Torqeedo Interface DUNE task

To enable communication between the IMC messages from DUNE, and the CAN bus used by the Torqeedo Interface Board, a new task has been created for use in the Otter. DUNE was also missing support for CAN, so this had to be added.

The task is of the periodic type, which limits how often it runs. The frequency of the task can be set with the parameter Execution Frequency, as all Periodic DUNE tasks can. The Torqeedo Interface Board typically sends 20-25 CAN messages per second, so the task has to be run with a frequency greater than this. In order to run the motors, it has to receive throttle controls at least once per second.

One run of the task either reads a CAN message, or writes to the motors. To limit how often the motor is written to, a parameter called Motor write divider is set. A counter then count every time the task is run, and when Motor write divider is reached, the motors are written to, and the counter is reset. An example of this could be:

You want the motor to be written to 4 times a second. Say you have set "Execution Frequency = 40", then you would have an "Motor write divider" of 40/4=10.

The task uses the SocketCAN implementation in DUNE to communicate with the CAN bus.