Linux(妙算)串口通信

妙算上搭載的Linux，其串口操作與普通Linux相同。
通過官方文檔可知，妙算共有四個串口可用，
本次實驗使用串口1，其對應的設備爲/dev/ttyTHS0,爲盒子上的13和15號引腳。
其接線如圖所示

代碼

#include <stdio.h>      /*標準輸入輸出定義*/
#include <stdlib.h>     /*標準函數庫定義*/
#include <unistd.h>     /*Unix標準函數定義*/
#include <sys/types.h>  /**/
#include <sys/stat.h>   /**/
#include <fcntl.h>      /*文件控制定義*/
#include <termios.h>    /*PPSIX終端控制定義*/
#include <errno.h>      /*錯誤號定義*/

/*@brief  設置串口通信速率
 *@param  fd     類型 int  打開串口的文件句柄
 *@param  speed  類型 int  串口速度
 *@return  void
 */
#define FALSE 1
#define TRUE 0

char *recchr="We received:\"";

int speed_arr[] = { B921600, B460800, B230400, B115200, B57600, B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {921600, 460800, 230400, 115200, 57600, 38400,  19200,  9600,  4800,  2400,  1200,  300, 38400,  19200,  9600, 4800, 2400, 1200,  300, };
void set_speed(int fd, int speed)
{
  int   i;
  int   status;
  struct termios   Opt;
  tcgetattr(fd, &Opt);
  for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++)
   {
    if  (speed == name_arr[i])
    {
        tcflush(fd, TCIOFLUSH);
     cfsetispeed(&Opt, speed_arr[i]);
     cfsetospeed(&Opt, speed_arr[i]);
     status = tcsetattr(fd, TCSANOW, &Opt);
     if  (status != 0)
            perror("tcsetattr fd1");
      return;
      }
   tcflush(fd,TCIOFLUSH);
   }
}
/*
 *@brief  設置串口數據位，停止位和效驗位
 *@param  fd       類型  int  打開的串口文件句柄*
 *@param  databits 類型  int  數據位   取值 爲 7 或者8*
 *@param  stopbits 類型  int  停止位   取值爲 1 或者2*
 *@param  parity   類型  int  效驗類型 取值爲N,E,O,,S
 */
int set_Parity(int fd,int databits,int stopbits,int parity)
{
 struct termios options;
 if  ( tcgetattr( fd,&options)  !=  0)
  {
   perror("SetupSerial 1");
   return(FALSE);
  }
  options.c_cflag &= ~CSIZE;
  switch (databits) /*設置數據位數*/
  {
   case 7:
    options.c_cflag |= CS7;
    break;
   case 8:
  options.c_cflag |= CS8;
  break;
 default:
  fprintf(stderr,"Unsupported data size\n");
  return (FALSE);
 }
  switch (parity)
   {
   case 'n':
 case 'N':
  options.c_cflag &= ~PARENB;   /* Clear parity enable */
  options.c_iflag &= ~INPCK;     /* Enable parity checking */
  break;
 case 'o':
 case 'O':
  options.c_cflag |= (PARODD | PARENB);  /* 設置爲奇效驗*/
  options.c_iflag |= INPCK;             /* Disnable parity checking */
  break;
 case 'e':
 case 'E':
  options.c_cflag |= PARENB;     /* Enable parity */
  options.c_cflag &= ~PARODD;   /* 轉換爲偶效驗*/ 
  options.c_iflag |= INPCK;       /* Disnable parity checking */
  break;
 case 'S':
 case 's':  /*as no parity*/
  options.c_cflag &= ~PARENB;
  options.c_cflag &= ~CSTOPB;
  break;
 default:
  fprintf(stderr,"Unsupported parity\n");
  return (FALSE);
  }
  /* 設置停止位*/  
  switch (stopbits)
   {
   case 1:
    options.c_cflag &= ~CSTOPB;
  break;
 case 2:
  options.c_cflag |= CSTOPB;
  break;
 default:
  fprintf(stderr,"Unsupported stop bits\n");
  return (FALSE);
 }
  /* Set input parity option */
  if (parity != 'n')
    options.c_iflag |= INPCK;
    options.c_cc[VTIME] = 150; // 15 seconds
    options.c_cc[VMIN] = 0;

  tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */
  if (tcsetattr(fd,TCSANOW,&options) != 0)
   {
    perror("SetupSerial 3");
  return (FALSE);
 }
  return (TRUE);
 }
/*
 *@breif 打開串口
 */
int OpenDev(char *Dev)
{
int fd = open( Dev, O_RDWR | O_NONBLOCK);         //| O_NOCTTY | O_NDELAY
 if (-1 == fd)
  { /*設置數據位數*/
   perror("Can't Open Serial Port");
   return -1;
  }
 else
 return fd;

}
/*
 *@breif  main()
 */
int main(int argc, char *argv[])
{
    int fd;
    int nread;
    char buff[512];
    char *dev ="/dev/ttyTHS0"; //Uart1
    char recchr[512];
    int temp=0;
    sleep(1);

    fd = OpenDev(dev); //1open uart

    if (fd>0)
    {
        set_speed(fd,9600); //2set speed
    }
    else{
        printf("Can't Open Serial Port!\n");
        exit(0);
    }

    if (set_Parity(fd,8,1,'N')== FALSE) //3set parity
    {
        printf("Set Parity Error\n");
        exit(1);
    }
while(1)
{
    //read
    if(nread=read(fd,buff,512)>0)
    {
        //printf("\nLen %d\n",nread);
        buff[nread]='\0';
        printf("received data:%s\n",buff);
    }

    temp++;
    sprintf(recchr,"%04d",temp);
    //write
    write(fd, recchr, strlen(recchr));
    printf("data:%d,send ok！\n",temp);
    sleep(1);
}
    close(fd);
    exit(0);
}