keil5STM32F103使用RS485发送接受数据代码

以下是基于Keil 5和STM32F103单片机使用RS485进行数据发送和接收的代码示例：

#include "stm32f10x.h"

#define RS485_GPIO GPIOA
#define RS485_PIN GPIO_Pin_8

USART_InitTypeDef USART_InitStructure;

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    // Configure USART1 Tx (PA.09) as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // Configure USART1 Rx (PA.10) as input floating
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // Configure USART1 RTS/CTS pins (PA.11, PA.12) as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_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_RTS_CTS;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    // Enable USART1
    USART_Cmd(USART1, ENABLE);
}

void RS485_TxEnable(void)
{
    GPIO_ResetBits(RS485_GPIO, RS485_PIN);
}

void RS485_RxEnable(void)
{
    GPIO_SetBits(RS485_GPIO, RS485_PIN);
}

void USART1_SendByte(uint8_t data)
{
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
    USART_SendData(USART1, data);
}

void USART1_SendString(const char* str)
{
    while (*str)
    {
        USART1_SendByte(*str++);
    }
}

uint8_t USART1_ReceiveByte(void)
{
    while (USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET);
    return USART_ReceiveData(USART1);
}

int main(void)
{
    uint8_t txBuffer[10] = {0xAA, 0x55, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
    uint8_t rxBuffer[10];
    uint8_t i;

    USART1_Init();

    // Configure GPIO for RS485 control
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = RS485_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(RS485_GPIO, &GPIO_InitStructure);

    while (1)
    {
        // Transmit data
        RS485_TxEnable();
        for (i = 0; i < sizeof(txBuffer); i++)
        {
            USART1_SendByte(txBuffer[i]);
        }
        RS485_RxEnable();

        // Receive data
        for (i = 0; i < sizeof(rxBuffer); i++)
        {
            rxBuffer[i] = USART1_ReceiveByte();
        }
    }
}

在这个示例中，我们使用USART1进行数据传输，并使用PA8作为RS485控制引脚。在发送数据之前，我们将RS485控制引脚拉低，表示进入发送模式。在接收数据之前，我们将RS485控制引脚拉高，表示进入接收模式。注意在发送和接收数据时，我们需要交替地切换RS485控制引脚的状态。

在您的实际应用中，您需要根据自己的需求修改代码。