SX1276/77/78/79
WIRELESS, SENSING & TIMING
DATASHEET
of interest, for instance a calibration should be launched with Frf set to 868.3 MHz if the high frequency port
supports communication in this frequency band. Conversely if the product is used at 169 MHz, the calibration
should be repeated with Frf=169MHz
- FormerTemp and TempChange in SX1276/77/79 are frequency-specific and the IC keeps a copy of these
variables when switching between the low frequency and the high frequency domains (along with the
corresponding calibration values, stored in test registers)
- FormerTemp and TempChange cannot be read in Sleep mode (although they are saved). They should be read in
Standby mode
4.2.3.9. Timeout Function
The SX1276/77/78/79 includes a Timeout function, which allows it to automatically shut-down the receiver after a receive
sequence and therefore save energy.
Timeout interrupt is generated 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 21 RxTrigger Settings to Enable Timeout Interrupts
Receiver
Triggering Event
None
Rssi Interrupt
PreambleDetect
Rssi Interrupt & PreambleDetect
RxTrigger
(2:0)
000
001
110
111
Timeout on
Rssi
Off
Active
Off
Active
Timeout on
Preamble
Off
Off
Active
Active
Timeout on
SyncAddress
Active
4.2.4. Operating Modes in FSK/OOK Mode
The SX1276/77/78/79 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 4.2.8.
Table 22 Basic Transceiver Modes
Mode
000
001
010
011
Selected mode
Sleep mode
Standby mode
Frequency synthesiser to Tx
frequency
Transmit mode
Symbol
Sleep
Stdby
Enabled blocks
None
Top regulator and crystal oscillator
FSTx
Frequency synthesizer at Tx frequency (Frf)
Tx
Frequency synthesizer and transmitter
Rev. 4 - March 2015
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