Incorrect SNR parsing in _read_packet of LoRa SX1262 driver

[hlym123]

🐛 Bug Description

micropython/lora/lora-sx126x/lora/sx126x.py, line: 599

In sx1262.py, the SNR value is parsed incorrectly in _read_packet. The driver currently does:

rx_packet.snr = pkt_status[2]  # Incorrect

pkt_status[2] is a signed 8-bit integer in two’s complement format (unit: dB × 4), and should be converted before use.

raw_snr = pkt_status[2]
if raw_snr >= 128:
    raw_snr -= 256  # convert to int8

[dpgeorge]

@projectgus FYI

[projectgus]

Thanks @hlym123, will fix.