This is the second part of a tutorial about BLE, micro:bits and UART.
I assume that you have seen and understood the first part, to be found here:
This is the Ringbit car:
It costs about $25, not including a micro:bit v2, which should cost less than $20. It is fairly easy to assemble, but it does not look very sturdy. There are many alternatives available in a similar price range. They all operate more or less the same.
The .aia .hex from the previous part that you can use to start and which covers the basic connection via BLE to a micro:bit and basic communication with the micro:bit via UART are these:
microbit-UART_RW.hex (1.5 MB)
BTstarter.aia (191.3 KB)
The description for this tutorial can be found in the attached PDF:
microbitRingbitCar.pdf (859.7 KB)