如何在C语言中读/写串口数据，打开函数的问题

Question

  fd = open("/dev/tty.usbserial-AH02OC4V", O_RDWR | O_NOCTTY);
  printf("fd opened as %i\n", fd);
  printf("Serial Open Passed!\n");

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <sys/ioctl.h>

#define DEBUG 1

int main(int argc, char *argv[])
{
  printf("start\n");
  int fd, n, i;
  char buf[64] = "temp text";
  struct termios toptions;
  printf("start\n");
  /* open serial port */
  fd = open("/dev/tty.usbserial-AH02OC4V", O_RDWR | O_NOCTTY);
  printf("fd opened as %i\n", fd);
  printf("Serial Open Passed!\n");
  /* wait for the Arduino to reboot */
  usleep(3500000);

  /* get current serial port settings */
  tcgetattr(fd, &toptions);
  /* set 9600 baud both ways */
  cfsetispeed(&toptions, B9600);
  cfsetospeed(&toptions, B9600);
  /* 8 bits, no parity, no stop bits */
  toptions.c_cflag &= ~PARENB;
  toptions.c_cflag &= ~CSTOPB;
  toptions.c_cflag &= ~CSIZE;
  toptions.c_cflag |= CS8;
  /* Canonical mode */
  toptions.c_lflag |= ICANON;
  /* commit the serial port settings */
  tcsetattr(fd, TCSANOW, &toptions);

  /* Send byte to trigger Arduino to send string back */
  write(fd, "0", 1);
  /* Receive string from Arduino */
  n = read(fd, buf, 64);
  /* insert terminating zero in the string */
  buf[n] = 0;

  printf("%i bytes read, buffer contains: %s\n", n, buf);

  if(DEBUG)
    {
      printf("Printing individual characters in buf as integers...\n\n");
      for(i=0; i<n; i++)
    {
      printf("Byte %i:%i, ",i+1, (int)buf[i]);
    }
      printf("\n");
    }

  return 0;
}

void loop()
{
  if (Serial.available() > 0)
  {
    Serial.println("Hello");
    Serial.read();
  }
}

Answer 1

就open（）而言，您的代码在我看来是正确的。

我相信open（）会阻塞，直到另一端可用为止。它在等待司机承认它可以说话，在此之前，它耐心地（顽固地）等待。请确保正在连接的设备已启动并准备好进行通信。

您还可以尝试标记O_NONBLOCK，它可以设置errno，以便检查open（）失败的原因。