关于usart2_printf的相关修正

波特率 (Baud Rate): 指串口每秒传输的位数 (bits per second, bps)。通信双方必须使用相同的波特率才能正确解码数据。

USART 时钟 (f_CK): 输入到 USART 外设的时钟频率。根据我们之前的分析，你的 USART2 时钟 (PCLK) 是 12 MHz (12,000,000 Hz)。

波特率寄存器 (USART_BRR): STM32 内部有一个寄存器，你需要写入一个特定的值 (USARTDIV)，这个值是根据 f_CK 和目标波特率计算出来的，用于分频 f_CK 以产生实际的位时钟。

过采样 (Oversampling): USART 可以配置为过采样 16 次 (OVER8=0) 或 8 次 (OVER8=1)。这会影响波特率计算公式和精度。通常推荐使用过采样 16 次，除非需要非常高的波特率或有特殊功耗要求。

计算方法 :

计算写入 BRR 寄存器的值 (USARTDIV) 的基本公式：

过采样 16 次 (OVER8 = 0):

USARTDIV = f_CK / Desired_BaudRate

过采样 8 次 (OVER8 = 1):

USARTDIV = (2 * f_CK) / Desired_BaudRate

/* USER CODE BEGIN Header */

/**

  ******************************************************************************

  * [url=home.php?mod=space&uid=288409]@file[/url]    UART/UART_Printf/Src/main.c

  * [url=home.php?mod=space&uid=187600]@author[/url]  MCD Application Team

  * [url=home.php?mod=space&uid=247401]@brief[/url]   This example shows how to retarget the C library printf function

  *          to the UART.

  ******************************************************************************

  * @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"



/* 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;



/* USER CODE BEGIN PV */

/* USER CODE END PV */



/* Private function prototypes -----------------------------------------------*/

void SystemClock_Config(void);

static void MX_GPIO_Init(void);

static void MX_USART2_UART_Init(void);

/* USER CODE BEGIN PFP */

#if defined(__ICCARM__)

__ATTRIBUTES size_t __write(int, const unsigned char *, size_t);

#endif /* __ICCARM__ */



#if defined(__ICCARM__)

/* New definition from EWARM V9, compatible with EWARM8 */

int iar_fputc(int ch);

#define PUTCHAR_PROTOTYPE int iar_fputc(int ch)

#elif defined ( __CC_ARM ) || defined(__ARMCC_VERSION)

/* ARM Compiler 5/6*/

#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)

#elif defined(__GNUC__)

#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)

#endif /* __ICCARM__ */

/* USER CODE END PFP */



/* Private user code ---------------------------------------------------------*/

/* USER CODE BEGIN 0 */



/* USER CODE END 0 */



/**

  * [url=home.php?mod=space&uid=247401]@brief[/url]  The application entry point.

  * @retval int

  */

int main(void)

{



  /* USER CODE BEGIN 1 */



  /* STM32C0xx HAL library initialization:

       - Configure the Flash prefetch

       - Systick timer is configured by default as source of time base, but user 

         can eventually implement his proper time base source (a general purpose 

         timer for example or other time source), keeping in mind that Time base 

         duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and 

         handled in milliseconds basis.

       - Low Level Initialization

     */

  /* 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 */

  /* Initialize BSP Led for LED2 */

  BSP_LED_Init(LED2);

  /* USER CODE END SysInit */



  /* Initialize all configured peripherals */

  MX_GPIO_Init();

  MX_USART2_UART_Init();

  /* USER CODE BEGIN 2 */



  /* Output a message on Hyperterminal using printf function */

  printf("\n\r UART Printf Example: retarget the C library printf function to the UART\n\r");

  printf("** Test finished successfully. ** \n\r");

  /* USER CODE END 2 */



  /* Infinite loop */

  /* USER CODE BEGIN WHILE */

  while (1)

  {

                printf("** Test finished successfully. ** \n\r");

                uint8_t test[] = {0x55, 0xAA, 'A', 'B', 'C'};  // 十六进制+ASCII混合数据

                HAL_UART_Transmit(&huart2, test, sizeof(test), 100);

    /* USER CODE END WHILE */



    /* USER CODE BEGIN 3 */



  }

  /* USER CODE END 3 */

}



/**

  * [url=home.php?mod=space&uid=247401]@brief[/url] System Clock Configuration

  * @retval None

  */

void SystemClock_Config(void)

{

  RCC_OscInitTypeDef RCC_OscInitStruct = {0};

  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};



  __HAL_FLASH_SET_LATENCY(FLASH_LATENCY_0);



  /** Initializes the RCC Oscillators according to the specified parameters

  * in the RCC_OscInitTypeDef structure.

  */

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;

  RCC_OscInitStruct.HSIState = RCC_HSI_ON;

  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV4;

  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;

  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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;

  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV4;

  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;

  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;



  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)

  {

    Error_Handler();

  }

}



/**

  * [url=home.php?mod=space&uid=247401]@brief[/url] USART2 Initialization Function

  * @param None

  * @retval None

  */

static void MX_USART2_UART_Init(void)

{



  /* USER CODE BEGIN USART2_Init 0 */



  /* USER CODE END USART2_Init 0 */



  /* USER CODE BEGIN USART2_Init 1 */



  /* USER CODE END USART2_Init 1 */

  huart2.Instance = USART2;

  huart2.Init.BaudRate = 9600;

  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();

  }

  /* USER CODE BEGIN USART2_Init 2 */



  /* USER CODE END USART2_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_GPIOF_CLK_ENABLE();

  __HAL_RCC_GPIOA_CLK_ENABLE();



  /* USER CODE BEGIN MX_GPIO_Init_2 */

  /* USER CODE END MX_GPIO_Init_2 */

}



/* USER CODE BEGIN 4 */

/**

  * @brief  Retargets the C library printf function to the USART.

  * @param  None

  * @retval None

  */

PUTCHAR_PROTOTYPE

{

  /* Place your implementation of fputc here */

  /* e.g. write a character to the USART2 and Loop until the end of transmission */

  HAL_UART_Transmit(&huart2, (uint8_t *)&ch, 1, 0xFFFF);



  return ch;

}



#if defined(__ICCARM__)

size_t __write(int file, unsigned char const *ptr, size_t len)

{

  size_t idx;

  unsigned char const *pdata = ptr;



  for (idx = 0; idx < len; idx++)

  {

    iar_fputc((int)*pdata);

    pdata++;

  }

  return len;

}

#endif /* __ICCARM__ */







void HAL_UART_ErrorCallback(UART_HandleTypeDef *huart) {

    if(huart->Instance == USART4) {

        printf("UART Error: 0x%lX\n", huart->ErrorCode);

    }

}



/* 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 */

  /* Turn LED2 on */

  BSP_LED_On(LED2);

  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) */



  /* Infinite loop */

  while (1)

  {

  }

  /* USER CODE END 6 */

}

#endif /* USE_FULL_ASSERT */