Troubleshooting

TX won't connect to RX

• Ensure RX is powered and in pairing mode (hold BOOTSEL for 5 seconds).
• Verify both devices use the same binding phrase (check Serial output for binding UID).
• Check radio wiring (SPI, BUSY, DIO1, RST pins).
• Monitor Serial output (115200 baud) for connection state and error messages.

Pairing fails

• Make sure RX is in pairing mode (hold BOOTSEL for 5 seconds, 60 second timeout).
• Verify binding phrase matches on both devices (check Serial for binding UID).
• Check radio initialization (should see "SX128x ready" in Serial).
• Ensure devices are within range (SX1280 has good range but test close first).

No CRSF output from RX

• Verify RX is connected (check Serial for "CONNECTED" state).
• Check CRSF wiring (GP8 to FC RX, GP9 from FC TX).
• Verify CRSF baudrate is 420000 on flight controller.
• Monitor Serial for "[CRSF OUT]" messages showing frame transmission.

No channel data from RC board

• Verify UART wiring between RC board and TX module (GP8/GP9, 420000 baud).
• Check RC board is powered and sending data.
• Monitor TX Serial for UART protocol messages.
• Verify RC board implementation is correct.

Radio not initializing

• Check all SPI connections (SCK, MOSI, MISO, CS).
• Verify BUSY and DIO1 pins are connected.
• Check RST pin connection.
• Ensure proper power supply (3.3V).
• Check Serial for "SX128x init failed" messages.

Connection drops frequently

• Check RSSI and SNR values in Serial (should be > -90 dBm RSSI).
• Verify antenna connection.
• Check for interference on 2.4GHz band.
• Monitor sync ACK misses (should be 0 when connected).