As part of my involvement in hacking toys and with the release of the new Raspberry PI 3A+ I decided to upgrade my microbit powered toy car to have a Raspberry PI at its core.
The humble started out being a very cheap radio controlled 4 wheel drive car, that was advertised as being waterproof, this I didn't check out but converted it originally to use the BBC Microbit as a controller.
I then upgraded it as to use the RPI 3A+.
I wanted to use as much as possible of the car and managed to use the original battery power pack supplied for the Microbit version.
But moving to the RPI 3 I upgraded the power to use a 7.4v 2S Lipo as its power-source, split so it gave the PI a stabilised 5v and the motors were fed with the full 7.4v available.
I used the 4tronix piconzero as a motor driver, this is also a good board to use to drive Neopixels which i intend to add later.
I fitted a tiny power regulator board which outputs to USB so I could power the RPI 3A+ direct from a standard usb lead.
The one USB port available on the RPI3A+ I plugged in a Candy Controller dongle so I could test remote control, and add other functions by remote.
It all fitted nicely into the chassis, and was a really cost effective way of creating a 4 wheel drive Raspberry PI powered car.
If there is anything that wasnt ideal the gear ratio of the motors to the wheels makes the car run a little quickly, however with the analog control available using pwm available on the piconzero board some simple control using the inputs library rectified the rapid acceleration to be smoother. Overall I was pleased with the results and the entire hack only took about an hour to finish and get a working model as far as the hardware was concerned, then probably another hour was used to get basic remote control via software and the remote controller to work.
Fitting a main on off switch is always a good idea for the power, so it can act as a master switch for both the PI and motor circuits.
I did find it would be easy enough to fit the original cover of the toy on top of the PI3A+ in the chassis, with the use of some pcb standoffs, keeping the wiring safe and avoiding damage.