keil5rs485发送接收数据

在Keil uVision5中，可以使用串口通信方式来实现RS485的发送和接收数据。下面是一个基本的RS485发送和接收数据的代码示例：

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

#define USART1_TX_GPIO        GPIO_Pin_9
#define USART1_RX_GPIO        GPIO_Pin_10

#define RS485_DIR_GPIO        GPIO_Pin_11
#define RS485_DIR_HIGH()      GPIO_SetBits(GPIOA, RS485_DIR_GPIO)
#define RS485_DIR_LOW()       GPIO_ResetBits(GPIOA, RS485_DIR_GPIO)

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = USART1_TX_GPIO;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = USART1_RX_GPIO;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    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_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART1_SendChar(uint8_t ch)
{
    USART_SendData(USART1, ch);
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
}

uint8_t USART1_ReceiveChar(void)
{
    while (USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET);
    return USART_ReceiveData(USART1);
}

void RS485_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = RS485_DIR_GPIO;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    RS485_DIR_HIGH();
}

void RS485_SendData(uint8_t *data, uint8_t len)
{
    RS485_DIR_HIGH();
    USART1_SendChar(0x55);      // 发送起始符
    RS485_DIR_LOW();

    for (uint8_t i = 0; i < len; i++)
    {
        USART1_SendChar(data[i]);
    }

    RS485_DIR_HIGH();
    USART1_SendChar(0xAA);      // 发送结束符
}

void RS485_ReceiveData(uint8_t *data, uint8_t *len)
{
    uint8_t ch;
    *len = 0;

    RS485_DIR_LOW();
    while (1)
    {
        ch = USART1_ReceiveChar();
        if (ch == 0x55)         // 收到起始符
        {
            *len = 0;
            data[*len] = ch;
            (*len)++;
        }
        else if (ch == 0xAA)    // 收到结束符
        {
            data[*len] = ch;
            (*len)++;
            break;
        }
        else                    // 收到数据
        {
            data[*len] = ch;
            (*len)++;
        }
    }

    RS485_DIR_HIGH();
}

在这个示例中，我们使用的是USART1串口，并且将其配置为RS485模式。在发送数据时，我们先将RS485_DIR引脚置为高电平，然后发送起始符0x55，接着发送数据，最后发送结束符0xAA，发送完成后再将RS485_DIR引脚置为高电平。

在接收数据时，我们使用了一个while循环，不断接收串口数据。当收到起始符0x55时，开始接收数据，直到收到结束符0xAA时结束。在接收数据时，我们需要将RS485_DIR引脚置为低电平，以使RS485芯片处于接收状态。