这篇测试下串口printf输出。

一、串口硬件部分

1.1、MCU串口端口

1.2、串口连接到仿真器

二、代码

使用cubemx软件配置时钟和串口代码

2.1、配置时钟

stm32c031芯片的外接时钟晶振是48MHz，配置时钟选择外部

生成的代码

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

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  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_HSE;
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    Error_Handler();
  }
}

2.2、配置串口

在生成的代码上进行修改

void init_usart(uint32_t baudrate)
{
     GPIO_InitTypeDef GPIO_InitStruct = {0};

    __HAL_RCC_USART2_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**USART2 GPIO Configuration
    PA2     ------> USART2_TX
    PA3     ------> USART2_RX
    */
    GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_3;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF1_USART2;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    g_usart2.Instance = USART2;
  g_usart2.Init.BaudRate = baudrate;
  g_usart2.Init.WordLength = UART_WORDLENGTH_8B;
  g_usart2.Init.StopBits = UART_STOPBITS_1;
  g_usart2.Init.Parity = UART_PARITY_NONE;
  g_usart2.Init.Mode = UART_MODE_TX_RX;
  g_usart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  g_usart2.Init.OverSampling = UART_OVERSAMPLING_16;
  g_usart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  g_usart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  g_usart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
    HAL_UART_Init(&g_usart2);
}

2.3、添加MicoLIB

添加代码

#if defined (__ICCARM__) || defined (__ARMCC_VERSION)
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#elif defined(__GNUC__)
   /* With GCC, small printf (option LD Linker->Libraries->Small printf
   set to 'Yes') calls __io_putchar() */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#endif /* __ICCARM__ || __ARMCC_VERSION */

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(&g_usart2, (uint8_t *)&ch, 1, 0xFFFF);

  return ch;
}

2.4、main.c

#include "main.h"

void SystemClock_Config(void);

int main(void)
{
  HAL_Init();

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

    init_led();
    init_usart(115200); 

  while (1)
  {
        printf("https://shequ.stmicroelectronics.cn/stm32c031!\r\n");
    led4_tog();
    HAL_Delay(100);
  }
}

三、运行

编译后，下载程序到开发板

串口输出乱码

修改时钟频率，时钟为配置的48M。修改内容如下：

重新编译，下载后，串口输出

串口输出正常。

学到了