Datasheet
Table Of Contents
- 1. General Description
- 2. Electrical Characteristics
- 3. SX1272/73 Features
- 4. SX1272/73 Digital Electronics
- 4.1. The LoRaTM Modem
- 4.2. FSK/OOK Modem
- 4.2.1. Bit Rate Setting
- 4.2.2. FSK/OOK Transmission
- 4.2.3. FSK/OOK Reception
- 4.2.4. Operating Modes in FSK/OOK Mode
- 4.2.5. General Overview
- 4.2.6. Startup Times
- 4.2.7. Receiver Startup Options
- 4.2.8. Receiver Restart Methods
- 4.2.9. Top Level Sequencer
- 4.2.10. Data Processing in FSK/OOK Mode
- 4.2.11. FIFO
- 4.2.12. Digital IO Pins Mapping
- 4.2.13. Continuous Mode
- 4.2.14. Packet Mode
- 4.2.15. io-homecontrol® Compatibility Mode
- 4.3. SPI Interface
- 5. SX1272/73 Analog & RF Frontend Electronics
- 6. Description of the Registers
- 7. Application Information
- 8. Packaging Information
- 9. Revision History
www.semtech.comPage 50
SX1272/73
WIRELESS, SENSING & TIMING DATASHEET
Rev. 2 - July 2014
©2014 Semtech Corporation
The calibration process takes approximately 10 ms.
4.2.3.9. Timeout Function
The SX1272/73 includes a Timeout function, which allows the automation of a duty-cycled recceive oprtation where the
radio periodically wakes from sleep mode into receiver mode.
Timeout interrupt is generated TimeoutRxRssi x 16 x Tbit after switching to Rx mode if the Rssi flag does not raise
within this time frame (RssiValue > RssiThreshold).
Timeout interrupt is generated TimeoutRxPreamble x 16 x Tbit after switching to Rx mode if the PreambleDetect flag
does not raise within this time frame.
Timeout interrupt is generated TimeoutSignalSync x 16 x Tbit after switching to Rx mode if the SyncAddress flag does
not raise within this time frame.
This timeout interrupt can be used to warn the companion processor to shut down the receiver and return to a lower power
mode. To become active, these timeouts must also be enabled by setting the correct RxTrigger parameters in
RegRxConfig:
Table 20 RxTrigger Settings to Enable Timeout Interrupts
4.2.4. Operating Modes in FSK/OOK Mode
4.2.5. General Overview
The SX1272/73 has several working modes, manually programmed in RegOpMode. Fully automated mode selection,
packet transmission and reception is also possible using the Top Level Sequencer described in Section
4.2.9.
Table 21 Basic Transceiver Modes
When switching from a mode to another the sub-blocks are woken up according to a pre-defined optimized sequence.
Receiver
Triggering Event
RxTrigger
(2:0)
Timeout on
Rssi
Timeout on
Preamble
Timeout on
SyncAddress
None 000 Off Off
Active
Rssi Interrupt 001 Active Off
PreambleDetect 110 Off Active
Rssi Interrupt & PreambleDetect 111 Active Active
Mode Selected mode Symbol Enabled blocks
000 Sleep mode Sleep None
001 Standby mode Stdby Top regulator and crystal oscillator
010 Frequency synthesiser to Tx
frequency
FSTx Frequency synthesizer at Tx frequency (Frf)
011 Transmit mode Tx Frequency synthesizer and transmitter
100 Frequency synthesiser to Rx
frequency
FSRx Frequency synthesizer at frequency for reception (Frf-IF)
101 Receive mode Rx Frequency synthesizer and receiver