Having assembled the body of the GoPiGo Robot Car, it is now a good opportunity to learn more about the brain (CPU) controlling Dexter Industries' GoPiGo board, which is an ATMEGA328 microcontroller.
Micro-controllers function very much like computers sending, receiving and executing commands that are stored in the microcontroller's flash memory. The more memory, the more lines of commands you can store and the ATMEGA328 microcontroller has built-in 32KB flash memory and 2KB SRAM (static random-access memory) to help the CPU retrieve commands faster.

Thanks to the ATMEGA328 microcontroller, which features serial interface, 23 GPIOS and SPI serial port, the GoPiGo board can communicate with computer hardware and software. That's where a single board computer like the Raspberry Pi comes in handy being the size of a palm. The Raspberry Pi fits nicely on top of the GoPiGo board, connecting with one another via I2C interface and enabling the communication of commands to the GoPiGo's brain (the ATMEGA328 microcontroller).
The GoPiGo board features three headers: Servo Header, Raspberry Pi Header and ISP Header. The board also features Raspberry Pi prototyping pins, Level Conversion chip and TB6612FNG motor controller, which allows you control two DC motors independently form each other.

There are several analog and digital ports on the GoPiGo board for connecting sensors like temperature, accelerometer and GPS. On the back of the board is where the microcontroller is located, as well as two Optical Encoders with 18 pulse counts per rotation which help the GoPiGo move precisely in a straight line.
The GoPiGo board operates with voltages between 7V and 12V; hence the battery pack carrying eight 1.5V batteries to power both motors, ultrasonic sensor, servo and Raspberry Pi (the Raspberry Pi itself uses 3.3V).