Happily an updated version of the Raspberry Pi A+ was released at the end of 2018. This has the newer CPU, WiFi and Bluetooth of the Raspberry Pi 3 B+, but in a smaller package. Of course this does come with some sacrifices, only half the memory, a slightly lower top CPU speed and no Ethernet port. But the pros definitely out way the cons.
With the brain sorted the next item to think about is driving the motors, as every challenge in PiWars requires the robot to move. I've collected a number of motor drivers over the years, but one I've yet to get around to trying is the PiBorg Thunderborg. This motor controller can easily drive two motors, can be powered from a wide range of voltages and also produces a 5V output to power the Raspberry Pi itself. This helps keep down number of other components I need to fit into the case.
With these two components selected I placed them in Wall-E's chassis in a variety of positions, trying to determine where they should go. I wanted to minimise the impact they may have on other items I would add later, but not place them in some strange positions that they would be complicated to mount. So after a few attempts it looked like the best place for the Raspberry Pi is where the original PCB was, with the motor controller fitting between it and the motors.
|Squeezing components into Wall-E's chassis
|Initial Raspberry Pi and motor mounts designs