stm32f103c8t6串口2代码

下面是STM32F103C8T6串口2的代码示例，包含发送和接收功能：

#include "stm32f10x.h"
#include <stdio.h>
#include <string.h>

#define USART2_DR_BASE       0x40004404
#define USART2_SR_TC_BIT     6
#define USART2_SR_RXNE_BIT   5

void USART2_Init(void)
{
    // Enable GPIOA and USART2 clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO | RCC_APB2Periph_USART1, ENABLE);

    // Configure PA2 as TX and PA3 as RX
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // Configure USART2
    USART_InitTypeDef USART_InitStructure;
    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
    USART_Init(USART2, &USART_InitStructure);

    // Enable USART2
    USART_Cmd(USART2, ENABLE);
}

void USART2_SendChar(char c)
{
    // Wait for the transmit data register to be empty
    while ((USART2->SR & (1 << USART2_SR_TC_BIT)) == 0);

    // Send the character
    USART2->DR = (c & 0xFF);
}

void USART2_SendString(const char* str)
{
    const char* p = str;
    while (*p) {
        USART2_SendChar(*p++);
    }
}

char USART2_ReceiveChar(void)
{
    // Wait for the receive data register to be non-empty
    while ((USART2->SR & (1 << USART2_SR_RXNE_BIT)) == 0);

    // Read the character
    return USART2->DR & 0xFF;
}

int main(void)
{
    // Initialize USART2
    USART2_Init();

    // Send a string
    USART2_SendString("Hello, world!\r\n");

    // Receive a character and send it back
    while (1) {
        char c = USART2_ReceiveChar();
        USART2_SendChar(c);
    }
}

此代码使用 PA2 和 PA3 作为 USART2 的 TX 和 RX 引脚，波特率为 9600。USART2_SendChar 函数用于发送单个字符，USART2_SendString 函数用于发送字符串。USART2_ReceiveChar 函数用于接收单个字符。在主函数中，发送一个字符串后，进入一个死循环，不断接收一个字符并发送回去。