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UART cosfiguration directly with registers, NUCLEO-H563ZI board

G-Poulios
Associate II

I am using the NUCLEO-H563ZI board and I am trying to configure the UART2 using only registers.

I started by creating a fresh and simple new code with STM32CubeIDE for UART transmit because I wanted to use a simple uart_transmit function but I had trouble making it work until I activated the USB as Host_Only from the .ioc

Pinout & Configuration and only then was I able to use the HAL_UART_Transmit to send a text to a terminal and I would like to know why that is.

 

Then I want to be able to configure the UART2 directly with the registers but then the code breaks how can I make this work? Thank you.

 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "app_usbx_host.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

UART_HandleTypeDef huart2;

HCD_HandleTypeDef hhcd_USB_DRD_FS;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ICACHE_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_USB_HCD_Init(void);
/* USER CODE BEGIN PFP */
uint8_t data[] = "HELLO WORLD \r\n";
/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
	HAL_UART_Transmit (&huart2, data, sizeof (data), 1000);
}
/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

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

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_ICACHE_Init();
  MX_USART2_UART_Init();
  MX_USB_HCD_Init();
  MX_USBX_Host_Init();
  /* USER CODE BEGIN 2 */
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */


	  HAL_UART_Transmit (&huart2, data, sizeof (data), 1000);
	  HAL_Delay (1000);

  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE0);

  while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48|RCC_OSCILLATORTYPE_CSI;
  RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
  RCC_OscInitStruct.CSIState = RCC_CSI_ON;
  RCC_OscInitStruct.CSICalibrationValue = RCC_CSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLL1_SOURCE_CSI;
  RCC_OscInitStruct.PLL.PLLM = 1;
  RCC_OscInitStruct.PLL.PLLN = 125;
  RCC_OscInitStruct.PLL.PLLP = 2;
  RCC_OscInitStruct.PLL.PLLQ = 2;
  RCC_OscInitStruct.PLL.PLLR = 2;
  RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1_VCIRANGE_2;
  RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1_VCORANGE_WIDE;
  RCC_OscInitStruct.PLL.PLLFRACN = 0;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** 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_PCLK3;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief ICACHE Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_ICACHE_Init(void)
{

  /* USER CODE BEGIN ICACHE_Init 0 */

  /* USER CODE END ICACHE_Init 0 */

  /* USER CODE BEGIN ICACHE_Init 1 */

  /* USER CODE END ICACHE_Init 1 */

  /** Enable instruction cache (default 2-ways set associative cache)
  */
  if (HAL_ICACHE_Enable() != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN ICACHE_Init 2 */

  /* USER CODE END ICACHE_Init 2 */

}

/**
  * @brief USART2 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_USART2_UART_Init(void)
{

  /* USER CODE BEGIN USART2_Init 0 */
    RCC->AHB2ENR |= RCC_AHB2ENR_GPIODEN;        // ENABLE GPIO PORT D CLOCK (BIT 0)
    RCC->APB1LENR |= RCC_APB1LENR_USART2EN;       // ENABLE UART2 CLOCK (BIT 14)

///*
    GPIOD->MODER &= ~((3u << 10)    // CLEAR PD5
                     |(3u << 12));  // CLEAR PD6

    // SET PIN MODES
    GPIOD->MODER |= ((2u << 10)     // SET PD5 TO AF
                    |(2u << 12));   // SET PD6 TO AF

    GPIOD->AFR[2] &= ~((15u << 20)       // CLEAR PD5 AF
                      |(15u << 24));     // CLEAR PD6 AF

    // SET ALTERNATE FUNCTION
    GPIOD->AFR[2] |= ((7u << 20)         // SET PD5 AF
                     |(7u << 24));       // SET PD6 AF
//*/




    USART2->CR1 &= ~(USART_CR1_M1       // CLEAR M1 FOR 1 START BIT AND 8 DATA BITS (28)
                    |(0x03 << 26)       // INHIBIT INTERRUPTS AT BITS 26 AND 27     (27/26)
                    |USART_CR1_OVER8    // OVERSAMPLING BY 16                       (15)
                    |USART_CR1_CMIE     // INHIBIT CHARACTER MATCH INTERRUPT        (14)
                    |USART_CR1_MME      // DON'T ENABLE MUTE MODE                   (13)
                    |USART_CR1_M0       // CLEAR M0 FOR 1 START BIT AND 8 DATA BITS (12)
                    |USART_CR1_PCE      // NOT IMPLEMENTING PARITY CONTROL          (10)
                    |(0x1F << 3)        // INHIBIT INTERRUPTS AT BITS 4 TO 8        (4-8)
                    |USART_CR1_TE       // DON'T ENABLE TRANSMITTER JUST YET        (3)
                    |USART_CR1_RE       // DON'T ENABLE RECEIVER JUST YET           (2)
                    |USART_CR1_UE);     // DON'T ENABLE UART2 JUST YET              (0)

    // CONFIGURE USART CR2 REGISTER
    // CLEAR BITS
    USART2->CR2 &= ~(USART_CR2_RTOEN    // DISABLE RECEIVER TIMEOUT             (23)
                    |USART_CR2_ABREN    // NO AUTOMATIC BAUD RATE DETECTION     (20)
                    |USART_CR2_MSBFIRST // TRANSMIT/RECEIVE LSB FIRST           (19)
                    |(0x03 << 16)       // IDLE STATE HIGH FOR RX/TX PINS       (17/16)
                    |USART_CR2_SWAP     // DON'T SWAP FUNCTION OF RX/TX PINS    (15)
                    |USART_CR2_LINEN    // NO LIN MODE                          (14)
                    |(0x03 << 12)       // 1 STOP BIT                           (13/12)
                    |USART_CR2_CLKEN    // DON'T USE CLOCK WITH UART            (11)
                    |USART_CR2_LBDIE);  // NO LIN BREAK DETECTION INTERRUPT     (6)

    // CONFIGURE USART CR3 REGISTER
    // CLEAR BITS
    USART2->CR3 &= ~(USART_CR3_TCBGTIE  // NO TRANSMISSION COMPLETE BEFORE GUART TIME INTERRUPT (24)
                    |USART_CR3_DEM      // NO DRIVER ENABLE MODE                                (14)
                    |(0x7F << 3)        // DISABLE VARIOUS IRRELEVANT MODES                     (9-3)
                    |USART_CR3_IREN     // NO IrDA MODE                                         (1)
                    |USART_CR3_EIE);    // INHIBIT ERROR INTERRUPT                              (0)

    // SET BITS
    USART2->CR3 |= (USART_CR3_OVRDIS    // DISABLE OVERRUN FUNCTIONALITY (12)
                   |USART_CR3_ONEBIT);  // USE ONE SAMPLE BIT METHOD     (11)

    // SET BAUD RATE IN BRR REGISTER
    USART2->BRR = 2170;
    // VALUE THAT SETS BAUD RATE TO 115,200 AT INPUT FREQUENCY OF 4MHZ

    // ENABLE UART
    USART2->CR1 |= (USART_CR1_TE        // ENABLE TRANSMITTER (3)
                   |USART_CR1_RE        // ENABLE RECEIVER    (2)
                   |USART_CR1_UE);      // ENABLE UART2       (0)



    /*
	USART2->CR1 = 0x00;   // Clear ALL
	USART2->CR1 |= (1<<13);   // UE = 1... Enable USART
	USART2->BRR = 2170;   // Baud rate of 115200, PCLK1 at 45MHz

	USART2->CR1 |= (1<<2); // RE=1.. Enable the Receiver
	USART2->CR1 |= (1<<3);
    */
  /* USER CODE END USART2_Init 0 */

  /* USER CODE BEGIN USART2_Init 1 */

  /* USER CODE END USART2_Init 1 */

	/*
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  */
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart2, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart2, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart2) != HAL_OK)
  {
    Error_Handler();
  }


  /* USER CODE BEGIN USART2_Init 2 */

  /* USER CODE END USART2_Init 2 */

}

/**
  * @brief USB Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_USB_HCD_Init(void)
{

  /* USER CODE BEGIN USB_Init 0 */

  /* USER CODE END USB_Init 0 */

  /* USER CODE BEGIN USB_Init 1 */

  /* USER CODE END USB_Init 1 */
  hhcd_USB_DRD_FS.Instance = USB_DRD_FS;
  hhcd_USB_DRD_FS.Init.dev_endpoints = 8;
  hhcd_USB_DRD_FS.Init.Host_channels = 8;
  hhcd_USB_DRD_FS.Init.speed = USBD_FS_SPEED;
  hhcd_USB_DRD_FS.Init.phy_itface = HCD_PHY_EMBEDDED;
  hhcd_USB_DRD_FS.Init.Sof_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.low_power_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.vbus_sensing_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.bulk_doublebuffer_enable = DISABLE;
  hhcd_USB_DRD_FS.Init.iso_singlebuffer_enable = DISABLE;
  if (HAL_HCD_Init(&hhcd_USB_DRD_FS) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USB_Init 2 */

  /* USER CODE END USB_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOH_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

 

 

5 REPLIES 5
gbm
Lead III

There is no AFR[2] register. The bits you want to set are in AFR[0].

 

Don't do logic operations on USART CRx registers. Simply write the proper values to them. For basic setup. you only need to set BRR and CR1 - two assignments are enough.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice

Thank you but it still doesn't work

 

static void MX_USART2_UART_Init(void)
{

  /* USER CODE BEGIN USART2_Init 0 */

    RCC->AHB2ENR |= RCC_AHB2ENR_GPIODEN;        // ENABLE GPIO PORT D CLOCK (BIT 0)
    RCC->APB1LENR |= RCC_APB1LENR_USART2EN;       // ENABLE UART2 CLOCK (BIT 14)

///*
    GPIOD->MODER &= ~((3u << 10)    // CLEAR PD5
                     |(3u << 12));  // CLEAR PD6

    // SET PIN MODES
    GPIOD->MODER |= ((2u << 10)     // SET PD5 TO AF
                    |(2u << 12));   // SET PD6 TO AF

    GPIOD->AFR[0] &= ~((15u << 20)       // CLEAR PD5 AF
                      |(15u << 24));     // CLEAR PD6 AF

    // SET ALTERNATE FUNCTION
    GPIOD->AFR[0] |= ((7u << 20)         // SET PD5 AF
                     |(7u << 24));       // SET PD6 AF






    USART2->CR1 &= ~(USART_CR1_M1       // CLEAR M1 FOR 1 START BIT AND 8 DATA BITS (28)
                    |(0x03 << 26)       // INHIBIT INTERRUPTS AT BITS 26 AND 27    (27/26)
                    |USART_CR1_OVER8    // OVERSAMPLING BY 16                       (15)
                    |USART_CR1_CMIE     // INHIBIT CHARACTER MATCH INTERRUPT        (14)
                    |USART_CR1_MME      // DON'T ENABLE MUTE MODE                   (13)
                    |USART_CR1_M0       // CLEAR M0 FOR 1 START BIT AND 8 DATA BITS (12)
                    |USART_CR1_PCE      // NOT IMPLEMENTING PARITY CONTROL          (10)
                    |(0x1F << 3)        // INHIBIT INTERRUPTS AT BITS 4 TO 8        (4-8)
                    |USART_CR1_TE       // DON'T ENABLE TRANSMITTER JUST YET        (3)
                    |USART_CR1_RE       // DON'T ENABLE RECEIVER JUST YET           (2)
                    |USART_CR1_UE);     // DON'T ENABLE UART2 JUST YET              (0)

    // SET BAUD RATE IN BRR REGISTER
    USART2->BRR = 2170;

    // VALUE THAT SETS BAUD RATE TO 115,200 AT INPUT FREQUENCY OF 250MHZ

    // ENABLE UART
    USART2->CR1 |= (USART_CR1_TE        // ENABLE TRANSMITTER (3)
                   |USART_CR1_RE        // ENABLE RECEIVER    (2)
                   |USART_CR1_UE);      // ENABLE UART2       (0)



  /* USER CODE END USART2_Init 0 */

  /* USER CODE BEGIN USART2_Init 1 */

  /* USER CODE END USART2_Init 1 */
  */
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart2, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart2, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART2_Init 2 */

  /* USER CODE END USART2_Init 2 */

}

 

also I see the clock config for the UART2 and it's 250MHz from the PCLK1, should I change that?

GPoulios_0-1712908160197.png

 

 

> it still doesn't work

What does this mean? What are the symptoms and how are they different from the expectations?

You still don't directly write values to the UART registers, as @gbm said above.

You are calling HAL_UART_Init() and other HAL stuff. Don't you think that overrides the registers you've just written?

Read out and check/post content of UART and relevant GPIO registers.

JW

 

The expectation is the

HAL_UART_Transmit (&huart2, data, sizeof (data), 1000);

 to transmit/write to a terminal 

HAL_UART_Transmit (&huart2, data, sizeof (data), 1000);

And as for the HAL overwriting the changes, well that's what I am asking, how can I deviate from the HAL libraries and start using exclusively the the registers(that's the end goal), but for now I am trying to do it bit by bit to debug cause I haven't found almost any examples for stm32h563zi specifically or any that I could make them work for my application.

Cube/HAL is open source, you can have a look what does it do. Alternatively, just don't use it at all.

Observe UART and GPIO registers content.

Observe the UART Tx pin using oscilloscope/logic analyzer.

JW