This project provides firmware that runs on an arduino. This firmware, coupled with an arduino, provides a serial (UART) interface for outputting PWM signals. Something like a raspberry pi has lots of processing power and I/O; but it can't reliably drive PWM outputs for servos etc. Due to the PWM being done in software, any slight lag will effect the precise timing required.
By sending the steering and motor outputs over UART to a real time microcontroller, reliability can be ensured. This is because these microcontrollers are specifically designed for stuff like this with very precise timing. The firmware also reports the voltage of a battery; which is great for remote monitoring and safety. I created this for use in our machine learning car.
It's fairly straight forward to use. The PWM output and voltage monitoring pins are in configurable variables at the start of the program. Specify which pins you're using; bear in mind the voltage monitor must be an analog input.
If the maximum voltage of the battery is less than your microcontroller's operating voltage no extra hardware is needed. Just splice a wire into where you want to measure and connect it to the arduino's pin. For LiPo and other multi cell batteries, it is generally only necessary to monitor a single cell. Simply tap into the first cell on the balance connector. If you need a higher voltage lookup how to make a voltage divider to measure battery on arduino.
The steering pin will output a PWM signal using Ardiuno's built in servo library. It will drive practically any servo.
The motor controller pin will output a PWM signal using the arduino servo library. This means it will drive most servos (ie throttle for an IC engine) or most ESC's.
You can send it two commands via UART, "motor,x" to control motor output and "steer,x". X is usually a value between 40 and 150 as the input centers around 90. Car-controller also continusously sends back a measured voltage over the UART when the correct flag is set. If the debug flag is set to true when uploaded, it sends debug messages over UART.
As with all my projects this is released under a GNU GPLv3 or later license in the hope it will be useful.