Arduino for STM32

Posted: **Tue Feb 02, 2021 2:46 pm**

Hi,

I am trying to run an SD card at a minimum of 48KB/s, however the maximum speed it can run is 42KB/s. One problem that might be causing it is that the SD cards only write correctly at the 8MHz SDMMC1 clock, if i try to increase it to 32MHz/16Mhz.etc the SD card stops writing?

Code: Select all


extern "C" void SystemClock_Config(void) {
    RCC_OscInitTypeDef RCC_OscInitStruct = {};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {};
    RCC_PeriphCLKInitTypeDef PeriphClkInit = { 0 };

    /* Configure LSE Drive Capability */
    HAL_PWR_EnableBkUpAccess();
    __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
    /* Initializes the CPU, AHB and APB busses clocks */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE | RCC_OSCILLATORTYPE_MSI;
    RCC_OscInitStruct.LSEState = RCC_LSE_ON;
    RCC_OscInitStruct.MSIState = RCC_MSI_ON;
    RCC_OscInitStruct.MSICalibrationValue = 0;
    RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
    RCC_OscInitStruct.PLL.PLLM = 1;
    RCC_OscInitStruct.PLL.PLLN = 40;
    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
    RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
    RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        Error_Handler();
    }
    /* Initializes the CPU, AHB and APB busses clocks */
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
        | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK) {
        Error_Handler();
    }

    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_SDMMC1;
    PeriphClkInit.Sdmmc1ClockSelection = RCC_SDMMC1CLKSOURCE_PLLSAI1;
    PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_MSI;
    PeriphClkInit.PLLSAI1.PLLSAI1M = 1;
    PeriphClkInit.PLLSAI1.PLLSAI1N = 16;
    PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV17;
    PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV8;
    PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV2;
    PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_SAI1CLK | RCC_PLLSAI1_ADC1CLK | RCC_PLLSAI1_48M2CLK;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
        Error_Handler();
    }


    /* Configure the main internal regulator output voltage */
    if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK) {
        Error_Handler();
    }

    /* Enable MSI Auto calibration */
    HAL_RCCEx_EnableMSIPLLMode();


}

When i try to increase RCC_PLLQ_DIV8 to RCC_PLLQ_DIV2 (8MHz to 32MHz) the sd card refuses to write any data, i'm sure that SD cards can run at a much higher clock frequency, some around 50MHz but my SD cards dont work anywhere near these speeds?

I'm using the STM32SD library, the line "size_t size= file.write(sdWriteBuffer, 512);" returns 0 when the RCC_PLLQ_DIV2 is set.

-edit-
file.write() fatfs throws an abort of "FR_DISK_ERR, /* (1) A hard error occurred in the low level disk I/O layer */" dif this helps?

-edit-
i have created another post here describing the isue https://community.st.com/s/feed/0D53W00000Wa08YSAR

Posted: **Tue Feb 02, 2021 7:30 pm**

Answer: The SDMMC1 low write speeds were not due to the clock speed, it was a problem with the application software.

Posted: **Tue Feb 02, 2021 8:09 pm**

Thanks for the feedback

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