STM32串口1发送指令，将串口1接收的数据通过串口2发送出去

以下是一个基本的示例代码，演示如何使用STM32的串口1和串口2将接收到的数据转发到另一个串口。

首先，需要在代码中包含必要的库头文件：

#include "stm32f4xx.h"
#include "stm32f4xx_usart.h"
#include "stm32f4xx_gpio.h"

然后，需要定义一些常量和变量，这里我们将串口1和串口2的波特率都设置为115200：

#define USART1_BAUDRATE 115200
#define USART2_BAUDRATE 115200

char received_char; // 用于存储接收到的字符

接下来，需要初始化串口1和串口2。这里我们使用的是STM32F4系列的芯片，因此需要使用HAL库来初始化串口。具体的初始化代码如下所示：

/* 串口1初始化 */
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;

/* 使能GPIOA的时钟 */
__HAL_RCC_GPIOA_CLK_ENABLE();

/* 使能USART1的时钟 */
__HAL_RCC_USART1_CLK_ENABLE();

/* 配置PA9（USART1_TX）为复用功能 */
GPIO_InitStruct.Pin = GPIO_PIN_9;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* 配置PA10（USART1_RX）为复用功能 */
GPIO_InitStruct.Pin = GPIO_PIN_10;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* 配置USART1的参数 */
USART_InitStruct.BaudRate = USART1_BAUDRATE;
USART_InitStruct.WordLength = USART_WORDLENGTH_8B;
USART_InitStruct.StopBits = USART_STOPBITS_1;
USART_InitStruct.Parity = USART_PARITY_NONE;
USART_InitStruct.Mode = USART_MODE_TX_RX;
USART_InitStruct.HwFlowCtl = USART_HWCONTROL_NONE;
USART_InitStruct.OverSampling = USART_OVERSAMPLING_16;
HAL_USART_Init(&huart1, &USART_InitStruct);

/* 串口2初始化 */
GPIO_InitStruct.Pin = GPIO_PIN_2 | GPIO_PIN_3;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

__HAL_RCC_USART2_CLK_ENABLE();

USART_InitStruct.BaudRate = USART2_BAUDRATE;
USART_InitStruct.WordLength = USART_WORDLENGTH_8B;
USART_InitStruct.StopBits = USART_STOPBITS_1;
USART_InitStruct.Parity = USART_PARITY_NONE;
USART_InitStruct.Mode = USART_MODE_TX_RX;
USART_InitStruct.HwFlowCtl = USART_HWCONTROL_NONE;
USART_InitStruct.OverSampling = USART_OVERSAMPLING_16;
HAL_USART_Init(&huart2, &USART_InitStruct);

接下来是主循环。在主循环中，我们首先检查串口1是否接收到了数据。如果接收到了数据，则将数据发送到串口2。代码如下：

while (1) {
  /* 检查串口1是否接收到了数据 */
  if (__HAL_USART_GET_FLAG(&huart1, USART_FLAG_RXNE) != RESET) {
    /* 读取接收到的数据 */
    received_char = (char)(huart1.Instance->DR & (uint8_t)0xFF);

    /* 将数据发送到串口2 */
    while (__HAL_USART_GET_FLAG(&huart2, USART_FLAG_TXE) == RESET);
    huart2.Instance->DR = (uint8_t)received_char;
  }
}

最后，需要在main函数中调用HAL库的启动函数来启动系统：

int main(void) {
  /* 初始化HAL库 */
  HAL_Init();

  /* 初始化串口1和串口2 */
  USART1_UART_Init();
  USART2_UART_Init();

  /* 启动系统 */
  HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(SysTick_IRQn);
  HAL_USART_MspInit(&huart1);
  HAL_USART_MspInit(&huart2);

  /* 进入主循环 */
  main_loop();
}

完整的代码如下所示：

#include "stm32f4xx.h"
#include "stm32f4xx_usart.h"
#include "stm32f4xx_gpio.h"

#define USART1_BAUDRATE 115200
#define USART2_BAUDRATE 115200

char received_char;

void USART1_UART_Init(void) {
  GPIO_InitTypeDef GPIO_InitStruct;
  USART_InitTypeDef USART_InitStruct;

  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_USART1_CLK_ENABLE();

  GPIO_InitStruct.Pin = GPIO_PIN_9;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = GPIO_PIN_10;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  USART_InitStruct.BaudRate = USART1_BAUDRATE;
  USART_InitStruct.WordLength = USART_WORDLENGTH_8B;
  USART_InitStruct.StopBits = USART_STOPBITS_1;
  USART_InitStruct.Parity = USART_PARITY_NONE;
  USART_InitStruct.Mode = USART_MODE_TX_RX;
  USART_InitStruct.HwFlowCtl = USART_HWCONTROL_NONE;
  USART_InitStruct.OverSampling = USART_OVERSAMPLING_16;
  HAL_USART_Init(&huart1, &USART_InitStruct);
}

void USART2_UART_Init(void) {
  GPIO_InitTypeDef GPIO_InitStruct;
  USART_InitTypeDef USART_InitStruct;

  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_USART2_CLK_ENABLE();

  GPIO_InitStruct.Pin = GPIO_PIN_2 | GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  USART_InitStruct.BaudRate = USART2_BAUDRATE;
  USART_InitStruct.WordLength = USART_WORDLENGTH_8B;
  USART_InitStruct.StopBits = USART_STOPBITS_1;
  USART_InitStruct.Parity = USART_PARITY_NONE;
  USART_InitStruct.Mode = USART_MODE_TX_RX;
  USART_InitStruct.HwFlowCtl = USART_HWCONTROL_NONE;
  USART_InitStruct.OverSampling = USART_OVERSAMPLING_16;
  HAL_USART_Init(&huart2, &USART_InitStruct);
}

void main_loop(void) {
  while (1) {
    if (__HAL_USART_GET_FLAG(&huart1, USART_FLAG_RXNE) != RESET) {
      received_char = (char)(huart1.Instance->DR & (uint8_t)0xFF);
      while (__HAL_USART_GET_FLAG(&huart2, USART_FLAG_TXE) == RESET);
      huart2.Instance->DR = (uint8_t)received_char;
    }
  }
}

int main(void) {
  HAL_Init();

  USART1_UART_Init();
  USART2_UART_Init();

  HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(SysTick_IRQn);
  HAL_USART_MspInit(&huart1);
  HAL_USART_MspInit(&huart2);

  main_loop();
}

请注意，此示例代码仅演示了如何通过串口1和串口2将接收到的数据转发到另一个串口。在实际应用中，您需要根据自己的需求进行修改和优化。