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F767 micro SD card freezes

Question asked by smith.greg.005 on Feb 12, 2018

I'm experiencing random freezing of the micro SD card on a custom board, running the STM32F767II.

During read operations, occasionally communications is lost to the card and the driver code will experience repeating timeouts.

Some more details of the app:

- code generated by the latest Cube App and F7 firmware

- SDMMC1 using DMA2 streams 3 and 6; 4 bit mode, PLL48CLK clock and clock divider of 1

- DMA interrupt priority of 12

- SDMMC int priority of 14

- SDRAM and LTDC

- FreeRTOS 

- Fatfs library with re-entrancy enabled (2 tasks are accessing the card)

 

The generated code was patched to correctly init the card (as per forum posts) but is otherwise unmodified.

 

The board is 4 layer, with the required pullups and a series resistor on clock line. Layout was done taking into account the ST recommendations.

 

Have tried multiple sd cards and multiple PCBs, all giving the same results.

 

Anyone got any suggestions?

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