2022-01-13 07:37 AM
Hi
I created my own board with a STM32F411RE microcontroller. I can program it normally with a ST-Link v2 probe, the program works correctly.
But from time to time when I disconnect this probe the board stops working. Can someone explain me why?
On my card I have a SSD1306 screen, which when I start the card without the JTAG probe either it does not turn on, or it turns on but with the writing reversed.
Thank you for your answer.
2022-01-13 11:45 AM
Do you have a decoupling cap on NRST? Probably just noise introduced when you disconnect signals in a random manner.
It sounds like the SSD1306 might need some time to boot up before you interface with it. Try adding a delay before doing any access.
2022-01-13 01:01 PM
State of BOOTx pins?
Sufficient time for the OLED to reset and be viable?
Pins and Clocks enabled?
2022-01-13 10:45 PM
I have a decouping cap (of 100nF) just next to the push button. Should I put it closer to the microcontroller pin?
2022-01-13 10:48 PM
The BOOT0 is connect to the GND with 10k resistor.
I will try to put a longer time before the initialization of the screen.
I activate HSE and I have a oscilattor which should work at 8MHz, but I haven't taken the time to check it yet.
2022-01-14 06:16 AM
Technically, yes, it should be closer to the MCU, but I doubt that is the issue.
Put a scope on NRST/VDD and see what's occurring.