As you may read it on the corresponding article, our copter runs a Linux kernel with Ubuntu, and has Wifi. We have thus full access to the copter by SSH. However, it’s not the best user-friendly way to control such a system. Fortunately with the original Oktokopter that we have, there was a remote control: the Spektrum DX7. Thanks to the code of the last year project, Heliokter, we could implement quickly the use of this remote control.
With the big impressive radio, we have a little receiver, which gets the information through the 2.4Ghz channel communication and transforms it into data sent by the RS232 115200 bps protocol. Our copter take on board this receiver, connected to our PCB. The STM32 is then in charge of the transmission of the data to the Gumstix.
The Gumstix receives thus commands of thrust, pitch, roll and yaw in our high-level control, which uses this information to move the copter. The precision of this information is quite good: each axis has approximately a scale from 0 to 700.
We also use a little protocol to start or stop the motors. As the Gumstix starts its tasks at startup, we are able to control the copter using only the remote control.