stm32h755 Clock setup: HAL_RCC_ClockConfig returns error.

[Mark12]

Hi all,

I am having issues with Clock setup for Stm32h755. Especially regarding the M4 core. Currently, I only run the M4 core. The M7 core has no valid firmware. Is that even a supported mode?

I try to setup a rather basic clock setup but the setup keeps failing at the call: HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4), which will return an not ok return value.

I also tried using HSI and other different setups. But it seems the keep failing in the same way. Interestingly... When I simply ignore the error. Then most stuff seems to work just fine. I got ADC, SPI, Timers working. However, I am not sure where the issue is with the clock configuration.

The entire clock setup: 

static void SystemClock_Config(void) {
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

    __HAL_RCC_SYSCFG_CLK_ENABLE();

    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_HSE;
    RCC_OscInitStruct.HSEState       = RCC_HSE_ON;
    RCC_OscInitStruct.HSIState       = RCC_HSI_ON;
    RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource  = RCC_PLLSOURCE_HSE;
    RCC_OscInitStruct.PLL.PLLM       = 5;
    RCC_OscInitStruct.PLL.PLLN       = 192;
    RCC_OscInitStruct.PLL.PLLP       = 2;
    RCC_OscInitStruct.PLL.PLLQ       = 2;
    RCC_OscInitStruct.PLL.PLLR       = 2;
    RCC_OscInitStruct.PLL.PLLRGE     = RCC_PLL1VCIRANGE_2;
    RCC_OscInitStruct.PLL.PLLVCOSEL  = RCC_PLL1VCOWIDE;
    RCC_OscInitStruct.PLL.PLLFRACN   = 0;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        // print error
    }

    /** Initializes the CPU, AHB and APB buses clocks
     */
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1 |
                                  RCC_CLOCKTYPE_PCLK2 | RCC_CLOCKTYPE_D3PCLK1 | RCC_CLOCKTYPE_D1PCLK1;
    RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.SYSCLKDivider  = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.AHBCLKDivider  = RCC_HCLK_DIV2;
    RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
    RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4) != HAL_OK) {
        // print error
    }
}

Best regards

Mark

---

Edited to apply proper source code formatting - please see How to insert source code for future reference.

[TDK]

The clock failing to start can suggest the HSE design is not correct. Perhaps incorrect load caps.

Guidelines for oscillator design on STM8AF/AL/S and STM32 MCUs/MPUs - Application note

M4 having no firmware is fine. You can set option bytes such that the M4 core doesn't boot, but it's not an issue here.

[Andrew Neil]

---

@Mark12 wrote:

the call: HAL_RCC_ClockConfig( &RCC_ClkInitStruct, FLASH_LATENCY_4 ), which will return an not ok return value..

---

Have you tried stepping into that function to see where & why, exactly, it is failing?

[mƎALLEm]

Hello,

Which board are you using? Nucleo board?

If it's the case, you need to set HSE in Bypass mode as the clock source is provided from the STLINK (STLINK_MCO) and there is no crystal on the board: