rs485-test.c

ARM9200+嵌入式linux下串口通信程序

/************************************************
 *  serial communication demo
 *  by Zou jian guo <[e-mail]>   
 *  2003-12-22
 *
*************************************************/


#include <termios.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <pthread.h>

#define BAUDRATE B115200
#define COM0 "/dev/ttyS0"
#define COM1 "/dev/ttyS1"
#define COM2 "/dev/ttyS2"
#define COM3 "/dev/ttyS3"
#define COM4 "/dev/ttyS4"

#define ENDMINITERM 27 /* ESC to quit miniterm */
#define FALSE 0
#define TRUE 1

volatile int STOP=FALSE;
volatile int fd,fd_pio;


/*******************************************************************/
void child_handler(int s)
{
  printf("stop!!!\n");
   STOP=TRUE;
}
/*******************************************************************/
void* keyboard(void * data)
{
    int c;
	for (;;){
		c=getchar();
      	if( c== ENDMINITERM){
        	STOP=TRUE;
        	break ;
      	}
	}
    return NULL;
}
/*******************************************************************/
/* modem input handler */
void* receive(void * data)
{
	int c;
  	printf("read modem\n");
  	while (STOP==FALSE) 
  	{
    	read(fd,&c,1); /* com port */
 	  	//write(fd,&c,1); /* stdout */
     	write(1,&c,1); /* stdout */
  	}
  	printf("exit from reading modem\n");
  	return NULL; 
}
/*******************************************************************/
void* send(void * data)
{
  	int c='0';
  	printf("send data\n");
  	while (STOP==FALSE) /* modem input handler */
  	{
    	c++;
    	c %= 255;
    	write(fd,&c,1); /* stdout */
    	usleep(1000000);
  	}
  	return NULL; /* wait for child to die or it will become a zombie */
}
/*******************************************************************/
int main(int argc,char** argv)
{

	struct termios oldtio,newtio,oldstdtio,newstdtio;
	struct sigaction sa;
	int ok;
 	pthread_t th_a, th_b, th_c;
 	void * retval;

	if(argc <2){
		printf("Usage: %s w|r \n",argv[0]);
		return 0;
	}
   	fd = open(COM2, O_RDWR );
	if (fd <0) {  
		perror(COM4);
    	exit(-1);
  	}

	fd_pio=open("/dev/pio/0",O_RDWR);
	if(fd_pio < 0){
		printf("####pio  device open fail####\n");
		return (-1);
	}

	
  	tcgetattr(0,&oldstdtio);
  	tcgetattr(fd,&oldtio); /* save current modem settings */
  	tcgetattr(fd,&newstdtio); /* get working stdtio */
//	newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;/*ctrol flag*/
	newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD;/*ctrol flag*/
	newtio.c_iflag = IGNPAR; /*input flag*/
	newtio.c_oflag = 0;		/*output flag*/
 	newtio.c_lflag = 0;
 	newtio.c_cc[VMIN]=1;
	newtio.c_cc[VTIME]=0;
 /* now clean the modem line and activate the settings for modem */
 	tcflush(fd, TCIFLUSH);
	tcsetattr(fd,TCSANOW,&newtio);/*set attrib	  */

  	sa.sa_handler = child_handler;
  	sa.sa_flags = 0;
  	sigaction(SIGCHLD,&sa,NULL); /* handle dying child */

	if(strcmp(argv[1],"w")==0){
		ioctl(fd_pio, 1, 1);
	  	pthread_create(&th_c, NULL, send, 0);
	}
	if(strcmp(argv[1],"r")==0){
		ioctl(fd_pio, 0, 1);
		pthread_create(&th_b, NULL, receive, 0);
	}
  	pthread_create(&th_a, NULL, keyboard, 0);
  	pthread_join(th_a, &retval);
  	pthread_join(th_b, &retval);
  	pthread_join(th_c, &retval);

  	tcsetattr(fd,TCSANOW,&oldtio); /* restore old modem setings */
  	tcsetattr(0,TCSANOW,&oldstdtio); /* restore old tty setings */
  	close(fd);
  	exit(0); 
}