LED Status
The 305ap has three LEDs (red, green, and blue), all active-low (GPIO LOW = on).
| Color | GPIO | Pin |
|---|---|---|
| Red | PD9 | — |
| Green | PB12 | — |
| Blue | PE12 | — |
PX4 controls these LEDs to communicate system state. The patterns below reflect standard PX4 LED behavior.
Patterns
Boot Sequence
| Pattern | Meaning |
|---|---|
| Blue blink (first 5 s after power-up) | Bootloader active, waiting for firmware upload |
| Green solid (during an upload) | Bootloader writing firmware |
| All LEDs on briefly | NuttX initializing |
| Blue slow blink | PX4 starting up, sensors initializing |
Normal Operation
| Pattern | Meaning |
|---|---|
| Blue breathing (slow pulse) | Disarmed, no GPS |
| Green solid | GPS lock acquired, ready to arm |
| Green + Blue | Disarmed, GPS lock, ready |
| Green fast blink | Armed |
| Red + Blue alternating | Error condition — check QGC for details |
| Red solid | Critical error |
Arming States
| LED state | Meaning |
|---|---|
| Green slow blink | Pre-arm checks passing, waiting for arm command |
| Green fast blink | Armed — props may be spinning |
| Red blink | Pre-arm check failing |
Diagnosing Errors
If the red LED is blinking, connect to QGroundControl and check:
- Status bar: error flags appear at the top
- MAVLink Console →
commander status: shows what is blocking arming - MAVLink Console →
listener vehicle_status: detailed system state
No LEDs at All
If no LEDs illuminate after power-on:
- Verify power input voltage is within spec
- Check the SD card is inserted (missing SD card does not prevent boot but triggers an error)
- Try re-flashing firmware via DFU mode