I wired 4 digital pins from the Arduino to the inputs of the first analog switch IC, and then the four inputs and outputs to the pads of the Baofeng UV5R buttons (1,2,3 and SCAN)

I whipped my code into shape and the results were great! I'm using a 400ms delay for holding down the buttons, and between the button presses. But I reckon I can shorten that down quite a bit.

The wiring is a dog. I'm not loving it. The astute among you might think this is a good project for a PCB, and forgive the Eagle gore but I've had a crack...

This was my idea for a carrier board to hold the Arduino, and give me solder pads on the sides to hold the wires for the buttons. I might still go this route - but I'm in a hurry so I think I'll plunge ahead with hand wiring the whole thing!

Regardless, this test is awesome, and proves the concept even further. The idea is that the front of the unit will show the original Baofeng screen (just as a reference to the currently set frequency) as well as the OLED screen, the rotary encoder on top, with the original Baofeng power / volume knob also up there.

The Arduino Mega clone I'm using can take up to 18v in, so I'll be able to power it directly from the 2s Lipo battery that the UV5R uses (I've added a wire after the Baofeng radio switch, that will power the Arduino) I'll be adding a USB-C charger to a couple 18650's to take care of power, and the original Baofeng screen will still show the battery level, which is pretty neat.

Once electronics are done, I'll press on with the case! I've started on it, but the only cad model I could find is a shitty STL - and I'm having no luck converting into a parametric model. If anyone has any tips or is able to help - please reach out! I'll attach a link to the STL.

STL from - https://sketchfab.com/3d-models/nokota-radio-cyberpunk-2077-641dc25a8e25498ea9a52b71153b7dab