STM32N6 getting stuck in USB_CoreReset( )

[johndoeEngg]

I urgently need to get USB High Speed working on USB1 of the STM32N6570-DK. I have attached the .ioc file I am using.

I am able to get the GPIO_IOToggle project working on the board. I am able to put breakpoints step through the code.

I am using  STM32CubeIDE version 1.18.0 (Build: 24413_20250227_1633 (UTC)).

As a second step, I need ThreadX working on the board.

[FBL · Accepted solution]

Hi @johndoeEngg 

The issue occurs when the function releases a timeout while waiting for the USB Core Soft Reset to finish. This timeout happens when the bit CSRST is set in the OTG_GRSTCTL register.

The root cause could be related to the PHY not being properly initialized. After enabling PHY's clock, the sequence should be followed by a delay of 10 cycles before writing core soft reset. This delay is necessary to ensure proper synchronization before resetting USB controller.

    /** Initializes the peripherals clock */
    RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USBOTGHS1;
    PeriphClkInitStruct.UsbOtgHs1ClockSelection = RCC_USBPHY1REFCLKSOURCE_HSE_DIRECT;

    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
    {
      /* Initialization Error */
      Error_Handler();
    }

    /** Set USB OTG HS PHY1 Reference Clock Source */
    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USBPHY1;
    PeriphClkInitStruct.UsbPhy1ClockSelection = RCC_USBPHY1REFCLKSOURCE_HSE_DIRECT;

    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
    {
      /* Initialization Error */
      Error_Handler();
    }

    __HAL_RCC_GPIOA_CLK_ENABLE();

    LL_AHB5_GRP1_ForceReset(0x00800000);
    __HAL_RCC_USB1_OTG_HS_FORCE_RESET();
    __HAL_RCC_USB1_OTG_HS_PHY_FORCE_RESET();

    LL_RCC_HSE_SelectHSEDiv2AsDiv2Clock();
    LL_AHB5_GRP1_ReleaseReset(0x00800000);

    /* Peripheral clock enable */
    __HAL_RCC_USB1_OTG_HS_CLK_ENABLE();

    /* Required few clock cycles before accessing USB PHY Controller Registers */
    HAL_Delay(1);

    USB1_HS_PHYC->USBPHYC_CR &= ~(0x7 << 0x4);
    /*Set the PHY reference clock speed to 24 MHz */
    USB1_HS_PHYC->USBPHYC_CR |= (0x1 << 16) |
                                (0x2 << 4)  |
                                (0x1 << 2)  |
                                 0x1U;

    __HAL_RCC_USB1_OTG_HS_PHY_RELEASE_RESET();

    /* Required few clock cycles before Releasing Reset */
    HAL_Delay(1);

    __HAL_RCC_USB1_OTG_HS_RELEASE_RESET();

    /* Peripheral PHY clock enable */
    __HAL_RCC_USB1_OTG_HS_PHY_CLK_ENABLE();

HAL_Delay(1) introduced here is dependent on CPU frequency and not reliable. You can insert __NOP() to ensure that the delay is consistent. The volatile keyword ensures that the loop is not optimized away by the compiler.

 /* Required few clock cycles before accessing USB PHY Controller Registers */
        for (volatile uint32_t i = 0; i < 10; i++) {
            __NOP(); // No Operation instruction to create a delay
        }

[johndoeEngg]

Hi FBL,

 Thanks a lot for your quick response. I am able to get past this stage with the code you posted.

 I went back to the configuration and enabled USBX. Does USBX work without ThreadX ?

 I am not able to get the eval board enumerated on my laptop.

 I am guessing I am missing bunch of stuff during initialization and starting the USB HS interface before hitting my simple main loop.

I am using the STM32N6570-DK which has a 48 MHz HSE. I am configuring OTGPHY1 and OTGHS1 to 24 MHz.

 I am pasting my main( ) function.

int main(void)

{

/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

/* MCU Configuration--------------------------------------------------------*/

HAL_Init();

/* USER CODE BEGIN Init */

/* USER CODE END Init */

/* Configure the system clock */

SystemClock_Config();

/* Configure the peripherals common clocks */

PeriphCommonClock_Config();

/* USER CODE BEGIN SysInit */

/* USER CODE END SysInit */

/* Initialize all configured peripherals */

MX_GPIO_Init();

MX_ADC1_Init();

MX_I2C1_Init();

MX_I2C2_Init();

MX_ICACHE_Init();

MX_MDF1_Init();

MX_USART1_UART_Init();

MX_USB1_OTG_HS_PCD_Init();

MX_USBX_Init();

/* USER CODE BEGIN 2 */

/* USER CODE END 2 */

/* Infinite loop */

/* USER CODE BEGIN WHILE */

while (1)

{

/* USER CODE END WHILE */

HAL_GPIO_TogglePin(LED1_GPIO_Port, LED1_Pin);

/* Insert delay 100 ms */

HAL_Delay(100);

/* USER CODE BEGIN 3 */

}

/* USER CODE END 3 */

}

Here's my modified HAL_PCD_MspInit( ) function .

void HAL_PCD_MspInit(PCD_HandleTypeDef* hpcd)

{

if (hpcd->Instance==USB1_OTG_HS)

{

/* USER CODE BEGIN USB1_OTG_HS_MspInit 0 */

/* USER CODE END USB1_OTG_HS_MspInit 0 */

if (1)

{

/** Initializes the peripherals clock */

RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};

PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USBOTGHS1;

PeriphClkInitStruct.UsbOtgHs1ClockSelection = RCC_USBPHY1REFCLKSOURCE_OTGPHY1; // RCC_USBPHY1REFCLKSOURCE_HSE_DIRECT;

if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)

{

/* Initialization Error */

Error_Handler();

}

/** Set USB OTG HS PHY1 Reference Clock Source */

PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USBPHY1;

PeriphClkInitStruct.UsbPhy1ClockSelection = RCC_USBOTGHS1CLKSOURCE_HSE_DIV2; // RCC_USBPHY1REFCLKSOURCE_HSE_DIRECT;

if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)

{

/* Initialization Error */

Error_Handler();

}

__HAL_RCC_GPIOA_CLK_ENABLE();

LL_AHB5_GRP1_ForceReset(0x00800000);

__HAL_RCC_USB1_OTG_HS_FORCE_RESET();

__HAL_RCC_USB1_OTG_HS_PHY_FORCE_RESET();

LL_RCC_HSE_SelectHSEDiv2AsDiv2Clock();

LL_AHB5_GRP1_ReleaseReset(0x00800000);

/* Peripheral clock enable */

__HAL_RCC_USB1_OTG_HS_CLK_ENABLE();

/* Required few clock cycles before accessing USB PHY Controller Registers */

HAL_Delay(10);

USB1_HS_PHYC->USBPHYC_CR &= ~(0x7 << 0x4);

/*Set the PHY reference clock speed to 24 MHz */

USB1_HS_PHYC->USBPHYC_CR |= (0x1 << 16) |

(0x2 << 4) |

(0x1 << 2) |

0x1U;

__HAL_RCC_USB1_OTG_HS_PHY_RELEASE_RESET();

/* Required few clock cycles before Releasing Reset */

HAL_Delay(10);

__HAL_RCC_USB1_OTG_HS_RELEASE_RESET();

/* Peripheral PHY clock enable */

__HAL_RCC_USB1_OTG_HS_PHY_CLK_ENABLE();

/* USB1_OTG_HS interrupt Init */

// rkris - added this code

HAL_NVIC_SetPriority(USB1_OTG_HS_IRQn, 0, 0);

HAL_NVIC_EnableIRQ(USB1_OTG_HS_IRQn);

}

/* USER CODE BEGIN USB1_OTG_HS_MspInit 1 */

/* USER CODE END USB1_OTG_HS_MspInit 1 */

}

}

I have attached the updated "ioc" file.

Thanks

JD

[FBL]

Hi @johndoeEngg 

So far, no examples provided covering USBX standalone on STM32N6. Some examples provided using classic middleware.