linux uart 读写

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>

int open_uart(const char *port, speed_t baud_rate) {
    int fd = open(port, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror("Failed to open serial port");
        return -1;
    }

    struct termios options;
    tcgetattr(fd, &options);

    cfsetispeed(&options, baud_rate);
    cfsetospeed(&options, baud_rate);

    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    options.c_oflag &= ~OPOST;

    tcsetattr(fd, TCSANOW, &options);

    return fd;
}

void write_uart(int fd, const char *data, size_t length) {
    ssize_t bytes_written = write(fd, data, length);
    if (bytes_written == -1) {
        perror("Failed to write to serial port");
    } else {
        printf("Wrote %zd bytes to serial port\n", bytes_written);
    }
}

void read_uart(int fd, char *buffer, size_t length) {
    ssize_t bytes_read = read(fd, buffer, length);
    if (bytes_read == -1) {
        perror("Failed to read from serial port");
    } else {
        buffer[bytes_read] = '\0';
        printf("Read %zd bytes from serial port: %s\n", bytes_read, buffer);
    }
}

int main() {
    int fd = open_uart("/dev/ttyS0", B9600);
    if (fd == -1) {
        return 1;
    }

    const char *message = "Hello, UART!";
    write_uart(fd, message, strlen(message));

    char buffer[256];
    read_uart(fd, buffer, sizeof(buffer));

    close(fd);
    return 0;
}