To configure the ardupilot/arduflyer for a tricopter you first need to load the tricopter firmware on the board (mine came with the quad firmware out of the box).
In theory, you can use mission planner to do this but for my board at least I consistently received an error when trying to load the firmware that way. I fell back to using the Arduino IDE to compile and load the firmware. This guide covers the process nicely. Basically you:
- Download a customized version of the Arduino IDE and a copy of the arducopter source code
- Copy the ArduCopter and libraries folders into your Arduino sketchbook folder
- Run Arduino set the chip, set the com port and open the arducopter sketch
- Edit the APM_Config.h file to set the FRAME_CONFIG to TRI_FRAME
- Compile and load the code
Once you have the board updated and configured for a tricopter you need to do a number of configuration steps before the board will allow itself to be armed. These include:
- Use ‘Terminal’ in Mission Planner run ‘erase’ then ‘reset’ as detailed here
- Under configuration, calibrate your receiver, calibrate your compass, calibrate accelerometer
- Do an automatic ESC calibration
You should now be able to arm your motors. Detail instructions are here but essentially, hold the left stick to the bottom right for 4-6 seconds (the red LED switches from flashing to solid).
You can now add props and arm the tricopter. Turn on very light throttle and verify all of the props are moving air in the correct direction. If any motor is spinning the wrong direction swap two (of the three) power leads going to the motor to reverse its direction.
Now that the props spin the right way; with very light throttle try rotating the tricopter to verify the yaw servo moves the correct way. On my tricopter it didn’t so I reversed the movement by setting RC_7REV to -1 under the advanced configuration settings of mission planner.