USART3 (on Arduino connector CN14) troubles on stm32u5 iot eval board BU585IIO2A

[PSchb.1]

i'm using the  stm32u5 iot eval board BU585IIO2A and want to use USART3 on Arduino connector CN14

i successfully got the PWM working on PIN7 of CN14 but i fail to get anything sent / received on UASRT3 (Pins 1 and 2 of CN14)

are there any hints / samples how to get this working ?

thx, peter

[Mike_ST]

>> we must still have some differences in our project settings - how could we find them ?

I have sent you my main.c file. Can't do more.

Just check that your stm32u5xx_hal_msp.c file assigns the USART3 to PD8/PD9 instead of default PC10/PC11.

Share your project if you feel like.

[PSchb.1]

i checked that anc actually it does NOT.

see the code below :

void HAL_UART_MspInit(UART_HandleTypeDef* huart)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
  if(huart->Instance==USART1)
  {
  /* USER CODE BEGIN USART1_MspInit 0 */
 
  /* USER CODE END USART1_MspInit 0 */
 
  /** Initializes the peripherals clock
  */
    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1;
    PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK2;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
    {
      Error_Handler();
    }
 
    /* Peripheral clock enable */
    __HAL_RCC_USART1_CLK_ENABLE();
 
    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**USART1 GPIO Configuration
    PA10     ------> USART1_RX
    PA9     ------> USART1_TX
    */
    GPIO_InitStruct.Pin = T_VCP_RX_Pin|T_VCP_TX_Pin;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
    /* USART1 interrupt Init */
    HAL_NVIC_SetPriority(USART1_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(USART1_IRQn);
  /* USER CODE BEGIN USART1_MspInit 1 */
 
  /* USER CODE END USART1_MspInit 1 */
  }
  else if(huart->Instance==USART3)
  {
  /* USER CODE BEGIN USART3_MspInit 0 */
 
  /* USER CODE END USART3_MspInit 0 */
 
  /** Initializes the peripherals clock
  */
    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART3;
    PeriphClkInit.Usart3ClockSelection = RCC_USART3CLKSOURCE_PCLK1;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
    {
      Error_Handler();
    }
 
    /* Peripheral clock enable */
    __HAL_RCC_USART3_CLK_ENABLE();
 
    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**USART3 GPIO Configuration
    PA7     ------> USART3_TX
    PA5     ------> USART3_RX
    */
    GPIO_InitStruct.Pin = GPIO_PIN_7|GPIO_PIN_5;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    GPIO_InitStruct.Alternate = GPIO_AF7_USART3;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
    /* USART3 interrupt Init */
    HAL_NVIC_SetPriority(USART3_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(USART3_IRQn);
  /* USER CODE BEGIN USART3_MspInit 1 */
 
  /* USER CODE END USART3_MspInit 1 */
  }
 
}

do you think, that's the problem ?

do i have to set up this specifically in the .ioc file ?

thx again, mike - i think now we are on the right track ... 😉

[Mike_ST · Accepted solution]

Yes, that should be the problem...

In the .ioc you have to assign it to PD8/PD9,

and you should end up with that:

   /* Peripheral clock enable */

   __HAL_RCC_USART3_CLK_ENABLE();

   __HAL_RCC_GPIOD_CLK_ENABLE();

   /**USART3 GPIO Configuration

   PD8    ------> USART3_TX

   PD9    ------> USART3_RX

   */

   GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;

   GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

   GPIO_InitStruct.Pull = GPIO_NOPULL;

   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

   GPIO_InitStruct.Alternate = GPIO_AF7_USART3;

   HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

/* USART3 interrupt Init */

HAL_NVIC_SetPriority(USART3_IRQn, 0, 0);

HAL_NVIC_EnableIRQ(USART3_IRQn);

[PSchb.1]

i checked and fixed that : (sorry, i was not aware of the necessary re-assignment :( )

anyway, you've made my day !

with that adaption now your main.c work, as well so i think, it's also going to work with my application, now

thx, again, mike : great support !

peter