单片机全双工串行通信代码

以下是一个基于8051单片机的全双工串行通信代码示例：

#include <reg52.h>

#define BAUDRATE 9600
#define FOSC 11059200L
#define TIMER_PRESCALER 12

sbit TXD = P3^1;
sbit RXD = P3^0;

void init_serial() {
    TMOD &= 0x0F;
    TMOD |= 0x20; //Timer 1, Mode 2 (8-bit auto-reload)
    TH1 = 256 - (FOSC/(TIMER_PRESCALER*BAUDRATE*32)); //Set the baud rate
    TR1 = 1; //Start Timer 1
    SCON = 0x50; //8-bit data, 1 stop bit, receive enabled
}

void send_byte(unsigned char byte) {
    SBUF = byte; //Load byte to the serial buffer
    while(TI == 0); //Wait for transmit interrupt flag to set
    TI = 0; //Clear transmit interrupt flag
}

unsigned char receive_byte() {
    while(RI == 0); //Wait for receive interrupt flag to set
    RI = 0; //Clear receive interrupt flag
    return SBUF; //Return the received byte
}

void main() {
    init_serial(); //Initialize serial communication

    while(1) {
        //Echo received bytes back to the sender
        unsigned char received_byte = receive_byte();
        send_byte(received_byte);
    }
}

这个代码实现了一个简单的回显程序，它会将接收到的每个字节原封不动地发送回去。如果你想要实现其他功能，只需要在 `main()` 函数中添加相应的代码即可。注意，这个代码示例中使用的是定时器1来生成波特率，你需要根据你的单片机类型和外部晶振频率来调整相应的参数。