Hello,
I am working on an application that uses the SDMMC peripheral to read the contents alternating audio files every 150ms. The buffers i have to store the data are large enough to store the entire file in a single burst within RAM. The problem I am running into is that intermittently, the sound "loops" indicating a lockup on the sound subsytem. I've added a small timer in SysTick in order to quantify how long and often this lockup occurs as the logic is running in a lower priority interrupt. I find that the system locks up between 300ms-1200ms. When I listen for this audibly and stop the code, I find that the code is stuck in:
if(BSP_SD_ReadBlocks_DMA((uint32_t*)buff,
(uint32_t) (sector),
count) == MSD_OK)
{
ReadStatus = 0;
/* Wait that the reading process is completed or a timeout occurs */
timeout = HAL_GetTick();
while((ReadStatus == 0) && ((HAL_GetTick() - timeout) < SD_TIMEOUT))
{
}
/* in case of a timeout return error */
if (ReadStatus == 0)
{
res = RES_ERROR;
}
in sd_diskio.c. The project is generated using STM32CubeMX on v1.13 of the processor's firmware. I have tried various methods of troubleshooting this including:
both polling and DMA implementations generated by Cube
increasing and slowing the clock divider for the SDMMC peripheral
enabling and disabling DMA cache maintenance and scratchpad buffers
forcing ISB and DSB while waiting on ReadStatus
defining my buffers in RAM_D1 and not DTCM while also making sure they're on 32 bit boundaries
debugging and putting breakpoints on failure conditions in HAL_SD_IRQHandler()
changing SD_Timeout in sd_diskio.c to see if the hang up time changes
verifying that the data passed to the IDMA is correct in the DMA template generated by Cube
Changing my clock source from PLL1Q running at 64MHz to PLL2R running at 48MHz
enabling and disabling DCache
internal pull ups on the SDMMC lines even though the lines are pulled by external hardware already
reinitializing the SD card
different PCBs/SD cards
changing the maximum output speed on the GPIO peripheral to Very High for the SDMMC pins
disabling LFN functionality to simplify the code execution
verified interrupt priorities
Nothing I seem to change changes the frequency of this problem, nor helps mask it
My interrupt priorities are as follows:
NVIC_SetPriority(SysTick_IRQn, 0);
NVIC_SetPriority(SDMMC1_IRQn, 1);
NVIC_SetPriority(OTG_FS_IRQn, 2);
NVIC_SetPriority(TIM7_IRQn, 3);
NVIC_SetPriority(USART3_IRQn, 4);
NVIC_SetPriority(UART8_IRQn, 5);
NVIC_SetPriority(UART7_IRQn, 5);
NVIC_SetPriority(USART6_IRQn, 5);
NVIC_SetPriority(USART2_IRQn, 5);
NVIC_SetPriority(USART1_IRQn, 5);
NVIC_SetPriority(TIM8_UP_TIM13_IRQn, 6);
All of the USART interrupts in my current test are not running, and user code is being executed in TIM8 that is calling SD car functions. USB is also not initialized. TIM7 is a timer for a DAC to play audio from my buffers
Cube SDMMC settings, with SDMMC1 global interrupt enabled
FATFS settings with DMA template enabled in advanced settings
I have spent weeks trying to troubleshoot this issue across multiple projects using the same processor or one in the family, but it keeps peaking it's little head. Any idea on what I could be missing?
Any help would be appreciated.
