassivetButterfFil

3.4.4.2. Active Filter

The ’fine’ channel selection is performed by an active, third-order, Butterworth filter, which acts as a low-pass filter
for the zero-IF configuration (FSK), or a complex polyphase filter for the Low-IF (OOK) configuration. The
RXParam_PolypFilt_on bit enables/disables the polyphase filter.

Low-pass filter for FSK ( RXParam _PolyFilt_on=’’0’’)

-fC

Polyphase filter for OOK ( RXParam_PolyFilt_on=’’1’’ )

0

fC

Canceled side of

the polyphase filter

f

requency

f

-f

C

-f

o

0

requency

Figure 17: Active Channel Filter Description

Rev 8 – February 2013

Page 24 of 92 www.semtech.com

SX1211

=

+>−

WIRELESS & SENSING

As can be seen from Figure 17, the required bandwidth of this filter varies between the two demodulation modes.

 FSK mode: The 99% energy bandwidth of an FSK modulated signal is approximated to be:

⎡

%,99

FSK

The bits RXParam_ButterFilt set fc, the cutoff frequency of the filter. As we are in a Zero-IF configuration, the FSK
lobes are centered around the virtual “DC” frequency. The choice of fc should be such that the modulated signal
falls in the filter bandwidth, anticipating the Local Oscillator frequency drift over the operating temperature and
aging of the device:

*2

Please refer to the charts in section 3.4.5 for an accurate overview of the filter bandwidth vs. setting.

 OOK mode: The 99% energy bandwidth of an OOK modulated signal is approximated to be:

FdevBW

⎢
⎣

%,99

BW

The bits RXParam_PolypFilt_center set fo, the center frequency of the polyphase filter when activated. fo should
always be chosen to be equal to the low Intermediate Frequency of the receiver (IF2). This is why, in the GUI
described in section 7.2.1 of this document, the low IF frequency of the OOK receiver denoted IF2 has been
replaced by fo.

The following setting is recommended:

100

OOK

%,99

kHzfo

2

Tbit

PolypFiltRXParam

The value stored in RXParam_ButterFilt determines fc, the filter cut-off frequency. So the user should set fc
according to:

)(*2

Again, fc as a function of RXParam_ButterFilt is given in the section 3.4.6.

%,99

BR

⎤

+=2*2

LOBWfc+>

==

=

BR

.2

LOBWfofc

⎥
⎦

driftsFSK

"0011"_

driftsOOK

3.4.5. Channel Filters Setting in FSK Mode

Fc, the 3dB cutoff frequency of the Butterworth filter used in FSK reception, is programmed through the bit
RXParam_ButterFilt. However, the whole receiver chain influences this cutoff frequency. Thus the channel select
and resultant filter bandwidths are summarized in the following chart:

Rev 8 – February 2013

Page 25 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

450

400

350

300

250

200

150

Fc (3dB Cutoff) [kHz]

100

50

0

0246810121416

Butterworth Filter's BW, FSK

Val (RXParam_ButterFilt) [d]

Figure 18: Butterworth Filter's Actual BW

Table 37 suggests filter settings in FSK mode, along with the corresponding passive filter bandwidth and the
accepted tolerance on the crystal reference.

3.4.6. Channel Filters Setting in OOK Mode

The center frequency, fo, is always set to 100kHz. The following chart shows the receiver bandwidth when
changing RXParam_Butterfilt bits, whilst the polyphase filter is activated.

450

400

350

300

250

200

150

Fc-Fo with F o = 100 kHz [kHz ]

100

50

0

0246810121416

Figure 19: Polyphase Filter's Actual BW

Polyphase Filter's BW, OOK

Val (RXPara m_Butte r F ilt [d]
RXParam_PolypFil t="0011"

ActualBWTheoretical

BW

ActualBWTheoretical

BW

Table 38 suggests a few filter settings in OOK mode, along with the corresponding passive filter bandwidth and the
accepted tolerance on the crystal reference.

3.4.7. RSSI

After filtering, the In-phase and Quadrature signals are amplified by a chain of 11 amplifiers, each with 6dB gain.
The outputs of these amplifiers are used to evaluate the Received Signal Strength (RSSI).

3.4.7.1. Resolution and Accuracy

Whilst the RSSI resolution is 0.5 dB, the absolute accuracy is not expected to be better than +/- 3dB due to process
and external component variation. Higher accuracy whilst performing absolute RSSI measurements will require
additional calibration.

3.4.7.2. Acquisition Time

Rev 8 – February 2013

Page 26 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

In OOK mode, the RSSI evaluates the signal strength by sampling I(t) and Q(t) signals 16 times in each period of
the chosen IF2 frequency (refer to section 3.4.1). In FSK mode, the signals are sampled 16 times in each Fdev
period, Fdev being the frequency deviation of the companion transmitter. An average is then performed over a
sliding window of 16 samples. Hence, the RSSI output register RXParam_RSSI is updated 16 times in each Fdev
or IF2 period.

The following settings should be respected:
 FSK Mode: Ensure that the Fdev parameter (as described in MCParam_Fdev) remains consistent with the

actual frequency deviation of the companion transmitter.

 OOK reception: Ensure that the Fdev parameter (as described in MCParam_Fdev) is equal with the frequency

of I(t) and Q(t) signals, i.e. the second Intermediate Frequency, IF2, of the receiver (Note that this equals Fo,
the center frequency of the polyphase filter).

3.4.7.3. Dynamic Range

The dynamic range of the RSSI is over 70 dB, extending from the nominal sensitivity level. The IF gain setting
available in MCParam_IF_gain is used to achieve this dynamic range:

RSSI Response

180

160

140

120

100

80

RSSI_Val [0.5dB/bit]

60

40

20

0

-120 -100 -80 -60 -40 -20 0

IF_Gain=00 IF_Gain= 01 IF_Gain=10 IF_Gain=11

Pin [dBm]

Figure 20: RSSI Dynamic Range

The RSSI response versus input signal is independent of the receiver filter bandwidth. However in the absence of
any input signal, the minimum value directly reflects upon the noise floor of the receiver, which is dependant on the
filter bandwidth of the receiver.

3.4.7.4. RSSI IRQ Source

The SX1211 can also be used to detect a RSSI level above a pre-configured threshold. The threshold is set in
IRQParam_RSSI_irq_thresh and the IRQ status stored in IRQParam_RSSI_irq (cleared by writing a “1”).

An interrupt can be mapped to the IRQ0 or IRQ1 pins via bits IRQParam_Rx_stby_irq0 or
IRQParam_Rx_stby_irq1. Figure 21 shows the timing diagram of the RSSI interrupt source, with
IRQParam_RSSI_irq_thresh set to 28.

Rev 8 – February 2013

Page 27 of 92 www.semtech.com

WIRELESS & SENSING

=

SX1211

RXParam_RSSI_val(7:0)

IRQParam_RSSI_irq

24 26 27 30 25 20 20 20 18 22 20 22 34 33 33

Clear interrupt

Figure 21: RSSI IRQ Timings

3.4.8. Fdev Setting in Receive Mode

The effect of the Fdev setting is different between FSK and OOK modes:

3.4.8.1. FSK Rx Mode

In FSK mode the Fdev setting, as configured by MCParam_Freq_Dev, sets sampling frequencies on the receiver.
The user should make it consistent with the frequency deviation of the FSK signal that is received.

3.4.8.2. OOK Rx Mode

The frequency deviation Fdev, as described above, sets the sampling rate of the RSSI block. It is therefore
necessary to set Fdev to the recommended low-IF frequency, IF2, of 100 kHz:

=

1002

kHzIFFdev

=

devFreqMCParam

"00000011"__

3.4.9. FSK Demodulator

The FSK demodulator provides data polarity information, based on the relative phase of the input I and Q signals at
the baseband. Its outputs can be fed to the Bit Synchronizer to recover the timing information. The user can also
use the raw, unsynchronized, output of the FSK demodulator in Continuous mode.

The FSK demodulator of the SX1211 operates most effectively for FSK signals with a modulation index greater
than or equal to two:

β

Fdev

2*2≥=

BR

3.4.10. OOK Demodulator

The OOK demodulator performs a comparison of the RSSI output and a threshold value. Three different threshold
modes are available, programmed through the RXParam_OOK_thresh_type register.

The recommended mode of operation is the “Peak” threshold mode, illustrated below in Figure 22:

Rev 8 – February 2013

Page 28 of 92 www.semtech.com

WIRELESS & SENSING

RSSI
(dB)

Zoom

Zoom

Decay in dB as defined in

RXPAram_OOK_thresh_step

Period as defined in

RXParam_OOK_thresh_dec_period

Fixed 6dB difference

Figure 22: OOK Demodulator Description

SX1211

‘’Peak -6dB’’ Threshold

‘’Floor’’ threshold defined by
MCParam_OOK_floor_thresh

Noise floor of
receiver

Time

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
RXPAram_OOK_thresh_step every RXParam_OOK_thresh_dec_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” that is programmed
through the register MCParam_OOK_floor_thresh.

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 shall
be optimized accordingly.

3.4.10.1. Optimizing the Floor Threshold

MCParam_OOK_floor_thres 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.
 The bandwidth of the channel filters.

It is therefore important to note that the setting of MCParam_OOK_floor_thresh will be application dependant. The
following procedure is recommended to optimize MCParam_OOK_floor_thresh.

Rev 8 – February 2013

Page 29 of 92 www.semtech.com

WIRELESS & SENSING

SX1211

Set SX1211 in OOK Rx mode

Adjust Bit Rate, Channel filter BW

Default RXParam_OOK_thresh setting

No input signal

Continuous Mode

Glitch activity

on DATA ?

Optimization complete

Increment

MCParam_OOK_floor_thres

Monitor DATA pin (pin 20)

Figure 23: Floor Threshold Optimization

The new floor threshold value found during this test should be the value used for OOK reception with those receiver
settings.

Note that if the output signal on DATA is logic “1”, the value of MCParam_OOK_floor_thres is below the noise floor
of the receiver chain. Conversely, if the output signal on DATA is logic “1”, the value of MAParam_floor_thres is
several dB above the noise floor.

3.4.10.2. Optimizing OOK Demodulator Response 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 RXParam_OOK_thresh_step and
RXParam_OOK_thresh_dec_period can be optimized as described below for a given number of threshold
decrements per bit RXParam_OOK_thresh_dec_period:

 000 Æ once in each chip period (d)
 001 Æ once in 2 chip periods
 010 Æ once in 4 chip periods
 011 Æ once in 8 chip periods
 100 Æ twice in each chip period
 101 Æ 4 times in each chip period
 110 Æ 8 times in each chip period
 111 Æ 16 times in each chip period

For each decrement of RXParam_OOK_thresh_step:

 000 Æ 0.5 dB (d)
 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

Rev 8 – February 2013

Page 30 of 92 www.semtech.com

SX1211

π

WIRELESS & SENSING

3.4.10.3. 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 the MCParam_OOK_floor_thresh register (refer to section

3.4.10.1 for further information concerning optimization of the floor threshold).

 Average threshold: Data supplied by the RSSI block is averaged with the following cutoff frequency:

BR

00__

FcutoffcutoffOOKRXParam =⇒=

11__

FcutoffcutoffOOKRXParam =⇒=

In the first example, the higher cut-off frequency enables a sequence of up to 8 consecutive “0” or “1” to be
supported, whilst the lower cut-off frequency presented in the second example allows for the correct reception of up
to 32 consecutive “0” or “1”.

3.4.11. Bit Synchronizer

*8

BR

*32

π

The Bit Synchronizer (BitSync) is a block that provides a clean and synchronized digital output, free of glitches.

Raw demodulator

output

(FSK or OOK)

BitSync Output

To pin DATA and

DCLK in continuous

mode

DATA

DCLK
IRQ_1

Figure 24: BitSync Description

The BitSync can be disabled through the bits RXParam_Bitsync_off, and by holding pin IRQ1 low. However, for
optimum receiver performance, its use when running Continuous mode is strongly advised. With this option a
DCLK signal is present on pin IRQ_1.

The BitSync is automatically activated in Buffered and Packet modes. The bit synchronizer bit-rate is controlled by
MCParam_BR. For a given bit rate, this parameter is determined by:

F

BR

=

[]

XTAL

BRMCParam

_1*64 +

Rev 8 – February 2013

Page 31 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

To ensure correct operation of the Bit Synchronizer, the following conditions have to be satisfied:
 A preamble (0x55 or 0xAA) of three bytes is required for synchronization, the longer the synchronization the

better the packet success rate

 The subsequent payload bit stream must have at least one transition from '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%.

3.4.12. Alternative Settings

Bit Synchronizer and Active channel filter settings are a function of the reference oscillator crystal frequency, F
Settings other than those programmable with a 12.8 MHz crystal can be obtained by selection of the correct
reference oscillator frequency. Please contact your local Semtech representative for further details.

XTAL

3.4.13. Data Output

After OOK or FSK demodulation, the baseband signal is made available to the user on pin 20, DATA, when
Continuous mode is selected.

In Buffered and Packet modes, the data is retrieved from the FIFO through the SPI interface.

.

Rev 8 – February 2013

Page 32 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

4. Operating Modes

This section summarizes the settings for each operating mode of the SX1211, and explains the functionality
available and the timing requirements for switching between modes.

4.1. Modes of Operation

Table 12: Operating Modes

Mode MCParam_Chip_mode Active blocks

Sleep 000 SPI, POR
Standby 001 SPI, POR, Top regulator, digital regulator, XO, CLKOUT (if activated through

OSCParam_Clkout)
FS 010 Same + VCO regulator, all PLL and LO generation blocks
Receive 011 Same as FS mode + LNA, first mixer, IF amplifier, second mixer set, channel

filters, baseband amplifiers and limiters, RSSI, OOK or FSK demodulator,

BitSync and all digital features if enabled
Transmit 100 Same as FS mode + DDS, Interpolation filters, all up-conversion mixers, PA

driver, PA and external VR_PA pin output for PA choke.

4.2. Digital Pin Configuration vs. Chip Mode

Table 13 describes the state of the digital IOs in each of the above described modes of operation, regardless of the
data operating mode (Continuous, Buffered, or Packet).

Table 13: Pin Configuration vs. Chip Mode

Chip

……….Mode

Pin

NSS_CONFIG Input Input Input Input Input

NSS_DATA Input Input Input Input Input

MISO Input Input Input Input Input

MOSI Input Input Input Input Input
SCK Input Input Input Input Input
IRQ_0 High-Z Output (1) Output (1) Output Output
IRQ_1 High-Z Output (1) Output (1) Output Output
DATA Input Input Input Output Input
CLKOUT High-Z Output Output Output Output
PLL_LOCK High-Z Output (2) Output (2) Output (2) Output (2)

Notes:
(1): High-Z if Continuous mode is activated, else Output
(2): Output if PLL_lock_en = 1, else High-Z
(3): Valid logic states must be applied to inputs at all times to avoid unwanted leakage currents

Sleep
mode

Standby
mode

FS mode

Receive
mode

Transmit
mode

Comment

NSS_CONFIG has the priority over
NSS_DATA

Output only if NSS_CONFIG or
NSSDATA=’0’

Rev 8 – February 2013

Page 33 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5. Data Processing

5.1. Overview

5.1.1. Block Diagram

Figure 25, illustrates the SX1211 data processing circuit. Its role is to interface the data to/from the
modulator/demodulator and the uC access points (SPI, IRQ and DATA pins). It also controls all the configuration
registers.

The circuit contains several control blocks which are described in the following paragraphs.

Tx/Rx

Data

Rx

Tx

SYNC
RECOG.

PACKET
HANDLER

SX1211

CONTROL

FIFO
(+SR)

SPI

CONFIG

DATA

DATA

IRQ_0

IRQ_1

NSS_DATA
SCK
MOSI
MISO

Figure 25: SX1211’s Data Processing Conceptual View

The SX1211 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 SX1211 has three different data operation modes selectable by the user:
 Continuous mode: each bit transmitted or received is accessed in real time at the DATA pin. This mode may be

used if adequate external signal processing is available.

 Buffered mode: each byte transmitted or received is stored in a FIFO and accessed via the SPI bus. uC

processing overhead is hence significantly reduced compared to Continuous mode operation. The packet
length is unlimited.

 Packet mode (recommended): user only provides/retrieves payload bytes to/from the FIFO. The packet is

automatically built with preamble, Sync word, and optional CRC, DC free encoding and the reverse operation is
performed in reception. The uC processing overhead is hence reduced further compared to Buffered mode.
The maximum payload length is limited to the maximum FIFO limit of 64 bytes

Rev 8 – February 2013

Page 34 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

Table 14: Data Operation Mode Selection

MCParam_Data_mode Data Operation Mode

00 Continuous
01 Buffered
1x Packet

Each of these data operation modes is described fully in the following sections.

5.2. Control Block Description

5.2.1. SPI Interface

5.2.1.1. Overview

As illustrated in the Figure 26 below, the SX1211’s SPI interface consists of two sub blocks:

 SPI Config: used in all data operation modes to read and write the configuration registers which control all the

parameters of the chip (operating mode, bit rate, etc...)

 SPI Data: used in Buffered and Packet mode to write and read data bytes to and from the FIFO. (FIFO

interrupts can be used to manage the FIFO content.)

SX1211

Config.

Config.

Registers

Registers

NSS_CONFIG

SPI

CONFIG

(slave)

MOSI
MISO
SCK

NSS_CONFIG
MOSI
MISO
SCK
NSS_DATA

µ C

FIFO

Figure 26: SPI Interface Overview and uC Connections

Both interfaces are configured in slave mode whilst the uC is configured as the master. They have separate
selection pins (NSS_CONFIG and NSS_DATA) but share the remaining pins:

 SCK (SPI Clock): clock signal provided by the uC
 MOSI (Master Out Slave In): data input signal provided by the uC
 MISO (Master In Slave Out): data output signal provided by the SX1211

As described below, only one interface can be selected at a time with NSS_CONFIG having the priority:

SPI
DATA
(slave)

NSS_DATA

(master)

Rev 8 – February 2013

Page 35 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

Table 15: Config vs. Data SPI Interface Selection

NSS_DATA NSS_CONFIG SPI Interface

0 0 Config
0 1 Data
1 0 Config
1 1 None

The following paragraphs describe how to use each of these interfaces.

5.2.1.2. SPI Config

 Write Register
To write a value into a configuration register the timing diagram below should be carefully followed by the uC.
The register’s new value is effective from the rising edge of NSS_CONFIG.

NSS_CONFIG (In)

SCK (In)

1 5 4 3 2 6 987

10

11 12 13 14 15 16

New value at

address A1

MOSI (In)

MISO (Out)

start

HZ

(input)

x x x x x x x

* when writing the new value at address A1, the current content of A1 can be read by the uC.

A(4) A(3) A(2) A(1) D(7) D(6) D(5) D(4) D(3) D(2) D(1) D(0)

rw

Address = A1

x

(In)/(Out) refers to SX1211 side

A(0)

stop

Current value at

address A1*

D(7) D(6) D(5) D(4) D(3) D(2) D(1)

D(0)

HZ

(input)

Figure 27: Write Register Sequence

Note that when writing more than one register successively, it is not compulsory to toggle NSS_CONFIG back high
between two write sequences. The bytes are alternatively considered as address and value. In this instance, all
new values will become effective on rising edge of NSS_CONFIG.
 Read Register
To read the value of a configuration register the timing diagram below should be carefully followed by the uC.

Rev 8 – February 2013

Page 36 of 92 www.semtech.com

WIRELESS & SENSING

t

t

d

NSS_CONFIG (In)

SCK (In)

1 5 4 3 2 6 987

SX1211

10

11 12 13 14 15 16

MOSI (In)

MISO (Out)

HZ
(input)

start A(4) A(3) A(2) A(1)

rw A(0)

Address = A1

x

x x x x x x x

xxxxx

stop

Current value at

address A1

D(7) D(6) D(5) D(4) D(3) D(2) D(1)

x

x x

D(0)

HZ
(inpu

Figure 28: Read Register Sequence

Note that when reading more than one register successively, it is not compulsory to toggle NSS_CONFIG back
high between two read sequences. The bytes are alternatively considered as address and value.

5.2.1.3. SPI Data

 Write Byte (before/during Tx)
To write bytes into the FIFO the timing diagram below should be carefully followed by the uC.

NSS_DATA (In)

1

3

2

5

4

6 87 1 5

432 6

8

7

SCK (In)

MOSI (In)

MISO (Out)

HZ
(input)

s

1

byte written

D1(6) D1(5) D1(4) D1(3) D1(2) D1(1) D2(7) D2(6) D2( 5) D2(4) D2(3) D2(2) D2(1) D2(0)D1(0)D1(7)

x

x x x x x x x x x x x x x x x x

x

HZ

(input)

n

2

byte written

HZ
(input)

Figure 29: Write Bytes Sequence (ex: 2 bytes)

Note that it is compulsory to toggle NSS_DATA back high between each byte written.
The byte is pushed into the FIFO on the rising edge of NSS_DATA

Rev 8 – February 2013

Page 37 of 92 www.semtech.com

t

d

WIRELESS & SENSING

 Read Byte (after/during Rx)
To read bytes from the FIFO the timing diagram below should be carefully followed by the uC.

1

3

2

5

4

6 87 1 5

432 6

87

SX1211

NSS_DATA (In)

SCK (In)

MOSI (In)

MISO (Out)

HZ
(input)

x x x x x x x x x x x x x x x x

s

1

byte read

D1(6) D1(5) D1(4) D1(3) D1(2) D1(1) D2(7) D2(6) D2(5) D2(4) D2(3) D2(2) D2(1) D2(0)D1(0)

D1(7)

HZ
(input)

x

n

2

byte read

HZ
(input)

Figure 30: Read Bytes Sequence (ex: 2 bytes)

Note that it is compulsory to toggle NSS_DATA back high between each byte read.

5.2.2. FIFO

5.2.2.1. Overview and Shift Register (SR)

In Buffered and Packet modes 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 Data interface and provides several
interrupts for transfer management.

The FIFO is 1 byte (8 bits) 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.

byte1

FIFO

byte0

Data Tx/Rx

1

MSB

8

SR (8bits)

LSB

Figure 31: FIFO and Shift Register (SR)

5.2.2.2. Size Selection

The FIFO width is programmable, to 16, 32, 48 or 64 bytes via MCParam_Fifo_size

Rev 8 – February 2013

Page 38 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.2.2.3. Interrupt Sources and Flags

All interrupt sources and flags are configured in the IRQParam section of the configuration register, with the
exception of Fifo_threshold :
 /Fifoempty: /Fifoempty 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, /Fifoempty is updated on NSS_DATA falling edge, i.e. when
/Fifoempty is updated to low state the currently started read operation must be completed. In other words,
/Fifoempty state must be checked after each read operation for a decision on the next one (/Fifoempty = 1:
more byte(s) to read; /Fifoempty = 0: no more byte to read).

 Write_byte: Write_byte interrupt source goes high for 1 bit period each time a new byte is transferred from the

SR to the FIFO (i.e. each time a new byte is received)

 Fifofull: Fifofull interrupt source is high when the last FIFO byte, i.e. the whole FIFO, is full. Otherwise it is low.
 Fifo_overrun_clr: Fifo_overrun_clr flag 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.

 Tx_done: Tx_done interrupt source goes high when FIFO is empty and the SR’s last bit has been send to the

modulator (i.e. the last bit of the packet has been sent). One bit period delay is required after the rising edge of
Tx_done to ensure correct RF transmission of the last bit. In practice this may not require special care in the
uC software due to IRQ processing time.

 Fifo_threshold: Fifo_threshold interrupt source’s behavior depends on the running mode (Tx, Rx or Stby mode)

and the threshold itself can be programmed via MCParam_Fifo_thresh (B value). This behavior is illustrated in
Figure 32.

IRQ source

1

0

Tx

Rx & Stby

B

B+1 B+2

# of bytes in FIFO

Figure 32: FIFO Threshold IRQ Source Behavior

5.2.2.4. FIFO Clearing

Table 16 below summarizes the status of the FIFO when switching between different modes

Table 16: Status of FIFO when Switching Between Different Modes of the Chip

From To FIFO Status Comments

Stby Tx

Stby Rx Cleared
Rx Tx Cleared
Rx Stby Not cleared In Packet & Buffered modes FIFO can be read in Stby after Rx
Tx Rx Cleared
Tx Stby Not cleared
Any Sleep Cleared

Cleared In Buffered mode, FIFO cannot be written in Stby before Tx
Not cleared In Packet mode, FIFO can be written in Stby before Tx

Rev 8 – February 2013

Page 39 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.2.3. Sync Word Recognition

5.2.3.1. Overview

Sync word recognition (also called Pattern recognition in previous products) is activated by setting
RXParam_Sync_on. The bit synchronizer must also be activated.

The block behaves like a shift register; it continuously compares the incoming data with its internally programmed
Sync word and asserts the Sync IRQ source on each occasion that a match is detected. This is illustrated in Figure

33.

Rx DATA
(NRZ)

DCLK

SYNC

Bit N-x =

Sync_value[x]

Bit N-1 =

Sync_value[1]

Bit N =

Sync_value[0]

Figure 33: Sync Word Recognition

During the comparison of the demodulated data, the first bit received is compared with bit 7 (MSB) of byte at
address 22 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.

5.2.3.2. Configuration

 Size: Sync word size can be set to 8, 16, 24 or 32 bits via RXParam_Sync_size. 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 to 0, 1, 2 or 3 via

RXParam_Sync_tol.

 Value: The Sync word value is configured in SYNCParam_Sync_value. In Packet mode this field is also used

for Sync word generation in Tx mode.

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.

Rev 8 – February 2013

Page 40 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.3. Continuous Mode

5.3.1. General Description

As illustrated in Figure 34, in Continuous mode the NRZ data to (from) the (de)modulator is directly accessed by
the uC on the bidirectional DATA pin (20). The SPI Data, FIFO and packet handler are thus inactive.

SX1211

CONTROL

DATA

IRQ_0
IRQ_1(DCLK)

SPI

NSS_CONFIG

CONFIG

SCK
MOSI

MISO

Data

Tx/Rx

Rx

Datapath

SYNC
RECOG.

Figure 34: Continuous Mode Conceptual View

5.3.2. Tx Processing

In Tx mode, a synchronous data clock for an external uC is provided on IRQ_1 pin. Its timing with respect to the
data is illustrated in Figure 35. DATA is internally sampled on the rising edge of DCLK so the uC can change logic
state anytime outside the greyed out setup/hold zone.

The use of DCLK is compulsory in FSK and optional in OOK.

T_DATAT_DAT A

DATA (NRZ)

Rev 8 – February 2013

DCLK

Figure 35: Tx Processing in Continuous Mode

Page 41 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.3.3. 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 DATA and IRQ_1 pins. DATA is sampled on the rising edge of DCLK and updated on the falling edge as
illustrated in Figure 36.

DATA (NRZ)

DCLK

Figure 36: Rx Processing in Continuous Mode

Note that in Continuous mode it is always recommended to enable the bit synchronizer to clean the DATA signal
even if the DCLK signal is not used by the uC. (bit synchronizer is automatically enabled in Buffered and Packet
mode).

5.3.4. Interrupt Signals Mapping

The tables below give the description of the interrupts available in Continuous mode.

Rx_stby_irq_0

00 (d) Sync

IRQ_0

01 RSSI
1x -

IRQ_1

Table 17: Interrupt Mapping in Continuous Rx Mode

Rx

DCLK

Note: In Continuous mode, no interrupt is available in Stby mode

IRQ_0
IRQ_1

Tx

-

DCLK

Table 18: Interrupt Mapping in Continuous Tx Mode

Rev 8 – February 2013

Page 42 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.3.5. uC Connections

SX1211

DATA

IRQ_0

IRQ_1 (DCLK)

NSS_CONFIG

SCK
MOSI
MISO

Figure 37: uC Connections in Continuous Mode

Note that some connections may not be needed depending on the application:

 IRQ_0: if Sync and RSSI interrupts are not used. In this case, leave floating.
 IRQ_1: if the chip is never used in Tx FSK mode (DCLK connection is not compulsory in Rx and Tx OOK

modes). In this case, leave floating.

 MISO: if no read register access is needed. In this case, pull-up to VDD through a 100 k resistor.

In addition, NSS_DATA pin (unused in continuous mode) should be pulled-up to VDD through a 100 k resistor.
Please refer to Table 13 for SX1211’s pins configuration

uC

5.3.6. Continuous Mode Example

 Configure all data processing related registers listed below appropriately. In this example we assume that both

Bit synchronizer and Sync word recognition are on.

Table 19: Relevant Configuration Registers in Continuous Mode (data processing related only)

MCParam

IRQParam

RXParam

SYNCParam

Tx Rx

Data_mode_x X X Defines data operation mode (Æ Continuous)

Rx_stby_irq_0 X Defines IRQ_0 source in Rx mode

Sync_on X Enables Sync word recognition

Sync_size X Defines Sync word size

Sync_tol X Defines the error tolerance on Sync word recognition

Sync_value X Defines Sync word value

Tx Mode:

 Go to Tx mode (and wait for Tx to be ready, see Figure 50)
 Send all packet’s bits on DATA pin synchronously with DCLK signal provided on IRQ_1
 Go to Sleep mode

Rx Mode:
 Program Rx interrupts: IRQ_0 mapped to Sync (Rx_stby_irq_0=”00”) and IRQ_1 mapped to DCLK (Bit

synchronizer enabled)

 Go to Rx mode (note that Rx is not ready immediately, see Figure 49)
 Wait for Sync interrupt
 Get all packet bits on DATA pin synchronously with DCLK signal provided on IRQ_1
 Go to Sleep mode

Description

Rev 8 – February 2013

Page 43 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.4. Buffered Mode

5.4.1. General Description

As illustrated in Figure 38, for Buffered mode operation 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 Data interface. This frees the uC for other
tasks between processing data from the SX1211, furthermore it simplifies software development and reduces uC
performance requirements (speed, reactivity). Note that in this mode the packet handler stays inactive.

An important feature is also the ability to empty the FIFO in Stby mode, ensuring low power consumption and
adding greater software flexibility.

SX1211

IRQ_0

IRQ_1

NSS_CONFIG

NSS_DATA
SCK
MOSI
MISO

Data

Rx

Tx

Datapath

SYNC

RECOG.

CONTROL

SPI

CONFIG

FIFO

(+SR)

DATA

Figure 38: Buffered Mode Conceptual View

Note that Bit Synchronizer is automatically enabled in Buffered mode. The Sync word recognition must be enabled
(RXParam_Sync_on=1) independently of the FIFO filling method selected (IRQParam_Fifo_fill_method).

5.4.2. Tx Processing

After entering Tx in Buffered mode, the chip expects the uC to write into the FIFO, via the SPI Data interface, all the
data bytes to be transmitted (preamble, Sync word, payload...).

Actual transmission of first byte will start either when the FIFO is not empty (i.e. first byte written by the uC) or when
the FIFO is full depending on bit IRQParam_Tx_start_irq_0.

In Buffered mode the packet length is not limited, i.e. as long as there are bytes inside the FIFO they are sent.
When the last byte is transferred to the SR, /Fifoempty IRQ source is asserted to warn the uC, at that time FIFO
can still be filled with additional bytes if needed.

When the last bit of the last byte has left the SR (i.e. 8 bit periods later), the Tx_done interrupt source is asserted
and the user can exit Tx mode after waiting at least 1 bit period from the last bit processed by modulator.

Rev 8 – February 2013

Page 44 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

If the transmitter is switched off (for example due to entering another chip mode) during transmission it will stop
immediately, even if there is still unsent data.

Figure 39 illustrates Tx processing with a 16 byte FIFO depth and Tx_start_irq_0=0. Please note that in this
example the packet length is equal to FIFO size, but this does not need to be the case, the uC can use the FIFO
interrupts anytime during Tx to manage FIFO contents and write additional bytes.

Start condition
(Cf. Tx_start_irq_0)

Fifofull

/Fifoempty

Tx_done

15

FIFO

0

Data Tx

(from SR)

from

SPI Data

b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1

b0

XXX

b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11

b14 b15b12 b13

XXX

Figure 39: Tx processing in Buffered Mode (FIFO size = 16, Tx_start_irq_0=0)

5.4.3. Rx Processing

After entering Rx in Buffered mode, the chip requires the uC to retrieve the received data from the FIFO. The FIFO
will actually start being filled with received bytes either; when a Sync word has been detected (in this case only the
bytes following the Sync word are filled into the FIFO) or when the Fifo_fill bit is asserted by the user - depending
on the state of bit, IRQParam_Fifo_fill_method.
In Buffered mode, the packet length is not limited i.e. as long as Fifo_fill is set, the received bytes are shifted into
the FIFO.

The uC software must therefore manage the transfer of the FIFO contents by interrupt and ensure reception of the
correct number of bytes. (In this mode, even if the remote transmitter has stopped, the demodulator will output
random bits from noise)

When the FIFO is full, Fifofull IRQ source is asserted to alert the uC, that at that time, the FIFO can still be unfilled
without data loss. If the FIFO is not unfilled, once the SR is also full (i.e. 8 bits periods later) Fifo_overrun_clr is
asserted and SR’s content is lost.

Figure 40 illustrates an Rx processing with a 16 bytes FIFO size and Fifo_fill_method=0. Please note that in the
illustrative example of section 5.4.6, the uC does not retrieve any byte from the FIFO through SPI Data, causing
overrun.

Rev 8 – February 2013

Page 45 of 92 www.semtech.com

WIRELESS & SENSING

Data Rx

“noisy” data

(to SR)

Start condition
(Cf. Fifo_fill_method)

/Fifoempty

Fifofull

Fifo_overrun_clr

Write_byte

FIFO

15

0

Figure 40: Rx Processing in Buffered Mode (FIFO size=16, Fifo_fill_method=0)

Preamble

Sync

SX1211

b0

b1 b2 b3

b1

b0

b4 b5 b6 b7 b8

b4

b3

b2

b9 b10 b11

b8

b7

b6

b5

b11

b10

b9

b14 b15b12 b13

b13

b12

b14

b16

b15

5.4.4. Interrupt Signals Mapping

The tables below describe the interrupts available in Buffered mode.

Rx_stby_irq_x

00 (d) - -

IRQ_0

01 Write_byte ­10 /Fifoempty /Fifoempty
11 Sync -

00 (d) - -

IRQ_1

01 Fifofull Fifofull
10 RSSI ­11 Fifo_threshold Fifo_threshold

Rx Stby

Table 20: Interrupt Mapping in Buffered Rx and Stby Modes

IRQ_0

Tx_irq_1=0 (d) Fifofull

IRQ_1

Tx_irq_1=1 Tx_done

Table 21: Interrupt Mapping in Buffered Tx Mode

/Fifoempty

Tx

Rev 8 – February 2013

Page 46 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.4.5. uC Connections

SX1211

IRQ_0
IRQ_1

NSS_CONFIG

NSS_DATA

SCK
MOSI
MISO

Figure 41: uC Connections in Buffered Mode

Note that depending upon the application, some uC connections may not be needed:

 IRQ_0: if none of the relevant IRQ sources are used. In this case, leave floating.
 IRQ_1: if none of the relevant IRQ sources are used. In this case, leave floating.
 MISO: if no read register access is needed and the chip is used in Tx mode only. In this case, pull up to VDD

through a 100 k resistor.

In addition, DATA pin (unused in buffered mode) should be pulled-up to VDD through a 100 k resistor.
Please refer to Table 13 for the SX1211’s pin configuration.

uC

5.4.6. Buffered Mode Example

 Configure all data processing related registers listed below appropriately. In this example we assume Sync

word recognition is on and Fifo_fill_method=0.

MCParam

IRQParam

RXParam

SYNCParam

Fifo_fill_method X Defines FIFO filling method

Tx Rx

Data_mode_x X X Defines data operation mode (ÆBuffered)

Fifo_size X X Defines FIFO size

Fifo_thresh X X Defines FIFO threshold

Rx_stby_irq_0 X Defines IRQ_0 source in Rx & Stby modes
Rx_stby_irq_1 X Defines IRQ_1 source in Rx & Stby modes

Tx_irq_1 X Defines IRQ_1 source in Tx mode

Fifo_fill X Controls FIFO filling status

Tx_start_irq_0 X Defines Tx start condition and IRQ_0 source

Sync_size X Defines Sync word size

Sync_tol X Defines the error tolerance on Sync word detection

Sync_value X Defines Sync word value

Table 22: Relevant Configuration Registers in Buffered Mode (data processing related o nly)

Tx Mode:
 Program Tx start condition and IRQs: Start Tx when FIFO is not empty (Tx_start_irq_0=1) and IRQ_1 mapped

to Tx_done (Tx_irq_1=1)

 Go to Tx mode (and wait for Tx to be ready, see Figure 50)

Description

Rev 8 – February 2013

Page 47 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

 Write packet bytes into FIFO. Tx starts when the first byte is written (Tx_start_irq_0=1). We assume the FIFO is

being filled via SPI Data faster than being unfilled by SR.

 Wait for Tx_done interrupt (+1 bit period)
 Go to Sleep mode

Rx Mode:
 Program Rx/Stby interrupts: IRQ_0 mapped to /Fifoempty (Rx_stby_irq_0=10) and IRQ_1 mapped to

Fifo_threshold (Rx_stby_irq_1=11). Configure Fifo_thresh to an appropriate value (ex: to detect packet end if
its length is known)

 Go to Rx mode (note that Rx is not ready immediately, Cf section 7.3.1).
 Wait for Fifo_threshold interrupt (i.e. Sync word has been detected and FIFO filled up to the defined threshold).
 If it is packet end, go to Stby (SR’s content is lost).
 Read packet bytes from FIFO until /Fifoempty goes low (or correct number of bytes is read).
 Go to Sleep mode.

Rev 8 – February 2013

Page 48 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

5.5. Packet Mode

5.5.1. General Description

Similar to Buffered mode operation, 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 Data interface.

In addition, the SX1211’s packet handler performs several packet oriented tasks such as Preamble and Sync word
generation, CRC calculation/check, whitening/dewhitening of data, address filtering, etc. This simplifies still further
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 Stby mode, ensuring optimum power consumption
and adding more flexibility for the software.

SX1211

IRQ_0

IRQ_1

NSS_CONFIG

NSS_DATA
SCK
MOSI
MISO

Data

Rx

Tx

Datapath

SYNC

RECOG.

PACKET

HANDLER

CONTROL

SPI

CONFIG

FIFO

(+SR)

DATA

Figure 42: Packet Mode Conceptual View

Note that Bit Synchronizer and Sync word recognition are automatically enabled in Packet mode.

5.5.2. Packet Format

Two types of packet formats are supported: fixed length and variable length, selectable by the
PKTParam_Pkt_format bit. The maximum size of the payload is limited by the size of the FIFO selected (16, 32, 48
or 64 bytes).

5.5.2.1. Fixed Length Packet Format

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 set by the PKTParam_Payload_length register and is limited by the size of the FIFO
selected.

Rev 8 – February 2013

Page 49 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

The length stored in this register 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 in Figure 43. It contains the following fields:

 Preamble (1010...).
 Sync word (Network ID).
 Optional Address byte (Node ID).
 Message data.
 Optional 2-bytes CRC checksum.

Optional DC free data coding

CRC checksum calculation

Preamble

1 to 4 bytes

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

Sync Word

1 to 4 bytes

Address

byte

Message

0 to (FIFO size) bytes

Payload/FIFO

CRC

2-bytes

Figure 43: Fixed Length Packet Format

5.5.2.2. Variable Length Packet Format

This mode is necessary 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 in Figure 44, is given by the first byte of the
FIFO and is limited only by the width of the FIFO selected. 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 in Figure 44. 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.

Rev 8 – February 2013

Page 50 of 92 www.semtech.com

WIRELESS & SENSING

SX1211

Optional DC free data coding

CRC checksum calculation

Length

Sync Word

1 to 4 bytes

Preamble

1 to 4 bytes

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

Length

byte

Address

byte

Payload/FIFO

Message

0 to (FIFO size - 1) bytes

CRC

2-bytes

Figure 44: Variable Length Packet Format

5.5.3. Tx Processing

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 to be provided by the user in the FIFO.

Assuming that the chip is already in Tx mode then, depending on IRQParam_Tx_start_irq_0 bit, packet
transmission (starting with programmed preamble) will start either after the first byte is written into the FIFO
(Tx_start_irq_0=1) or after the number of bytes written reaches the user defined threshold (Tx_start_irq_0=0). The
FIFO can also be fully or partially filled in Stby mode via PKTParam_Fifo_stby_access. In this case, the start
condition will only be checked when entering Tx mode.

At the end of the transmission (Tx_done = 1), the user must explicitly exit Tx mode if required. (e.g. back to Stby)

Note that while in Tx mode, before and after actual packet transmission (not enough bytes or Tx_done), additional
preamble bytes are automatically sent to the modulator. When the start condition is met, the current additional
preamble byte is completely sent before the transmission of the next packet (i.e. programmed preamble) is started.

5.5.4. Rx Processing

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 CRC_status bit and CRC_OK IRQ source.

Only the payload (including optional address and length fields) is made available in the FIFO.

Payload_ready and CRC_OK interrupts (the latter only if CRC is enabled) can be generated to indicate the end of
the packet reception.

Rev 8 – February 2013

Page 51 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

By default, if the CRC check is enabled and fails for the current packet, then the FIFO is automatically cleared and
neither of the two interrupts are generated and new packet reception is started. This autoclear function can be
disabled via PKTParam_CRC_autoclr bit and, in this case, even if CRC fails, the FIFO is not cleared and only
Payload_ready IRQ source is asserted.

Once fully received, the payload can also be fully or partially retrieved in Stby mode via
PKTParam_Fifo_stby_access. At the end of the reception, although the FIFO automatically stops being filled, it is
still up to the user to explicitly exit Rx mode if required. (e.g. go to Stby to get payload). FIFO must be empty for a
new packet reception to start.

5.5.5. Packet Filtering

SX1211’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.

5.5.5.1. Sync Word Based

Sync word filtering/recognition is automatically enabled in Packet mode. It 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) via RXParam_Sync_size, RXParam_Sync_tol and SYNCParam configuration
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 Sync IRQ source is asserted.

5.5.5.2. Address Based

Address filtering can be enabled via the PKTParam_Adrs_filt bits. It adds another level of filtering, above Sync
word, 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).

Three address based filtering options are available:
 Adrs_filt = 01: Received address field is compared with internal register Node_Adrs. If they match then the

packet is accepted and processed, otherwise it is discarded.

 Adrs_filt = 10: Received address field is compared with internal register Node_Adrs and the constant 0x00. 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.

 Adrs_filt = 11: Received address field is compared with internal register Node_Adrs and the constants 0x00 &

0xFF. If any of the three matches, then the received packet is accepted and processed, otherwise it is
discarded. These additional checks with constants are useful for implementing broadcast commands of all
nodes.

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, Node_Adrs and Adrs_filt 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.

5.5.5.3. Length Based

In variable length Packet mode, PKTParam_Payload_length must be programmed with the maximum length
permitted. If received length byte is smaller than this maximum then the packet is accepted and processed,
otherwise it is discarded.

Rev 8 – February 2013

Page 52 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

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 PKTParam_Payload_length to the value of the FIFO
size selected.

5.5.5.4. CRC Based

The CRC check is enabled by setting bit PKTParam_CRC_on. 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 the PKTParam_CRC_status bit and CRC_OK IRQ source.

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 PKTParam_CRC_autoclr bit and in this case, even if CRC fails, the FIFO is not
cleared and only Payload_ready 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 in Figure 45. This implementation also detects errors due to
leading and trailing zeros.

16

data input

X

CRC Polynomial =X

X

14

15

X

13

X

12

X

11

* * *

+ X

X

12

5

+ X5 + 1

X

4

* * *

X

0

Figure 45: CRC Implementation

5.5.6. 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. Please note that only one of the two methods should be enabled at a time.

5.5.6.1. Manchester Encoding

Manchester encoding/decoding is enabled by setting bit PKTParam_Manchester_on 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.

Rev 8 – February 2013

Page 53 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

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 MCParam_BR (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.

1/BR 1/BR

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
User/NRZ bits
Manchester ON

... 1 1 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 ...

... 1 1 1 0 1 0 0 1 0 0 1 1 ...

5.5.6.2. 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 datarate i.e. actual
bit rate is not halved.

The whitening/de-whitening process is enabled by setting bit PKTParam_Whitening_on. 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 in Figure 47. 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.

...Sync Payload...

Figure 46: Manchester Encoding/Decoding

LFSR Polynomial =X9 + X

5

+ 1

t

X

8

X

7

X

6

X

5

4

X

Transmit data

X

3

Figure 47: Data Whitening

5.5.7. Interrupt Signal Mapping

Tables below give the description of the interrupts available in Packet mode.

Rev 8 – February 2013

Page 54 of 92 www.semtech.com

X

2

1

X

Whitened data

X

0

WIRELESS & SENSING

Table 23: Interrupt Mapping in Rx and Stby in Packet Mode

SX1211

Rx_stby_irq_x

00 (d) Payload_ready -

IRQ_0

IRQ_1

01 Write_byte ­10 /Fifoempty /Fifoempty
11 Sync or Adrs_match* -

00 (d) CRC_OK -

01 Fifofull Fifofull
10 RSSI ­11 Fifo_threshold Fifo_threshold

*The latter if Address filtering is enabled

IRQ_0

IRQ_1

Tx_start_irq_0=0 (d) Fifo_threshold
Tx_start_irq_0=1 /Fifoempty

Tx_irq_1=0 (d) Fifofull

Tx_irq_1=1 Tx_done

Table 24: Interrupt Mapping in Tx Packet Mode

5.5.8. uC Connections

SX1211

Rx Stby

Tx

IRQ_0

IRQ_1

NSS_CONFIG

NSS_DATA

SCK
MOSI
MISO

uC

Figure 48: uC Connections in Packet Mode

Note that depending upon the application, some uC connections may not be needed:

 IRQ_0: if none of the relevant IRQ sources are used. In this case, leave floating.
 IRQ_1: if none of the relevant IRQ sources are used. In this case, leave floating.
 MISO: if no read register access is needed and the chip is used in Tx mode only. In this case, pull up to VDD

through a 100 k resistor.

In addition, DATA pin (unused in packet mode) should be pulled-up to VDD through a 100 k resistor.
Please refer to Table 13 for the SX1211’s pin configuration.

Rev 8 – February 2013

Page 55 of 92 www.semtech.com

SX1211

(1)

(1)

WIRELESS & SENSING

5.5.9. Packet Mode Example

 Configure all data processing related registers listed below appropriately. In this example we assume CRC is

enabled with autoclear on.

Table 25: Relevant Configuration Registers in Packet Mode (data processing related only)

MCParam

IRQParam

RXParam

SYNCParam

PKTParam

fixed format only

Tx Rx

Data_mode_x X X Defines data operation mode (ÆPacket)

Fifo_size X X Defines FIFO size

Fifo_thresh X X Defines FIFO threshold
Rx_stby_irq_0 X Defines IRQ_0 source in Rx & Stby modes
Rx_stby_irq_1 X Defines IRQ_1 source in Rx & Stby modes

Tx_irq_1 X Defines IRQ_1 source in Tx mode

Tx_start_irq_0 X Defines Tx start condition and IRQ_0 source

Sync_size X X Defines Sync word size

Sync_tol X Defines the error tolerance on Sync word detection

Sync_value X X Defines Sync word value
Manchester_on X X Enables Manchester encoding/decoding
Payload_length X

Node_adrs X Defines node address for Rx address filtering
Pkt_format X X Defines packet format (fixed or variable length)

Preamble_size X Defines the size of preamble to be transmitted

Whitening_on X X Enables whitening/de-whitening process

CRC_on X X Enables CRC calculation/check

Adrs_filt X Enables and defines address filtering

CRC_autoclr X Enables FIFO autoclear if CRC failed

Fifo_stby_access X X Defines FIFO access in Stby mode

Description

X Length in fixed format, max Rx length in variable format

Tx Mode:
 Program Tx start condition and IRQs: Start Tx when FIFO not empty (Tx_start_irq_0=1) and IRQ_1 mapped to

Tx_done (Tx_irq_1=1)

 Go to Stby mode
 Write all payload bytes into FIFO (Fifo_stby_access=0, Stby interrupts can be used if needed)
 Go to Tx mode. When Tx is ready (automatically handled) Tx starts (Tx_start_irq_0=1).
 Wait for Tx_done interrupt (+1 bit period)
 Go to Sleep mode

Rx Mode:
 Program Rx/Stby interrupts: IRQ_0 mapped to /Fifoempty (Rx_stby_irq_0=10) and IRQ_1 mapped to CRC_OK

(Rx_stby_irq_1=00)

 Go to Rx (note that Rx is not ready immediately, see section 7.3.1
 Wait for CRC_OK interrupt
 Go to Stby
 Read payload bytes from FIFO until /Fifoempty goes low. (Fifo_stby_access =1)
 Go to Sleep mode

5.5.10. Additional Information

If the number of bytes filled for transmission is greater than the actual length of the packet to be transmitted and
Tx_start_irq_0 = 1, then the FIFO is cleared after the packet has been transmitted. Thus the extra bytes in the

Rev 8 – February 2013

Page 56 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

FIFO are lost. On the other hand if Tx_start_irq_0 = 0 then the extra bytes are kept into the FIFO. This opens up
the possibility of transmitting more than one packet by filling the FIFO with multiple packet messages.

It is not possible to receive multiple packets. Once a packet has been received and filled into the FIFO all its
content needs to be read i.e. the FIFO must be empty for a new packet reception to be initiated.

The Payload_ready interrupt goes high when the last payload byte is available in the FIFO and remains high until
all its data are read. Similar behavior is applicable to Adrs_match and CRC_OK interrupts.

The CRC result is available in the CRC_status bit as soon as the CRC_successful and Payload_ready interrupt
sources are triggered. In Rx mode, CRC_status is cleared when the complete payload has been read from the
FIFO. If the payload is read in Stby mode, then CRC_status is cleared when the user goes back to Rx mode and a
new Sync word is detected.

The Fifo_fill_method and Fifo_fill bits don’t have any meaning in the Packet mode and should be set to their default
values only.

Rev 8 – February 2013

Page 57 of 92 www.semtech.com

WIRELESS & SENSING

6. Configuration and Status Registers

6.1. General Description

Table 26 sums-up the control and status registers of the SX1211:

Table 26: Registers List

Name Size Address Description

MCParam 13 x 8 0 - 12 Main parameters common to transmit and receive modes
IRQParam 3 x 8 13 - 15 Interrupt registers
RXParam 6 x 8 16 - 21 Receiver parameters
SYNCParam 4 x 8 22 – 25 Pattern
TXParam 1 x 8 26 Transmitter parameters
OSCParam 1 x 8 27 Crystal oscillator parameters
PKTParam 4 x 8 28 - 31 Packet handler parameters

6.2. Main Configuration Register - MCParam

The detailed description of the MCParam register is given in Table 27.

SX1211

Table 27: MCParam Register Description

Name Bits

Chip_mode 7-5 0 r/w

Freq_band 4-3 0 r/w

VCO_trim 2-1 0 r/w

RPS_select 0 0 r/w

Modul_select 7-6 1 r/w

Data_mode_0 5 1 r/w Data operation mode LSB (refer to Data_Mode_1 (Bit 2 Addr 1)

OOK_thresh_type 4-3 1 r/w

Address
(d)

RW Description

Transceiver mode:
000 Æ sleep mode - Sleep
001 Æ stand-by mode - Stby (d)
010 Æ frequency synthesizer mode - FS
011 Æ receive mode - Rx
100 Æ transmit mode - Tx
Frequency band:
00 Æ 902 – 915 MHz
01 Æ 915 – 928 MHz (d)
10 Æ 950 – 960 MHz or 863 - 870 MHz (Application Circuit dependant)
Fine VCO trimming:
00 Æ Vtune determined by tank inductors values (d)
01 Æ Vtune + 60 mV typ.
10 Æ Vtune + 120 mV typ.
11 Æ Vtune + 180 mV typ.
Selection between the two sets of frequency dividers of the PLL, Ri/Pi/Si
0 Æ R1/P1/S1 selected(d)
1 Æ R2/P2/S2 selected
Modulation type:
01 Æ OOK
10 Æ FSK (d)

OOK demodulator threshold type:
00 Æ fixed threshold mode
01 Æ peak mode (d)
10 Æ average mode
11 Æ reserved

Rev 8 – February 2013

Page 58 of 92 www.semtech.com

WIRELESS & SENSING

Data operation mode’s MSB. Cf. Data_mode_0 (Bit 5 Addr 1)

Data_mode_1

Data_mode_1 2 1 r/w

IF_gain 1-0 1 r/w

Freq_dev 7-0 2 r/w

Res 7 3 r/w

BR

OOK_
floor_thresh

Fifo_size 7:6 5 r/w

Fifo_thresh 5-0 5 r/w

R1 7-0 6 r/w

P1 7-0 7 r/w

S1 7-0 8 r/w

R2 7-0 9 r/w

P2 7-0 10 r/w

S2 7-0 11 r/w

Res 7-5 12 r/w

PA_ramp 4-3 12 r/w

Res 2-0 12 r/w

6-0 3 r/w

7-0 4 r/w

Bit 2 addr 1

0 0 Continuous (d)
0 1 Buffered

Gain on the IF chain:
00 Æ maximal gain (0dB) (d)
01 Æ -4.5 dB
10 Æ -9dB
11 Æ -13.5 dB
Single side frequency deviation in FSK Transmit mode:
Refer to sections 3.3.4 and 3.3.5

Fdev =

(d): D = “00000011” => Fdev = 100 kHz
Reserved
(d): “0”

Bit Rate =

(d): C = “0000111” => Bit Rate = 25 kb/s NRZ
Floor threshold in OOK Rx mode. By default 6 dB.

(d): “00001100” assuming 0.5 dB RSSI step
FIFO size selection:

00 Æ 16 bytes (d)
01 Æ 32 bytes
10 Æ 48 bytes
11 Æ 64 bytes

FIFO threshold for interrupt source (Cf section 5.2.2.3)
(d): B = “001111”

R counter, active when RPS_select=”0”
(d):77h; default values of R1, P1, S1 generate 915.0 MHz in FSK mode
P counter, active when RPS_select=”0”
(d): 64h; default values of R1, P1, S1 generate 915.0 MHz in FSK mode
S counter, active when RPS_select=”0”
(d): 32h; default values of R1, P1, S1 generate 915.0 MHz in FSK mode
R counter, active when RPS_select=”1”
(d): 74h; default values of R2, P2, S2 generate 920.0 MHz in FSK mode
P counter, active when RPS_select=”1”
(d): 62h; default values of R2, P2, S2 generate 920.0 MHz in FSK mode
S counter, active when RPS_select=”1”
(d): 32h; default values of R2, P2, S2 generate 920.0 MHz in FSK mode
Reserved
(d): “001”
Ramp control of the rise and fall times of the Tx PA regulator output voltage in
OOK mode:
00 Æ 3us
01 Æ 8.5 us
10 Æ 15 us
11 Æ 23 us (d)
Reserved
(d):”000”

1 x Packet

f

XTAL

f

1) (D32 +⋅

XTAL

SX1211

Data_mode_0
Bit 5 addr 1

, 0  D  255, where D is the value in the register.

, 0  C  127, where C is the value in the register.

1) (C64 +⋅

Data Operation
Mode

Rev 8 – February 2013

Page 59 of 92 www.semtech.com

WIRELESS & SENSING

6.3. Interrupt Configuration Parameters - IRQParam

The detailed description of the IRQParam register is given in Table 28.

Table 28: IRQParam Register Description

Name Bits

Rx_stby_irq_0 7-6 13 r/w

Rx_stby_irq_1 5-4 13 r/w

Tx_irq_1 3 13 r/w

Fifofull 2 13 r

/Fifoempty 1 13 r

Fifo_overrun_clr 0 13

Fifo_fill_method 7 14 r/w FIFO filling method (Buffered mode only):

Address
(d)

RW Description

IRQ_0 source in Rx and Standby modes:

If Data_mode(1:0) = 00 (Continuous mode):
00 Æ Sync (d)
01 Æ RSSI
10 Æ Sync
11 Æ Sync
If Data_mode(1:0) = 01 (Buffered mode):
00 Æ - (d)
01 Æ Write_byte
10 Æ /Fifoempty*
11 Æ Sync
If Data_mode(1:0) = 1x (Packet mode):
00 Æ Payload_ready (d)
01 Æ Write_byte
10 Æ /Fifoempty*
11 Æ Sync or Adrs_match (the latter if address filtering is enabled)

*also available in Standby mode (Cf sections 5.4.4 and 5.5.7)
IRQ_1 source in Rx and Standby modes:

If Data_mode(1:0) = 00 (Continuous mode):
xx Æ DCLK
If Data_mode(1:0) = 01 (Buffered mode):
00 Æ - (d)
01 Æ Fifofull*
10 Æ RSSI
11 Æ Fifo_threshold*
If Data_mode(1:0) = 1x (Packet mode):
00 Æ CRC_ok (d)
01 Æ Fifofull*
10 Æ RSSI
11 Æ Fifo_threshold*

*also available in Standby mode (Cf sections 5.4.4 and 5.5.7)
IRQ_1 source in Tx mode:

If Data_mode(1:0) = 00 (Continuous mode):
x Æ DCLK
If Data_mode(1:0) = 01 (Buffered mode) or 1x (Packet mode):
0 Æ Fifofull (d)
1 Æ Tx_done
Fifofull IRQ source
Goes high when FIFO is full.
/Fifoempty IRQ source
Goes low when FIFO is empty

r/w/c Goes high when an overrun error occurred. Writing a 1 clears flag and FIFO

SX1211

Rev 8 – February 2013

Page 60 of 92 www.semtech.com

WIRELESS & SENSING

0 Æ Automatically starts when a sync word is detected (d)
1 Æ Manually controlled by Fifo_fill
FIFO filling status/control (Buffered mode only):

 If Fifo_fill_method = ‘0’: (d)

Goes high when FIFO is being filled (sync word has been detected)

Fifo_fill 6 14

Tx_done 5 14 r

r/w/

Writing ‘1’ clears the bit and waits for a new sync word (if Fifo_overrun_clr=0)

c

 If Fifo_fill_method = ‘1’:

0 Æ Stop filling the FIFO
1 Æ Start filling the FIFO
Tx_done IRQ source
Goes high when the last bit has left the shift register.
Tx start condition and IRQ_0 source:

 If Data_mode(1:0) = 01 (Buffered mode):

0 Æ Tx starts if FIFO is full, IRQ_0 mapped to /Fifoempty (d)
1 Æ Tx starts if FIFO is not empty, IRQ_0 mapped to /Fifoempty

Tx_start_irq_0 4 14 r/w

Res 3 14 r/w

RSSI_irq 2 14

PLL_locked 1 14

PLL_lock_en 0 14 r/w

RSSI_irq_thresh 7-0 15

 If Data_mode(1:0) = 1x (Packet mode):

0 Æ Start transmission when the number of bytes in FIFO is greater than or
equal to the threshold set by MCParam_Fifo_thresh parameter (Cf section

5.2.2.3), IRQ_0 mapped to Fifo_threshold (d)
1 Æ Tx starts if FIFO is not empty, IRQ_0 mapped to /Fifoempty
(d): “0”, should be set to “1”.
Note: “0” disables the RSSI IRQ source. It can be left enabled at any time, and
the user can choose to map this interrupt to IRQ0/IRQ1 or not.
RSSI IRQ source:

r/w/

Goes high when a signal above RSSI_irq_thresh is detected

c

Writing ‘1’ clears the bit
PLL status:

r/w/

0 Æ not locked

c

1 Æ locked
Writing a ‘1’ clears the bit
PLL_lock detect flag mapped to pin 23:
0 Æ Lock detect disabled, pin 23 is High-Z
1 Æ Lock detect enabled(d)
RSSI threshold for interrupt (coded as RSSI)
(d): “00000000”

SX1211

Rev 8 – February 2013

Page 61 of 92 www.semtech.com

+

M

+

WIRELESS & SENSING

6.4. Receiver Configuration parameters - RXParam

The detailed description of the RXParam register is given in Table 29.

Table 29: RXParam Register Description

Name Bits Address (d) RW Description

Typical single sideband bandwidth of the passive low-pass filter.
PassiveFilt = 0000 Æ 65 kHz
0001 Æ 82 kHz
0010 Æ 109 kHz
0011 Æ 137 kHz
0100 Æ 157 kHz
0101 Æ 184 kHz
0110 Æ 211 kHz

PassiveFilt 7-4 16 r/w

ButterFilt 3-0 16 r/w

PolypFilt_center 7-4 17 r/w

Res 3-0 17 r/w

PolypFilt_on 7 18 r/w

Bitsync_off 6 18 r/w

Sync_on 5 18 r/w

Sync_size 4-3 18 r/w

Sync_tol 2-1 18 r/w

Res 0 18 r/w

0111 Æ 234 kHz
1000 Æ 262 kHz
1001 Æ 321 kHz
1010 Æ 378 kHz (d)
1011 Æ 414 kHz
1100 Æ 458 kHz
1101 Æ 514 kHz
1110 Æ 676 kHz
1111 Æ 987 kHz

Sets the receiver bandwidth. For BW information please refer to
sections 3.4.5 (FSK) and 3.4.6 (OOK).

MHzf

xtal

+=

c

0

(d): “0011” => fC –f0 = 100 kHz
Central frequency of the polyphase filter (100kHz recommended):

kHzf

=

0

(d):“0011” => f0 = 100 kHz
Reserved
(d): “1000”
Enable of the polyphase filter, in OOK Rx mode:
0 Æ off (d)
1 Æ on
Bit synchronizer: control in Continuous Rx mode:
0 Æ on (d)
1 Æ off
Sync word recognition:
0 Æ off (d)
1 Æ on
Sync word size:
00 Æ 8 bits
01 Æ 16 bits
10 Æ 24 bits
11 Æ 32 bits (d)
Number of errors tolerated in the Sync word recognition:
00 Æ 0 error (d)
01 Æ 1 error
10 Æ 2 errors
11 Æ 3 errors
Reserved
(d):”0”

.200

kHzff

8.12

MHzF

xtal

.200

.

8.12

Hz

MHz

SX1211

.

ButterFiltVal

8

centerPolypFiltVal

8

)(1

)_(1

Rev 8 – February 2013

Page 62 of 92 www.semtech.com

t

d

d

WIRELESS & SENSING

Name Bits Address (d) RW Description

Res 7-0 19 r/w

RSSI_val 7-0 20 r

Reserved
(d): “00000111”
RSSI output, 0.5 dB / bit
Note: READ-ONLY (not to be written)
Size of each decrement of the RSSI threshold in the OOK demodulator
000 Æ 0.5 dB (d) 100 Æ 3.0 dB

OOK_thresh_step 7-5 21 r/w

001 Æ 1.0 dB 101 Æ 4.0 dB
010 Æ 1.5 dB 110 Æ 5.0 dB
011 Æ 2.0 dB 111 Æ 6.0 dB
Period of decrement of the RSSI threshold in the OOK demodulator:
000 Æ once in each chip period (d)
001 Æ once in 2 chip periods

OOK_thresh_dec
_period

4-2 21 r/w

010 Æ once in 4 chip periods
011 Æ once in 8 chip periods
100 Æ twice in each chip period
101 Æ 4 times in each chip period
110 Æ 8 times in each chip period
111 Æ 16 times in each chip period
Cutoff frequency of the averaging for the average mode of the OOK

threshold in demodulator
OOK_avg_thresh
_cutoff

1-0 21 r/w

00 Æ fC  BR / 8. (d)

01 Æ Reserved

10 Æ Reserved

11 Æ f

 BR / 32.

C

SX1211

6.5. Sync Word Parameters - SYNCParam

The detailed description of the SYNCParam register is given in Table 30.

Table 30: SYNCParam Register Description

Name Bits Address (d) RW Description

Sync_value(31:24) 7-0 22 r/w 1

Sync_value(23:16) 7-0 23 2

Sync_value(15:8) 7-0 24 3

Sync_value(7:0) 7-0 25 4th Byte of Sync word (only used if Sync_size = 11)

s

Byte of Sync word

(d): “00000000”

n

Byte of Sync word (only used if Sync_size  00)

(d): “00000000”

r

Byte of Sync word (only used if Sync_size = 1x)

(d): “00000000”

(d): “00000000”

Rev 8 – February 2013

Page 63 of 92 www.semtech.com

+

=

WIRELESS & SENSING

6.6. Transmitter Parameters - TXParam

The detailed description of the TXParam register is given in Table 31.

Table 31: TXParam Register Description

Name Bits Address (d) RW Description

InterpFilt 7-4 26 r/w Tx Interpolation filter cut off frequency:

MHzF

kHzfc

xtal

.200

8.12

MHz

= 200 kHz

C

.

8

=

(d): “0111” => f

Pout 3-1 26 r/w Tx output power (1 step  3 dB):

000 Æ 13 dBm
001 Æ 13 dBm -1 step (d)
010 Æ 13 dBm – 2 steps
011 Æ 13 dBm – 3 steps
100 Æ 13 dBm – 4 steps
101 Æ 13 dBm – 5 steps
110 Æ 13 dBm – 6 steps
111 Æ 13 dBm – 7 steps

Res 0 26 r/w Reserved

(d): “0”

SX1211

)(1

TxInterpFiltVal

6.7. Oscillator Parameters - OSCParam

The detailed description of the OSCParam register is given in Table 32.

Table 32: OSCParam Register Description

Name Bits Address

(d)

Clkout_on 7 27 r/w Clkout control

Clkout_freq 6-2 27 r/w Frequency of the signal provided on CLKOUT:

Res 1-0 27 r/w Reserved

RW Description

0 Æ Disabled
1 Æ Enabled, Clk frequency set by Clkout_freq (d)

if Clkout_freq = “00000”

ffclkout

xtal

f

fclkout

(d): 01111 (= 427 kHz)

(d): “00”

=

xtal

_2⋅

otherwise

freqClkout

Rev 8 – February 2013

Page 64 of 92 www.semtech.com

WIRELESS & SENSING

6.8. Packet Handling Parameters – PKTParam

The detailed description of the PKTParam register is given in Table 33.

Table 33: PKTParam Register Description

Name Bits Address

(d)

Manchester_on 7 28 r/w Enable Manchester encoding/decoding:

Payload_length 6-0 28 r/w If Pkt_format=0, payload length.

Node_adrs 7-0 29 r/w Node’s local address for filtering of received packets.

Pkt_format 7 30 r/w Packet format:

Preamble_size 6-5 30 r/w Size of the preamble to be transmitted:

Whitening_on 4 30 r/w Whitening/dewhitening process:

CRC_on 3 30 r/w CRC calculation/check:

Adrs_filt 2-1 30 r/w Address filtering of received packets:

CRC_status 0 30 r CRC check result for current packet (READ ONLY):

CRC_autoclr 7 31 r/w FIFO auto clear if CRC failed for current packet:

Fifo_stby_access 6 31 r/w FIFO access in standby mode:

Res 5-0 31 r/w Reserved

RW Description

0 Æ off (d)
1 Æ on

If Pkt_format=1, max length in Rx, not used in Tx.
(d): “0000000”

(d): 00h

0 Æ fixed length (d)
1 Æ variable length

00 Æ 1 byte
01 Æ 2 bytes
10 Æ 3 bytes (d)
11 Æ 4 bytes

0 Æ off (d)
1 Æ on

0 Æ off
1 Æ on (d)

00 Æ off (d)
01 Æ Node_adrs accepted, else rejected.
10 Æ Node_adrs & 0x00 accepted, else rejected.
11 Æ Node_adrs & 0x00 & 0xFF accepted, else rejected.

0 Æ Fail
1 Æ Pass

0Æ on (d)
1Æ off

0Æ Write (d)
1Æ Read

(d): “000000”

SX1211

Rev 8 – February 2013

Page 65 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7. Application Information

7.1. Crystal Resonator Specification

Table 34 shows the crystal resonator specification for the crystal reference oscillator circuit of the SX1211. This
specification covers the full range of operation of the SX1211 and is employed in the reference design (see section

7.5.3).

Table 34: Crystal Resonator Specification

Name Description Min. Typ. Max. Unit

Fxtal Nominal frequency 9 12.800 15 MHz
Cload Load capacitance for Fxtal 10 15 16.5 pF
Rm Motional resistance - - 100 ohms
Co Shunt capacitance 1 - 7 pF

ΔFxtal
ΔFxtal(ΔT)

ΔFxtal(Δt)

Note that 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.

Calibration tolerance at 25+/-3°C -15 - +15 ppm
Stability over temperature range [-40°C ; +85°C] -20 - +20 ppm

Ageing tolerance in first 5 years -2 - +2 ppm/year

7.2. Software for Frequency Calculation

The R1, P1, S1, and R2, P2, S2 dividers are configured over the SPI interface and programmed by 8 bits each, at
addresses 6 to 11. The frequency pairs may hence be switched in a single SPI cycle.

7.2.1. GUI

To aid the user with calculating appropriate R, P and S values, software is available to perform the frequency
calculation. The SX1211 PLL frequency Calculator Software can be downloaded from the Semtech website.

7.2.2. .dll for Automatic Production Bench

The Dynamically Linked Library (DLL) used by the software to perform these calculations is also provided, free of
charge, to users, for inclusion in automatic production testing. Key benefits of this are:
 No hand trimming of the reference frequency required: the actual reference frequency of the Device Under Test

(DUT) can be easily measured (e.g. from the CLKOUT output of the SX1211) and the tool will calculate the
best frequencies to compensate for the crystal initial error.

 Channel plans can be calculated and stored in the application’s memory, then adapted to the actual crystal

oscillator frequency.

7.3. Switching Times and Procedures

As an ultra-low power device, the SX1211 can be configured for low minimum average power consumption. To
minimize consumption the following optimized transitions between modes are shown.

Rev 8 – February 2013

Page 66 of 92 www.semtech.com

WIRELESS & SENSING

7.3.1. Optimized Receive Cycle

The lowest-power Rx cycle is the following:

SX1211

IDD

IDDR

3.0mA typ.

IDDFS

1.3mA typ.

IDDST

65uA typ.

IDDSL

100nA typ.

SX1211

Time

Wait

TS RE

Rx

time

SX1211 can be put in
Any other mode

Receiver is ready :

-RSSI sampling is valid after a 1/Fdev period

-Received data is valid

Wait

TS FS

Wait

TS OSC

Set SX1211 in Standby mode
Wait for XO settling

Set SX1211 in FS mode
Wait for PLL settling

Set SX1211 in Rx mode
Wait for Receiver settling

Figure 49: Optimized Rx Cycle

Note: If the lock detect indicator is available on an external interrupt pin of the companion uC, it can be used to
optimize TS_FS, without having to wait the maximum specified TS_FS.

Rev 8 – February 2013

Page 67 of 92 www.semtech.com

WIRELESS & SENSING

7.3.2. Optimized Transmit Cycle

SX1211

IDD

SX1211

16mA typ. @1dBm

IDDT

IDDFS

1.3mA typ.

IDDST

65uA typ.

IDDSL

100nA typ.

Wait

TS OSC

Wait

TS TR

Wait

TS FS

Set SX1211 in FS mode
Wait for PLL settling

Tx

time

Data transmission can start in
Continuous and Buffered
modes

Set SX1211 in Tx mode
Packet mode starts its operation

SX1211 can be put in
Any other mode

Time

Set SX1211 in Standby mode
Wait for XO settling

Figure 50: Optimized Tx Cycle

Note: As stated in the preceding section, TS_FS time can be improved by using the external lock detector pin as
external interrupt trigger.

Rev 8 – February 2013

Page 68 of 92 www.semtech.com

WIRELESS & SENSING

7.3.3. Transmitter Frequency Hop Optimized Cycle

SX1211

IDD

16mA typ. @1dBm

IDDT

IDDFS

1.3mA typ.

SX1211

SX1211 is in Tx mode
On channel 1 (R1/P1/S1)

Wait

TS TR

Wait

TS HOP

1. Set R2/P2/S2

2. Set SX1211 in FS mode, change

MCParam_Band if needed, then switch
from R1/P1/S1 to R2/P2/S2

Figure 51: Tx Hop Cycle

SX1211 is now ready
for data transmission

Set SX1211 back in Tx mode

Time

Rev 8 – February 2013

Page 69 of 92 www.semtech.com

WIRELESS & SENSING

7.3.4. Receiver Frequency Hop Optimized Cycle

SX1211

IDD

IDDR

3mA typ

IDDFS

1.3mA typ.

SX1211

Time

SX1211 is in Rx mode
On channel 1 (R1/P1/S1)

Wait

TS HOP

Wait

TS RE

1. Set R2/P2/S2

2. Set SX1211 in FS mode, change

MCParam_Band if needed, then switch
from R1/P1/S1 to R2/P2/S2

SX1211 is now ready
for data reception

Set SX1211 back in Rx mode

Figure 52: Rx Hop Cycle

Note: it is also possible to move from one channel to the other one without having to switch off the receiver. This
method is faster, and overall draws more current. For timing information, please refer to TS_RE_HOP on Table 8.

Rev 8 – February 2013

Page 70 of 92 www.semtech.com

WIRELESS & SENSING

7.3.5. RxÆTx and TxÆRx Jump Cycles

SX1211

IDD

16mA typ. @1dBm

IDDT

IDDR

3.0mA typ.

SX1211

SX1211 is in
Rx mode

Wait

TS TR

Set SX1211 in
Tx mode

Figure 53: Rx

Wait

TS RE

SX1211 is now ready
for data transmission

Æ

Tx Æ Rx Cycle

Set SX1211 in
Rx mode

Time

SX1211 is ready to
receive data

Rev 8 – February 2013

Page 71 of 92 www.semtech.com

SX1211

(input)

WIRELESS & SENSING

7.4. Reset of the Chip

A power-on reset of the SX1211 is triggered at power up. Additionally, a manual reset can be issued by controlling
pin 13.

7.4.1. POR

If the application requires the disconnection of VDD from the SX1211, 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 13 (TEST8) should be left floating during the POR sequence.

VDD

Pin 13
(output)

Please note that any CLKOUT activity can also be used to detect that the chip is ready.

Undefined

Wait for

10 ms

Figure 54: POR Timing Diagram

Chip is ready from
this point on

7.4.2. Manual Reset

A manual reset of the SX1211 is possible even for applications in which VDD cannot be physically disconnected.
Pin 13 should be pulled high for a hundred microseconds, and then released. The user should then wait for 5 ms
before using the chip.

VDD

> 100 us

Pin 13

Figure 55: Manual Reset Timing Diagram

Please note that while pin 13 is driven high, an over current consumption of up to ten milliamps can be seen on
VDD.

High-Z

Wait for

5 ms

High-Z’’1’’

Chip is ready from
this point on

Rev 8 – February 2013

Page 72 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7.5. Reference Design

It is recommended that this reference design (i.e. schematics, placement, layout, BOM,) is replicated in the final
application board to guarantee optimum performance.

7.5.1. Application Schematic

Figure 56: Reference Design Circuit Schematic

The reference design area is represented by the dashed rectangle. C12 is a DC blocking capacitor which protects
the SAW filter. It has been added for debug purposes could be removed for a direct antenna connection if there is
no DC bias is expected at the antenna port. Please note that C10 and C11 are not used.

7.5.2. PCB Layout

As illustrated in figures below, the layout has the following characteristics:

 very compact (9x19mm) => can be easily inserted even on very small PCBs
 standard PCB technology (2 layers, 1.6mm, std via & clearance) => low cost
 Its performance is quasi-insensitive to dielectric thickness => minimal design effort to transfer to other PCB

technologies (thickness, # of layers, etc...)

Rev 8 – February 2013

Page 73 of 92 www.semtech.com

WIRELESS & SENSING

The layers description is illustrated in Figure 57:

SX1211

Signal (35um)

Isolation (FR4, 1.6mm)

Ground plane

Figure 57: Reference Design‘s Stackup

The layout itself is illustrated in Figure 58. Please contact Semtech for gerber files.

19mm

9mm

Figure 58: Reference Design Layout (top view)

7.5.3. Bill Of Material

Table 35: Reference Design BOM

Value Ref

868MHz 915MHz

U1 SX1211 - Transceiver IC TQFN-32 ­U2 869 MHz 915 MHz - SAW Filter 3.8*3.8 mm Plotted in section 7.5.4
Q1 12.8 MHz 15 ppm at 25°C

R1 1 1% - 0402 PA regulator
R2 6.8 k 1% - 0402 Loop filter
C1 1uF 15% X5R 0402 VDD decoupling
C2 1uF 15% X5R 0402 Top regulator decoupling
C3 220 nF 10% X7R 0402 Digital regulator decoupling
C4 47 nF 10% X7R 0402 PA regulator decoupling
C5 100 nF 10% X7R 0402 VCO regulator decoupling
C6 10 nF 10% X7R 0402 Loop Filter
C7 680 pF 5% NPO 0402 Loop Filter
C8 1.8 pF 0.25 pF NPO 0402 Matching
C9 22 pF 5% NPO 0402 DC block and L4 adjust

L1, L2 8.2 nH 6.8 nH 0.2 nH Wire wound 0402 VCO tank inductors

L3 100 nH 5% Wire wound 0402 PA Choke
L4 8.2 nH 5% Multilayer 0402 Matching

C10, C11 NC - - 0402 -

C12* 47pF 5% NPO 0402 DC block

*Not part of the ref. design (not required for direct antenna connection).

Tol (+/-) Techno Size Comment

AT-cut 5.0*3.2 mm Fundamental, Cload=15 pF
20 ppm over -40/+85°C
2ppm/year max

Note: for battery powered applications, a high value capacitance should be implemented in parallel with C1
(typically 10 µF) to offer a low impedance voltage source during startup sequences.

Rev 8 – February 2013

Page 74 of 92 www.semtech.com

WIRELESS & SENSING

7.5.4. SAW Filter Plot

The following screenshot shows the plot of the SAW filter used on the reference design:

0

-10

-20

-30

-40

Attenuati o n [dB]

-50

-60

-70

-80
400 600 800 1000 1200 1400 1600 1800 2 000

Figure 59: 915 MHz SAW Filter Plot

Frequency [MHz]

SX1211

0

-10

-20

-30

-40

Attenuation [dB]

-50

-60

-70

-80
400 600 800 1000 1200 1400 1600 1800 2000

Freque ncy [MHz]

Figure 60: 869 MHz SAW Filter Plot

7.5.5. Ordering Information for Tools

The modules described in section 7.5 can be ordered through your Semtech representative for evaluation purpose:

Table 36: Tools Ordering Information

Part Number Description

SM1211E868 2 layer RF module, 868 MHz band
SM1211E915 2 layer RF module, 915 MHz band
SX1211-11SKA868 Full evaluation kit with 2 RF and controller boards, antennas and cables
SX1211-11SKA915 Full evaluation kit with 2 RF and controller boards, antennas and cables

Rev 8 – February 2013

Page 75 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7.6. Reference Design Performance

All the measurements visible on section 7.6 typical figures obtained under the following conditions, unless
otherwise noted:

 Nominal VDD = 3.3 V
 Tests performed at room temperature: 25°C +/-3°C
 Center frequency 869 MHz or 915 MHz
 {R, P, S} triplets are those calculated by the software described in section 3.2.8.
 All register settings are default, except for those stated in the relevant sub-sections
 Maximum Output Power programmed on Pout tests
 All sensitivities are evaluated in Continuous mode, demodulating a PN15 sequence, BER=0.1%
 FSK sensitivities measured at 25kbps, Fdev=+/-50 kHz
 OOK sensitivities measured at 8kbps, with Fo=100 kHz. IF2 set to 100 kHz.
 On all Adjacent Channel Rejection (ACR), Blocking and Spurious Response Frequency tests, the unwanted

signal is unmodulated.

 Bill of Materials as shown in section 7.5.3. In particular, a SAW filter is used (see its performance on section

7.5.4)

 The filter settings described on Table 37 and Table 38 were used for the measurements of section 7.6.5.

Table 37: FSK Rx Filters vs. Bit Rate

Setting

Addr 16

kbps +/- kHz Hex kHz kHz kHz +/- ppm

100 200 FF 250 400 306 62

66.67 133 E9 166.7 250 214 53
50 100 D6 125 175 158 37
40 80 B5 100 150 137 41

33.33 67 A4 83.3 125 116 36

28.57 57 A3 71.4 100 96 27
25 50 A3 62.5 100 96 37

22.22 44 72 55.6 75 69 15
20 40 72 50 75 69 21

18.18 36 72 45.5 75 69 26

16.67 33 72 41.7 75 69 30

15.38 33 41 41 50 47 7

14.29 33 41 40.5 50 47 7

12.5 33 41 39.6 50 47 8
10 33 41 38.3 50 47 10

5 33 41 35.8 50 47 12
2 33 41 34.3 50 47 14

Fdev

+

BR/2

Rx 3 dB BW Bit Rate Fdev Filter

Programmed Actual

Max. drift

Table 38: OOK Rx Filters vs. Bit Rate

Setting

Addr 16

kbps kHz Hex kHz kHz +/- ppm

16.67

12.5

9.52

8

4.76

2.41

1.56

117 C1 150 154 41
113 C1 150 154 46
110 A0 125 129 22
108 A0 125 129 23
105 A0 125 129 27
102 A0 125 129 30
102 A0 125 129 30

Rx 3 dB BW Bit Rate FO + BR Filter

Programmed Actual

Max.

drift

Rev 8 – February 2013

Page 76 of 92 www.semtech.com

WIRELESS & SENSING

7.6.1. Sensitivity Flatness

SX1211

Sensitivi ty over t he Frequency Band

-90.0

-92.0

-94.0

-96.0

-98.0

-100.0

Sensitivity @ BER=0.1%

-102.0

-104.0

-106.0
863 864 865 866 867 868 869 870

Frequency [MHz]

Sensitivity SAW Ripple

Figure 61: Sensitivity Across the 868 MHz Band

Sensitivi t y over t he Frequency Band

-90.0

-92.0

-94.0

-96.0

-98.0

-100.0

Sensitivity [dBm]

-102.0

-104.0

-106.0
902 904 906 908 910 912 914 916 918 9 20 922 924 926 928

Frequency [MHz]

Sensitivit y SAW Ripple

Figure 62: Sensitivity Across the 915 MHz Band

14.0

12.0

10.0

8.0

6.0

4.0

2.0

0.0

-2.0

14.0

12.0

10.0

8.0

6.0

4.0

2.0

0.0

-2.0

SAW Rip p l e [dB]

SAW Ripple [dB]

Notes:

 Measured in FSK mode only. OOK sensitivity characteristics will be similar.
 The sensitivity difference along the band remains inside the ripple performance of the SAW filter (the nominal

passband of the 869 MHz SAW filter is 868 – 870 MHz)

 The SAW filter ripple response is referenced to its insertion loss at 869 MHz and 915 MHz for each filter.

Rev 8 – February 2013

Page 77 of 92 www.semtech.com

WIRELESS & SENSING

7.6.2. Sensitivity vs. LO Drift

SX1211

Sensiti v i t y Loss vs . LO Drift

6.0

5.0

4.0

3.0

2.0

Sensitivity Lo ss [dB]

1.0

0.0

-25 -20 -15 -10 -5 0 5 10 15 20 25

-1.0

LO Drift [kHz]

Figure 63: FSK Sensitivity Loss vs. LO Drift

Sensitivit y Loss vs. LO Dri f t

6.0

5.0

4.0

3.0

2.0

Sensitivity Loss [d B]

-100 -80 -60 -40 -20 0 20 40 60 80 100

1.0

0.0

-1.0

LO Drift [kHz]

Figure 64: OOK Sensitivity Loss vs. LO Drift

Notes:

 In FSK Mode, the default filter setting (“A3” at address $16) is kept, leading to Fc=96 kHz typ.
 In OOK Mode, “F3” is set at address $16, leading to (Fc-Fo)=95 kHz typ.
 The above ensures that the channel filter is wide enough, therefore characterizing the demodulator response,

and NOT the filter response.

Rev 8 – February 2013

Page 78 of 92 www.semtech.com

WIRELESS & SENSING

7.6.3. Sensitivity vs. Receiver BW

Sensitivi ty vs. Fc

1.0

0.0
50 100 150 200 250 300

-1.0

-2.0

-3.0

-4.0

Sensitivity Improvement [dB] =>

-5.0

SX1211

-6.0

Fc of Active Filte r [kHz]

Figure 65: FSK Sensitivity vs. Rx BW

Sensitivity Change vs. (Fc-Fo)

1.0

0.0

0 50 100 150 200 250 300 350

-1.0

-2.0

-3.0

-4.0

Sensitivity I mprovem en t [dB] =>

-5.0

-6.0

Fc-Fo [kHz]

Figure 66: OOK Sensitivity Change vs. Rx BW

Rev 8 – February 2013

Page 79 of 92 www.semtech.com

WIRELESS & SENSING

>

7.6.4. Sensitivity Stability over Temperature and Voltage

Sensitivity Stability

1.5

1.0

0.5

0.0

2.10 2.40 2.70 3.00 3.30 3.60

-0.5

-1.0

Sensitivity Improvement [dB] =

-1.5

-2.0

SX1211

85°C

25°C

0°C

-40°C

-2.5

VDD [V]

Figure 67: Sensitivity Stability

Note:
 The sensitivity performance is very stable over the VDD range, and the effect of high temperature is minimal.

7.6.5. Sensitivity vs. Bit Rate

8.0

6.0

4.0

2.0

0.0
0255075100

-2.0

-4.0

Sensitivity Improvement [dB] =>

-6.0

-8.0

Figure 68: FSK Sensitivity vs. BR

Sensitivity Change over BR

Bit Rate [kb/s]

Rev 8 – February 2013

Page 80 of 92 www.semtech.com

WIRELESS & SENSING

Sensitivity Change over the BR

2.0

1.5

1.0

0.5

0.0

1.5 4 6.5 9 11. 5 14 16.5

-0.5

-1.0

Sensitivity I m p ro vement [dB] =>

-1.5

-2.0

-2.5

Bit Rate [kbps]

Figure 69: OOK Sensitivity vs. BR

SX1211

7.6.6. Adjacent Channel Rejection

ACR in FSK Mode

ACR [dB]

-1000 -800 -600 -400 -200 0 200 400 600 800 100 0

Figure 70: ACR in FSK Mode

70

60

50

40

30

20

10

0

Offset [kHz]

Rev 8 – February 2013

Page 81 of 92 www.semtech.com

WIRELESS & SENSING

SX1211

ACR in OOK M od e

60

50

40

30

20

ACR [dB]

10

-300 -200 -100 0 100 200 300

0

-10

-20

Offset [kHz]

Figure 71: ACR in OOK Mode

Notes:
 In FSK mode, the unwanted signal is unmodulated (as described in the EN 300-220 V2.1.1).Co-Channel

Rejection (CCR, Offset = 0kHz) is positive due to the DC cancellation process of the zero-IF architecture

 In OOK mode, the polyphase filter efficiency is limited, thus limiting the adjacent channel rejection at 2xFo

distance.

7.6.7. Output Power Flatness

Pout Over t he Fr equenc y Band

12.0

10.0

8.0

6.0

Pout [dBm]

4.0

4.0

2.0

0.0

-2.0

-4.0

SAW Ripple [dB]

Rev 8 – February 2013

2.0

0.0
863 864 865 866 867 868 869 870

Freque ncy [MHz]

Pout SAW Ripple

Figure 72: Pout for 869 MHz Band Operation

Page 82 of 92 www.semtech.com

-6.0

-8.0

WIRELESS & SENSING

SX1211

Pout over the Fr e quency Band

12.00

10.00

8.00

6.00

Pout [dBm]

4.00

2.00

0.00

902 904 906 908 910 912 914 916 918 920 922 924 926 928

Frequency [MHz]

Pout SAW Ripple

4.0

2.0

0.0

-2.0

-4.0

-6.0

-8.0

SAW Ripple [dB]

Figure 73: Pout for 915 MHz Band Operation

Notes:
 As noted in section 7.5.4, the 869 MHz SAW filter does not cover the whole European 863 – 870 MHz

frequency band when used in a 50 ohms environment. Hence the output power degradation at the lowest
frequencies. For applications in the 863 – 870 MHz band it is recommended that an appropriate SAW filter be
implemented or that the SAW response tuned by external matching.

 The SAW filter ripple references are the insertion loss of each SAW at 869 MHz and 915 MHz.

7.6.8. Pout and IDD vs. PA Setting

Pout & IDD vs. TXPar a m_Pout Set ting

12.0

8.0

4.0

0.0

Pout [dBm]

-4.0

-8.0

-12.0
01234567

TXParam _Pout [d]

Pout IDD

Figure 74: Pout and IDD at all PA Settings, 869 MHz

28.00

26.00

24.00

22.00

20.00

18.00

16.00

14.00

12.00

10.00

Rev 8 – February 2013

Page 83 of 92 www.semtech.com

WIRELESS & SENSING

SX1211

Pout & I DD v s . TXParam_Pout Setti ng

12.0

10.0

8.0

6.0

4.0

2.0

0.0

-2.0

Pout [dBm]

-4.0

-6.0

-8.0

-10.0

-12.0
01234567

TXParam_Pout [d]

Pout IDD

Figure 75: Pout and IDD at all PA Settings, 915 MHz

Note:
 +10dBm typ. Output power is achievable, even at SAW filter’s output.

7.6.9. Pout Stability over Temperature and Voltage

Pout Stability

1.0

30.0

28.0

26.0

24.0

22.0

20.0

18.0

16.0

14.0

12.0

10.0

IDD [m A]

0.5

0.0

2.1 2.4 2.7 3.0 3.3 3.6

-0.5

-1.0

Pout Improvement [dB] =>

-1.5

-2.0

VDD [V]

85°C

25°C

-40°C

0°C

Figure 76: Pout Stability

The output power is not sensitive to the supply voltage, and it decreases slightly when temperature rises.

Rev 8 – February 2013

Page 84 of 92 www.semtech.com

WIRELESS & SENSING

7.6.10. Transmitter Spectral Purity

SX1211

Figure 77: 869 MHz Spectral Purity DC-1GHz

Rev 8 – February 2013

Figure 78: 869 MHz Spectral Purity 1-6GHz

Page 85 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7.6.11. OOK Channel Bandwidth

The OOK bit rate ranges form 1.56 to 16.7 kbps. It is interesting to note that, for the lowest bit rates, a channel
spacing approaching 200 kHz is achievable:

Figure 79: OOK Spectrum - 2kbps

Figure 80: OOK Spectrum - 8kbps

Figure 81: OOK Spectrum - 16.7kbps

Notes:
 The test conditions are: Fdev=100 kHz, TXParam_InterpFilt = 200 kHz

Rev 8 – February 2013

Page 86 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7.6.12. FSK Spectrum in Europe

Figure 82 shows the minimal spectral occupation achievable in the European band, keeping in mind that the
minimum frequency deviation that a SX1211 receiver can accept is 33 kHz. If the companion receiver can bear
smaller frequency deviations, the range of modulation bandwidth can be further decreased.

Figure 82: FSK - 1.56kbps - +/-33 kHz

The default configuration of the SX1211 yields the bandwidth visible on Figure 83:

Figure 83: FSK - 25 kbps - +/-50 kHz

Figure 84 shows the maximal bit rate and frequency deviation that can fit in the 868 to 868.6 MHz European sub­band:

Figure 84: FSK - 40 kbps - +/-40 kHz

Rev 8 – February 2013

Page 87 of 92 www.semtech.com

SX1211

WIRELESS & SENSING

7.6.13. Digital Modulation Schemes

FCC Part 15.247 allows for systems employing digital modulation techniques to transmit up to 1 W, provided that
the 6 dB bandwidth of the signal is at least 500 kHz and that the power spectral density does not exceed 8dBm in
any 3 kHz bandwidth.

The SX1211 can actually meet these constraints whilst transmitting at the maximum output power of the device of
typ. 10dBm, thanks to the built-in whitening process described in section 5.5.6.2:

Figure 85: DTS 6dB Bandwidth

Figure 86: DTS Power Spectral Density

Conditions:

 Pout = +10.6dBm
 Fdev = +/-200kHz
 BR=100 kbps (Chip rate=100kCps, as data whitening is enabled)
 Packet mode, data whitening enabled

Note: Manchester encoding allows meeting an even lower power spectral density, at the expense of the bit rate
efficiency.

Rev 8 – February 2013

Page 88 of 92 www.semtech.com

WIRELESS & SENSING

7.6.14. Current Stability over Temperature and Voltage

SX1211

1200

1000

800

600

Isleep [nA]

400

200

0

2.1 2.4 2.7 3 3. 3 3.6

2.00

1.80

1.60

1.40

1.20

1.00

Ifs [mA]

0.80

0.60

0.40

0.20

0.00

2.1 2.4 2.7 3 3.3 3.6

Sleep Mode Current

VDD [V]

FS Mode Current

VDD [V]

85°C

25°C

0°C

-40°C

85°C

25°C

0°C

-40°C

100

90

80

70

60

50

Istby [uA]

40

30

20

10

0

2.1 2.4 2.7 3 3.3 3. 6

4.00

3.50

3.00

2.50

2.00

Irx [mA]

1.50

1.00

0.50

0.00

2.1 2.4 2.7 3 3.3 3.6

Standby Mode Current

VDD [V]

Rx Mode Current

VDD [V]

85°C

25°C

0°C

-40°C

85°C

25°C

0°C

-40°C

Rev 8 – February 2013

Tx Mode Current

30.0

25.0

20.0

15.0

Itx [mA ]

TXLVL=000

10.0

5.0

0.0

2.1 2. 4 2.7 3. 0 3.3 3. 6

(Max Output Power)

VDD [V]

Figure 87: IDD vs. Temp and VDD

Page 89 of 92 www.semtech.com

85°C

25°C

-40°C

0°C

WIRELESS & SENSING

8. Packaging Information

8.1. Package Outline Drawing

SX1211 is available in a 32-lead TQFN package as shown in Figure 88 below.

SX1211

8.2. PCB Land Pattern

Rev 8 – February 2013

Figure 88: Package Outline Drawing

Figure 89: PCB Land Pattern

Page 90 of 92 www.semtech.com

WIRELESS & SENSING

g

8.3. Tape & Reel Specification

SX1211

Direction of Feed

Tape

Width(W)

+/-0.3

Notes:
*all dimensions in mm

*sin

Carrier Tape Reel

Pocket

Pitch (P)

12

+/-0.1

le sprocket holes

Ao/Bo Ko

8

5.25

+/-0.2

1.10

+/-0.1

Reel
Size

330.2 12.4 400 400 3000

Reel

Width

Min.Trail

er Length

Min.
Leader
Length

QTY per

Reel

Figure 90: Tape & Reel Dimensions

Rev 8 – February 2013

Page 91 of 92 www.semtech.com

WIRELESS & SENSING

9. Revision History

SX1211

Revision 5

 Increase maximum Bit Rate in FSK
 Update minimum XO frequency
 Add the manual reset description
 Insert decoupling recommendation for battery

operated systems

 Add Tools ordering information

Revision 6

 Update SPI speed
 Clarify default fc value in Table 29
 Clarify MISO state in SPI timing figures
 Improve ESD rating description

10. Contact Information

Semtech Corporation

Wireless and Sensing Products Division

200 Flynn Road, Camarillo, CA 93012

Revision 7

 Describe PLL_LOCK pin state in Table 13
 Improve note in section 5.4.1
 Clarify Table 5 measurement conditions
 Clarify /Fifoempty interrupt source behavior
 Correct Vtune in Figure 5
 Adjust VCO tuning range in section 3.2.5.2

Revision 8

 Add Wafer form ordering information
 Update tools ordering information
 Update Bit Synchronizer description

Phone [phone] Fax: [phone]

© Semtech 2013
All 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 no responsibility or liability whatsoever for any failure or unexpected operation resulting from misuse,
neglect improper installation, repair or improper handling or unusual physical or electrical stress including, but not limited to,
exposure to parameters beyond the specified maximum ratings or operation outside the specified range.

SEMTECH PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR
USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION
OF SEMTECH PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE
CUSTOMER’S OWN RISK. Should a customer purchase or use Semtech products for any such unauthorized application,
the customer shall indemnify and hold Semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless
against all claims, costs damages and attorney fees which could arise.

Rev 8 – February 2013

Page 92 of 92 www.semtech.com