- 论坛徽章:
- 0
|
一个串口编程的问题,只能写不能读
你的serial有数据输入吗?没有的话是没有数据的
IBM developerWorks上有文章,下面是代码
- #include <stdio.h>; /*标准输入输出定义*/
- #include <stdlib.h>; /*标准函数库定义*/
- #include <unistd.h>; /*Unix标准函数定义*/
- #include <sys/types.h>; /**/
- #include <sys/stat.h>; /**/
- #include <fcntl.h>; /*文件控制定义*/
- #include <termios.h>; /*PPSIX终端控制定义*/
- #include <errno.h>; /*错误号定义*/
- #define TRUE 1
- #define FALSE 0
- /***@brief 设置串口通信速率
- *@param fd 类型 int 打开串口的文件句柄
- *@param speed 类型 int 串口速度
- *@return void*/
- 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);
- }
- }
- /**
- *@brief 设置串口数据位,停止位和效验位
- *@param fd 类型 int 打开的串口文件句柄*
- *@param databits 类型 int 数据位 取值 为 7 或者8*
- *@param stopbits 类型 int 停止位 取值为 1 或者2*
- *@param parity 类型 int 效验类型 取值为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) /*设置数据位数*/
- {
- 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); /* 设置为奇效验*/
- options.c_iflag |= INPCK; /* Disnable parity checking */
- break;
- case 'e':
- case 'E':
- options.c_cflag |= PARENB; /* Enable parity */
- options.c_cflag &= ~PARODD; /* 转换为偶效验*/
- 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);
- }
- /* 设置停止位*/
- 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 打开串口
- */
- int OpenDev(char *Dev)
- {
- int fd = open( Dev, O_RDWR ); //| O_NOCTTY | O_NDELAY
- if (-1 == fd)
- { /*设置数据位数*/
- 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/ttyS1";
- fd = OpenDev(dev);
- if (fd>;0)
- set_speed(fd,19200);
- else
- {
- printf("Can't Open Serial Port!\n");
- exit(0);
- }
- if (set_Parity(fd,8,1,'N')== FALSE)
- {
- printf("Set Parity Error\n");
- exit(1);
- }
- while(1)
- {
- while((nread = read(fd,buff,512))>;0)
- {
- printf("\nLen %d\n",nread);
- buff[nread+1]='\0';
- printf("\n%s",buff);
- }
- }
- //close(fd);
- //exit(0);
- }
复制代码 |
|