BU04 LoRa AT Command Troubleshooting
Module Not Responding
| Symptom | Fix |
|---|---|
| No response to AT | Baud rate mismatch — default 9600, try 115200 |
| Garbage response | Send AT followed by CR+LF (not just AT) |
| BUSY after every cmd | Send AT+RESET first, wait 2s |
Common AT Commands
| Command | Function |
|---|---|
| AT | Test communication |
| AT+ADDR? | Read device address |
| AT+CH=8 | Set channel to 8 |
| AT+POWER=22 | Set TX power to 22 dBm (max) |
| AT+RELAY=1,1 | Turn relay 1 ON |
| AT+RELAY=1,0 | Turn relay 1 OFF |
Relay Not Switching
- Relays need separate power supply — the LoRa module does not power the coil
- Try AT+RELAYMODE=1,1 to invert logic (active HIGH vs LOW)
- BU04 relays rated 10A/250VAC — exceeding this welds contacts
Range Issues
- Set TX power to max: AT+POWER=22
- Upgrade spring antenna to external SMA for >500m range
- Keep antenna away from metal enclosures and relay wiring