PX4
[Bug] Crazyflie 2.1 - M4 Motor Runs Uncontrollably at Startup, Preventing QGroundControl Connection
Describe the bug
I encountered a critical issue when flashing the PX4 firmware onto a Crazyflie 2.1. Upon startup, the M4 motor spins uncontrollably at full speed, draining the battery excessively and preventing a stable connection with QGroundControl (QGC).
This issue makes it impossible to establish proper control over the drone and blocks further testing or integration.
Possible Causes:
- Incorrect motor initialization or PWM configuration for Crazyflie in PX4 firmware.
Request for Support:
I would appreciate any guidance on debugging this further or potential fixes. Let me know if additional logs or testing are required.
To Reproduce
- Follow the official PX4 documentation to build and flash the firmware: Crazyflie 2.1 PX4 Documentation
- Power on the Crazyflie 2.1 after successful flashing.
- Observe that M4 starts running at full power immediately.
- Try connecting to QGroundControl → The connection fails.
Actual Behavior:
- Motors should remain idle at startup until proper commands are received.
- QGC should successfully establish a connection with Crazyflie.
Expected behavior
- M4 motor starts spinning uncontrollably as soon as the drone is powered on.
- Battery drains rapidly.
- Unable to connect the drone to QGroundControl.
Screenshot / Media
https://github.com/user-attachments/assets/c4b50c82-9013-4bd8-a587-dc9125cf075b
Flight Log
No response
Software Version
- Hardware: Crazyflie 2.1
- Firmware Version: PX4 (latest stable & master branch tested)
- Build Instructions Followed: Per PX4 official documentation
Flight controller
No response
Vehicle type
None
How are the different components wired up (including port information)
No response
Additional context
- This issue has been reported in the PX4 forum but remains unresolved since November 2023: PX4 Forum Discussion
- The Crazyflie 2.1 should only fly in Stabilized mode, as documented, but this issue prevents any flight testing.
- No custom modifications were made; this behavior occurs with a clean PX4 build.
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/px4-autopilot-on-the-crazyflie-2-1/35588/4
Hey! Running into the same issue. Curious -- have you had any luck resolving it (maybe by reverting to an older version)?
