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receive(): don't touch FIFO on timeout #98

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Merged
dhalbert merged 2 commits into from
Dec 16, 2025
Merged

receive(): don't touch FIFO on timeout #98

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1477590
receive(): don't touch FIFO on timeout
bablokb Dec 15, 2025
82a7d49
fix formatting
bablokb Dec 15, 2025
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101 changes: 50 additions & 51 deletions adafruit_rfm9x.py
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Original file line number Diff line number Diff line change
Expand Up @@ -816,6 +816,13 @@ def receive(
while not timed_out and not self.rx_done():
if time.monotonic() - start >= timeout:
timed_out = True

if timed_out and not self.rx_done():
# don't touch the FIFO if we want to keep listening
if not keep_listening:
self.idle()
return None

# Payload ready is set, a packet is in the FIFO.
packet = None
# save last RSSI reading
Expand All @@ -826,63 +833,55 @@ def receive(

# Enter idle mode to stop receiving other packets.
self.idle()
if not timed_out:
if self.enable_crc and self.crc_error():
self.crc_error_count += 1
if self.enable_crc and self.crc_error():
self.crc_error_count += 1
else:
# Read the data from the FIFO.
# Read the length of the FIFO.
fifo_length = self._read_u8(_RH_RF95_REG_13_RX_NB_BYTES)
# Handle if the received packet is too small to include the 4 byte
# RadioHead header and at least one byte of data --reject this packet and ignore it.
if fifo_length > 0: # read and clear the FIFO if anything in it
current_addr = self._read_u8(_RH_RF95_REG_10_FIFO_RX_CURRENT_ADDR)
self._write_u8(_RH_RF95_REG_0D_FIFO_ADDR_PTR, current_addr)
packet = bytearray(fifo_length)
# Read the packet.
self._read_into(_RH_RF95_REG_00_FIFO, packet)
if fifo_length < 5:
packet = None
else:
# Read the data from the FIFO.
# Read the length of the FIFO.
fifo_length = self._read_u8(_RH_RF95_REG_13_RX_NB_BYTES)
# Handle if the received packet is too small to include the 4 byte
# RadioHead header and at least one byte of data --reject this packet and ignore it.
if fifo_length > 0: # read and clear the FIFO if anything in it
current_addr = self._read_u8(_RH_RF95_REG_10_FIFO_RX_CURRENT_ADDR)
self._write_u8(_RH_RF95_REG_0D_FIFO_ADDR_PTR, current_addr)
packet = bytearray(fifo_length)
# Read the packet.
self._read_into(_RH_RF95_REG_00_FIFO, packet)
# Clear interrupt.
self._write_u8(_RH_RF95_REG_12_IRQ_FLAGS, 0xFF)
if fifo_length < 5:
if self.node != _RH_BROADCAST_ADDRESS and packet[0] not in {
_RH_BROADCAST_ADDRESS,
self.node,
}:
packet = None
else:
if self.node != _RH_BROADCAST_ADDRESS and packet[0] not in {
_RH_BROADCAST_ADDRESS,
self.node,
}:
# send ACK unless this was an ACK or a broadcast
elif (
with_ack
and ((packet[3] & _RH_FLAGS_ACK) == 0)
and (packet[0] != _RH_BROADCAST_ADDRESS)
):
# delay before sending Ack to give receiver a chance to get ready
if self.ack_delay is not None:
time.sleep(self.ack_delay)
# send ACK packet to sender (data is b'!')
self.send(
b"!",
destination=packet[1],
node=packet[0],
identifier=packet[2],
flags=(packet[3] | _RH_FLAGS_ACK),
)
# reject Retries if we have seen this idetifier from this source before
if (self.seen_ids[packet[1]] == packet[2]) and (packet[3] & _RH_FLAGS_RETRY):
packet = None
# send ACK unless this was an ACK or a broadcast
elif (
with_ack
and ((packet[3] & _RH_FLAGS_ACK) == 0)
and (packet[0] != _RH_BROADCAST_ADDRESS)
):
# delay before sending Ack to give receiver a chance to get ready
if self.ack_delay is not None:
time.sleep(self.ack_delay)
# send ACK packet to sender (data is b'!')
self.send(
b"!",
destination=packet[1],
node=packet[0],
identifier=packet[2],
flags=(packet[3] | _RH_FLAGS_ACK),
)
# reject Retries if we have seen this idetifier from this source before
if (self.seen_ids[packet[1]] == packet[2]) and (
packet[3] & _RH_FLAGS_RETRY
):
packet = None
else: # save the packet identifier for this source
self.seen_ids[packet[1]] = packet[2]
if not with_header and packet is not None: # skip the header if not wanted
packet = packet[4:]
else: # save the packet identifier for this source
self.seen_ids[packet[1]] = packet[2]
if not with_header and packet is not None: # skip the header if not wanted
packet = packet[4:]
# Listen again if necessary and return the result packet.
if keep_listening:
self.listen()
else:
# Enter idle mode to stop receiving other packets.
self.idle()
# Clear interrupt.
self._write_u8(_RH_RF95_REG_12_IRQ_FLAGS, 0xFF)
return packet