2020-07-28 04:37 PM
I have designed and build a PCB with an STM32F4 and an Micro SD card slot reader on it. It has happened to me that multiple times the board works for a while and then it either burns out the STM or damages the SD card, My problem only occur when an SD card is present and I have tried using multiple different brands but no luck. None of the traces are shorted and the continuity of them are fine. Whenever it is not damaged the STM cannot connect to the SD Card and it returns FR_NOT_READY but when the SDIO pins are set to GPIO outputs then I am able to see the pins working fine. My traces connecting to it include 20 ohm resistors and I activated all of the pin pull ups when generating the code.
Any help on how to start or where to look for is really appreciated!
2020-07-28 07:04 PM
Sure sounds like a hardware error. Can you show your schematic?
What does "burns out the STM" or "damages the SD card" mean in particular? Smoke?
2020-07-28 07:25 PM
I've had such things running for months on end in long term logging applications.
We use really pull-up resistors at the sockets.
User interaction, I could see potential issues with static discharge. Socket well bonded to ground planes/fill under/around socket?
Do you see similar failure on other boards, in similar conditions, or just your own?