Building an Autonomous Vehicle: The Batmobile
Nate 
Control Electronics - Brain
The Brain is a SAMD21 Mini. It sends commands over the I2C bus to the locomotion controller and debug LCD.
4-pin JST connector at the top of the image: We used a 4-wire bus (5V, GND, SDA, SCL) for communication and had various taps throughout the bus to allow devices to be attached. This worked really well and allowed for devices to be moved around when needed.
4-pin JST connector to the left: This was four wires to the button. To tell the vehicle to begin navigating under autonomous control, we used a metal momentary push button that illuminates when everything is online and happy. The human presses the button twice, and the car commences racing.
Big gray handle: This was the original forward and reverse knob that we reused to control the direction switch on the motor controller (two pins when shorted together caused one direction, when open caused the other direction).
The massive and poorly written control code for the Brain can be found here.
EEPROM for Waypoints
The SAMD21 does not have internal EEPROM. Because we needed to store GPS waypoints and other configuration data to non-volatile memory, we used an external I2C EEPROM. Yes, you can use something called emulated EEPROM on the SAMD21, but, every time you reprogram the board, you will overwrite anything previously stored in emulated EEPROM. The external EEPROM made it much easier to store and recall waypoints and settings without having to mash together in the main control code.