AnsweredAssumed Answered

STM32F769 DISCO with FatFS SD makes UART5 and 7 unusable

Question asked by Joerg Wagner on Jan 11, 2018
Latest reply on Jan 12, 2018 by Joerg Wagner

I use CubeF7 1.8.0 and the BSP drivers for SD support. Working (reading and writing files) with SD card is fine.


After initializing SD with:

static void SD_Initialize(void)
  if (isInitialized == 0)
    if (BSP_SD_Init() == MSD_OK)
      isInitialized = 1;

      /* wait until the uSD is plugged */
      while (BSP_SD_IsDetected() != SD_PRESENT) {}


UART5 and UART7 are not usable anymore.

Interrupt does not occur anymore and even a simple

    HAL_StatusTypeDef  hscs = HAL_UART_Receive(&huart5, rxdata, 10, 0x1000);

ends with HAL_TIMEOUT. (A 2nd board sends a string continously)

I also omitted 4 Bit SD, just for testing.


When I make my SD stuff, i.e. reading a config file and then calling


UART5 and UART7 can properly used, with IT or without.

UART6 for instance is not affected by the SD functions.

Other UARTs are not accessible with STM32F769-DISCO, so I don't know if they work or not.


The goal is an application with SD, 3x UARTs, STEmWin, Ethernet. Everything works nice except the

combination of SD and UART5/7.


Any idea?

Thank you, Joerg