之前一直在纠结这个怎么做，其实就是一个读写文件的流程，需要配置下串口的参数。
不过有意思的地方更在于，一，串口是可以作为终端的，linux终端tty是很有意思的，二，串口的配置涉及缓冲区设计，这点又和C语言的缓冲区息息相关，很多公司也喜欢考这样的C语言问题。
参考文献为：
其中，IBM的源码为：
[cpp]
- #include<stdio.h>
- #include<stdlib.h>
- #include<unistd.h>
- #include<sys/types.h>
- #include<sys/stat.h>
- #include<fcntl.h>
- #include<termios.h>
- #include<errno.h>
- #define FALSE -1
- #define TRUE 0
- int speed_arr[] = { B38400, B19200, B9600, B4800, B2400, B1200, B300,B38400, B19200, B9600, B4800, B2400, B1200, B300, };
- int name_arr[] = {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);
- }
- }
- }
- 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)
- {
- 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);
- options.c_iflag |= INPCK; /* Disnable parity checking */
- break;
- case 'e':
- case 'E':
- options.c_cflag |= PARENB; /* Enable parity */
- options.c_cflag &= ~PARODD;
- 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);
- }
- 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;
- tcflush(fd,TCIFLUSH);
- options.c_cc[VTIME] = 150;
- options.c_cc[VMIN] = 0; /* Update the options and do it NOW */
- if (tcsetattr(fd,TCSANOW,&options) != 0)
- {
- perror("SetupSerial 3");
- return (FALSE);
- }
- return (TRUE);
- }
- int main()
- {
- printf("STDIO COM1\n");
- int fd;
- fd = open("/dev/ttyS0",O_RDWR);
- if(fd == -1)
- {
- perror("serialport error\n");
- }
- else
- {
- printf("open ");
- printf("%s",ttyname(fd));
- printf(" succesfully\n");
- }
- set_speed(fd,115200);
- if (set_Parity(fd,8,1,'N') == FALSE) {
- printf("Set Parity Error\n");
- exit (0);
- }
- char buf = 'c';
- write(fd,&buf,1);
- close(fd);
- return 0;
- }
51cto的这本书讲解较为详细，对每项参数有详细解释：
[cpp]
- #include<stdio.h>
- #include<stdlib.h>
- #include<fcntl.h>
- #include<unistd.h>
- #include<errno.h>
- #include<termios.h>
- #include<sys/types.h>
- #include<sys/stat.h>
- int main()
- {
- printf("COM1 test program\n");
- int fd;
- fd = open("/dev/ttyS0",O_RDWR);
- if(fd == -1)
- {
- perror("serialport error\n");
- }
- else{
- printf("open %s succesfully\n", ttyname(fd));
- }
- struct termios Opt;
- int status;
- tcgetattr(fd, &Opt);
- //set speed
- cfsetispeed(&Opt, B115200);
- cfsetospeed(&Opt, B115200);
- //set databits
- Opt.c_cflag &= ~CSIZE;
- Opt.c_cflag |= CS8;
- //set parity
- Opt.c_cflag &= ~PARENB;
- Opt.c_iflag &= ~INPCK;
- //set stopbits
- Opt.c_cflag &= ~CSTOPB;
- tcsetattr(fd, TCSANOW, &Opt);
- status = tcsetattr(fd, TCSANOW, &Opt);
- if(status != 0)
- {
- perror("tcsetattr fd1");
- return;
- }
- char buf = 'd';
- write(fd, &buf, 1);
- close(fd);
- return 0;