STM32F302K8 driven system with 4 pin header programming

Thread Starter


Joined Feb 23, 2024
Hi All,

I have a small PCB circuit with a brushless motor being driven by a Arm Cortex STM32F302K8 microproccessor it also contains mosfets and microswitches. This PCB has a 4 pin header for an external programming card, but this programming card has not been released and it has been 2 years, the card is designed to allow adjustment of certain parameters, RPM, active braking, among others. I have been trying to figure out what protocol the header is using with a view to read the data onto a computer and make adjustments before loading it back into the processors flash memory.

From what I can imagine the programming card is parasitic power from the main system as it is designed to be done on the fly.

I have figured out what pins on the chip the 4 pin header connects to but I don't know the protocol, I thought it was USART but the voltage for the Tx pin is too high.

Pin 1 is a direct ground.
Pin 2 is connected to Pin 27 which goes to PB4 and when the system is on has 3.3v consistently
Pin 3 is connected to Pin 28 which goes to PB5 and has 0v
Pin 4 is grounded when the system is off but has 2 resistors on it. adding to 173kohms, and when system is on has 12v

This is the datasheet for the processor

Anyone got any input, is this even doable? I am a mac user, so anything that people come up with needs to be Mac compatible.