SPI Display works only when code is launched via STM32CubeIDE

[T1P0Z]

Hi everyone, 

I'm using the STM32F407G-DISC1 development board, which is mounted on a custom PCB I designed and powered by an external power supply. I've connected a Capacitive Graphic LCD Display Module (EVE3-70G-BLM-TPC-F32) to the custom PCB via SPI. The display and touch functionality work perfectly when the STM32 is connected to a PC, and the code runs on the board as expected. Interestingly, if I first connect the dev board to the PC, run the code via STM32CubeIDE, and then disconnect it from the PC, both the display and touch functionality continue to work. However, when I power the board directly with the external power supply, the display powers on, but the touchscreen stops working.

[Andrew Neil]

What testing/investigation/debugging have you done to find what's different between the two cases?

Maybe power supply or grounding issues?

[T1P0Z]

Hi Andrew,

I verified that BOOT0 is set to LOW, as expected. I also attempted to switch the project from Debug to Release mode.

Additionally, I did some physical trial-and-error debugging to check if the touch functionality works both with and without the PC connected to the development board.

[T1P0Z]

However, I'm unsure where the issue lies. The SPI communication functions as expected, even after disconnecting the development board from the PC, but only if the software was flashed to the board before disconnecting.

The problem occurs when I power off the device and turn it back on. In this case, while the display works and shows the correct output, the touchscreen just wont respond.