A yellow flashing light indicates that a safety pre-check must be completed in order to properly arm and use the copter (note that this procedure is for your own safety).
To see what has caused Pre-Arm safety check failures.
- Connect your Flight Controller to Your Computer via the USB port.
- Start Mission Planner and select the “Connect” button on the upper right of the page.
- Turn on your radio transmitter and hold your throttle down and to the right (normal arming procedure).
- The first cause of the Pre-Arm Safety Check failure will be displayed in red on the HUD window.
- Address and correct each problem that is reported when you attempt to arm as above.
- When all problems have been corrected, you will see verification of “Arming” in the HUD window.
- You can then disconnect from your computer and have good assurance that arming will proceed normally.
To fix specific Pre-Arm check failures.
- If Radio Calibration check fails re-do the Radio Calibration.
- If Accelerometer Calibration check fails re-do the Accel Calibration.
- If there is a Compass failure try to re-do the Compass’s Live Calibration.
- If the Barometer check fails then your board likely has a hardware problem with the barometer.
- If the GPS position check fails
- Wait for your GPS’s hdop to drop below 2.0 before attempting to arm.You can make this more easily visible in the Mission Planner’s Flight Data screen’s Quick area.
- Disable the Geofence in the Mission Planner’s Config/Tuning >> Geofence screen
- Arm in Stabilize mode and switch to Loiter later (this is not recommended because a good GPS position is required for Loiter and the hdop is a good indication that the position is good)
- increase the GPS_HDOP_GOOD parameter from 200 to 250 (this is also not recommended for the same reasons as the point above) If the board voltage check fails: If the board voltage check fails:
8. If the board voltage check fails:
- check the BEC being used to supply voltage to the APM is producing between 4.5 and 5.5 volts (the closer to 5V the better)
- check if any peripherals that are being powered by the APM have too high a current draw.
9. If Channel 7 was set to the same thing as Channel 8, change one of them using the Mission Planner’s Config/Tuning >> APM:Copter Pids screen
There is actually a way to deactivate these pre-arm safety checks (not recommended).
If you are confident that the pre-arm check failure is not a real problem you can disable the checks by:
- Connecting your APM/PX4 to the mission planner
- Go to Mission Planner’s Config/Tuning >> Standard Params screen
- set the Arming Check drop-down to “Disabled” or if you are using AC3.1 (or higher) you can Skip the item that is causing the failure.
- Push the “Write Params” button
Ideally however you should determine the cause of the pre-arm failure and if it can be resolved, return the Arming Check parameter back to “Enabled”
For more information about this please click here.