I am trying to use the FatFs middleware but get stuck in HAL_Delay() when trying to turn the power on to SDMMC. Could someone explain why this might be happening or point to a solution for this. I put the backtrace from gdb in the details.

[SPate.4]

#0 0x0800add0 in HAL_Delay (Delay=2) at Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_hal.c:378

#1 0x0800b9ec in SDMMC_PowerState_ON (SDMMCx=0x40012c00)

   at Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_ll_sdmmc.c:316

#2 0x0800c4fe in HAL_SD_InitCard (hsd=0x2000643c <hsd1>) at Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_hal_sd.c:428

#3 0x0800c46c in HAL_SD_Init (hsd=0x2000643c <hsd1>) at Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_hal_sd.c:379

#4 0x08021d9e in BSP_SD_Init () at FATFS/Target/bsp_driver_sd.c:58

#5 0x0800ed46 in SD_initialize (lun=0 '\000') at FATFS/Target/sd_diskio.c:156

#6 0x080169f4 in disk_initialize (pdrv=0 '\000') at Middlewares/Third_Party/FatFs/src/diskio.c:60

#7 0x08019498 in f_mkfs (path=0x20009f5a <SDPath+2> "/", opt=7 '\a', au=0, work=0x2004fdcc, len=512)

   at Middlewares/Third_Party/FatFs/src/ff.c:5334

#8 0x08005a34 in main () at Core/Src/main.c:173

[SPate.4]

I was able to solve this by switching to SysTick for the clock. If anyone knows a solution that doesn't require switching to a SysTick, that would be greatly appreciated.

[Tesla DeLorean]

Not really much to work with here.

Which TIM vs SysTick?

What are the relative priorities/preempt levels for the interrupts?

[Javier1]

if you call HAL_delay() inside an interrupt with higher priority than your sistem tick source (systick or tim) it will wait indefinetly for the ticks that will never happen

And effectively stall your program.

[saeed.poorjandaghi]

It sounds like that you're using RTOS and calling f_mount function when _FS_REENTRANT macrro is enabled (=1) will call ff_cre_syncobj function is syscall.c to create a new sync. object. If f_mount function is called before RTOS init functions it can cause this type of issue. I would suggest that you move f_mount function into your idle task init section.