linux串口发ASCII命令
我有一个读卡器，可以读写磁条卡。我想在linux下用C语言来控制该读卡器，但是不知道如何用C语言来发送和接收ASCII命令。请教了！ 串口吗？ 打开串口设备，设置好波特率什么的，然后读写就好了 打开成功，读写有问题。有谁做过这样的东西吗?可否给我来个例子。 我用python写过读取条形码的小程序。你不说有什么问题，叫别人怎么和你说？ 贴出代码来看看 打开成功，读写有问题。有谁做过这样的东西吗?可否给我来个例子。
设置硬件驱动的问题吧，
下面是串口的操作/dev/ttyS0
int OpenDev(char *);
void Set_speed(int fd, int speed);
int Set_Parity(int fd,int databits,int stopbits,int parity);
int main(int argc, char **argv)
{
int fd;
int nread;
char buff[512];
char *dev= argv[1]; /* serial 2 */
memset(buff,'a',sizeof(buff) - 1);
buff[sizeof(buff) - 1] = '\0';
if (argc != 2) {
pritnf("Usage: %s serialport\n",argv[0]);
exit(1);
}
fd = OpenDev(argv[1]); /* open the device */
if (fd == -1) {
exit(1);
}
Set_speed(fd, 19200); /* set serial baud */
if (Set_Parity(fd, 8, 1, 'N') == FALSE) {
printf("Set Parity Error\n");
exit (1);
}
while (1) {
puts("ready to read!\n");
while ((nread = read(fd, buff, 512)) > 0) {
printf("\nLen %d\n",nread);
buff[nread+1] = '\0';
printf( "\n%s", buff);
}
}
close(fd);
return 0;
}
/* open device */
int
OpenDev(char *Dev)
{
int fd = open( Dev, O_RDWR );
//int fd = open(Dev, O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("Can't Open Serial Port");
return -1;
}
else
return fd;
}
/**
*@brief设置串口通信速率
*@paramfd 类型 int打开串口的文件句柄
*@paramspeed类型 int串口速度
*@returnvoid
*/
void
Set_speed(int fd, int speed)
{
int i;
int status;
struct termios Opt;
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, };
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 fd");
return;
}
tcflush(fd,TCIOFLUSH);
}
}
}
/**
*@brief 设置串口数据位，停止位和效验位
*@paramfd 类型int打开的串口文件句柄
*@paramdatabits 类型int 数据位 取值 为 7 或者8
*@paramstopbits 类型int 停止位 取值为 1 或者2
*@paramparity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 get");
return(FALSE);
}
options.c_cflag &= ~CSIZE;
/* set databit */
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);
}
/* set paritybit */
switch (parity){
case 'n':
case 'N': /* not parity */
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);
}
/* set stop bit */
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);
/* set timeout 15 seconds */
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 set");
return (FALSE);
}
return (TRUE);
}
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