Built a flex PCB “brain implant” to upgrade the UV-K5 radio’s MCU

Hey everyone!

I’ve been tinkering away on a little evening project for a while now and wanted to share it here. The Quansheng UV-K5 handheld radio is fun to hack on, but its original MCU only had 64 kB of flash memory. Not enough to run all the cool community-made features at once.

So, I designed a tiny flex PCB “implant” that lets me replace the stock chip with an STM32G0C1CET (512 kB flash, 144 kB RAM). It involved a lot of signal remapping, flex board experiments, and of course plenty of solder fumes....but in the end it worked!