LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
83 of 130
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8.8 Data Buffer
The LR1121 is equipped with two 255 byte RAM data buffers which are accessible in all modes except sleep mode. One
buffer stores the received payload data, while the other contains the payload data to be transmitted.
The LR1121 automatically controls the data pointers, which means that no base address handling by the user is necessary.
• Data Buffer in Receive Mode:
The received payload data are stored in the RX buffer:
They can be read back using command ReadBuffer8(...) (see 3.7.5 ReadBuffer8)
GetRxbufferStatus(...) reads the pointer to the first byte of the last packet received and the packet
length (see 7.2.11 GetRxBufferStatus).
ClearRxBuffer(...) clears all the data in the LR1121 RX buffer (see 3.7.6 ClearRxBuffer)
• Data Buffer in Transmit Mode:
The payload data to be transmitted shall be written the Tx Buffer using command WriteBuffer8(...) (see 3.7.4
WriteBuffer8)
8.9 RSSI Functionality
The RSSI information of the LR1121 is available either in the radio chain, or after demodulation at the end of the reception
stage. A summary of the RSSI information and their meaning is summarized in table Table 8-26: RSSI Information Origin and
Meaning below:
Refer to each command description for implementation details on the various RSSI fields.
Table 8-26: RSSI Information Origin and Meaning
Command
Modem
Name Description
GetRssiInst(...)
All
RssiInst
Instantaneous RSSI
GetPacketStatus(...)
(G)FSK
RssiSync
Instantaneous RSSI value latched in the (G)FSK demodulator, upon
detection of sync address
RssiAvg
Average RSSI value over the whole payload of the received packet,
determined in the (G)FSK demodulator.
LoRa®
RssiPkt
Measurement of the mean energy at the input of the modem over the
last packet received.
SignalRssiPkt
Estimation of the mean energy of the LoRa signal over the last packet
received. Equivalent to RssiPkt - environment noise
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