Hello,
I'm using a custom board based on a STM32H735 with various GPIO inputs and outputs. The STM32 is packaged as a 0.5mil pitch BGA and the board assembly has been outsourced.
I'm able to flash a program on the MCU and debug it by adding breakpoints and visualizing registers values. However, none of the GPIO is working: I cannot drive a LED nor read a button input state. The registers are set as expected when using the HAL to set/reset a GPIO output. I've tried to bypass the HAL and write directly on the registers MODER and ODR, and the IDR register value change as expected. On top of that, I have no trouble driving a GPIO output on my STM32H735 demo board, so I don't think the issue come from the software.
I have 6 LEDs on different GPIO ports, and I cannot drive a single one of them. I also have three boards, I'm able to flash and debug all of them, but not a single GPIO.
It looks as if the GPIOs of the MCU where somehow not connected to the LEDs and buttons of my board. It could be explained if the 0.5mil BGA has been badly soldered, but I can communicate with my 3 boards through the JTAG, and not a single one of the GPIO I tested on my boards are working. This seems thus improbable to me that the issue come from some soldering/reflowing issue, as the JTAG is never impacted.
Do you have any idea on where the issue could come from, or any insight on where I should look at?
Thanks for your help.
T.
