485_send_data.c

linux 485欻串口编程示例

// this is a test about Full 485 
// hardware : MAX488

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <fcntl.h>      // open() close()
#include <unistd.h>     // read() write()

#include <termios.h>    // set baud rate

#include "OURS_DEF.h"

#define DEVICE_TTYS "/dev/ttyS1"
#define MY_BAUD_RATE B9600

int func_485_send(int fd)
{
	ssize_t ret;
	char *send_buf="abcdefgh";		//Give the message to be send.
	
	while (1){
	        ret = write(fd,send_buf,strlen(send_buf));
        	if (ret == -1) {
                	printf ("write device %s error\n", DEVICE_TTYS);
	                return -1;
        	}
		sleep(1);
		printf("sending....................................\n");
		
	}

} // end func_485_send
//------------------------------------- init seriel port  ---------------------------------------------------
void init_ttyS(int fd)
{
        struct termios options;

        bzero(&options, sizeof(options));       	// clear options

        cfsetispeed(&options,MY_BAUD_RATE);            	// setup baud rate
        cfsetospeed(&options,MY_BAUD_RATE);

        options.c_cflag |= (CS8 | CLOCAL | CREAD);
        options.c_iflag = IGNPAR;

        tcflush(fd, TCIFLUSH);

        tcsetattr(fd, TCSANOW, &options);

}//end init_ttyS

void init_CPLD()
	{
		int ret;
		int fd;		

		fd=open("/dev/CPLD",O_RDWR);	//CPLD is a device that should be insmod before this program.
		if (fd<0)
                {
                        printf("Open device CPLD error\n");
                }
                else
                {
                        printf("Open device CPLD success\n");
                }
        	//getchar();

		ret=ioctl(fd,READ_CPLD_CTL,0);
		printf(" CPLD_CTL is %x\n", ret);

		ioctl(fd,WRITE_CPLD_CTL,0x20);
		
		ret=ioctl(fd,READ_CPLD_CTL,0);
                printf(" CPLD_CTL is %x\n", ret);

		ret=ioctl(fd,READ_XGPIO_OUT,0);
                printf(" XGPIO_OUT is %x\n", ret);

		ioctl(fd,WRITE_XGPIO_OUT,0xffff);	// Configure it to "send mode"

		ret=ioctl(fd,READ_XGPIO_OUT,0);
                printf(" XGPIO_OUT is %x\n", ret);

	}


//------------------------------------- main ----------------------------------------------------------------
int main(void)
{
        int fd;

        printf("\n 485 SEND DATAS \n\n");

        // open seriel port
        fd = open(DEVICE_TTYS, O_RDWR);

        if (fd == -1) {
                printf("open device %s error\n",DEVICE_TTYS);
        }
        else {
                init_ttyS(fd);  	// init device
		init_CPLD();		// Configure the CPLD
                func_485_send(fd);   	// 485 send datas functions

                // close ttyS0
                if (close(fd)!=0) printf("close device %s error",DEVICE_TTYS);
        }

        return 0;
}// end main