serial.c

来自「The source code example of ARM9 developm」· C语言 代码 · 共 76 行

/*
 *	Description: 
 *		serial port example
 *		matrix P1 set 19200bps, n81, RTS/CTS flow control. and echo back the received data.
 *
 *		What is shown in this example:
 *		1. How to open a serial port
 *		2. How to set interface
 *		3. How to set baudrate, flow control and other settings
 *		4. How to read and write a serial port
 *		
 */
#include <stdio.h>
#include <termios.h>
#include <errno.h>
#include <fcntl.h>

#include "matrix500.h"

int
main(argc, argv)
	int	argc;
	char	*argv[];
{

	int	fd, interface, ret;
	char	buf[1024];
	struct termios T_new;

	/*open tty port*/
	fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);
	if (fd == -1) {
		printf("open /dev/ttyS0 Failed, errno: %d\r\n", errno);
		return 0;
	}

	/*set serial interface: RS-232*/
	interface = UC500_UART_TYPE_232;
	if(ioctl(fd, UC500_SET_UART_TYPE, &interface) != 0) {
		printf("set UART type: %d...Failed, errno: %d\r\n", interface, errno);
		close(fd);
		return 0;
	}

	/*termios functions use to control asynchronous communications ports*/
        if (tcgetattr(fd, &T_new) != 0) {	/*fetch tty state*/
		printf("tcgetattr failed. errno: %d\r\n", errno);
		close(fd);
		return 0; 
        }

	/*set 	19200bps, n81, RTS/CTS flow control, 
		ignore modem status lines, 
		hang up on last close, 
		and disable other flags*/
        T_new.c_cflag = (B19200 | CS8 | CREAD | CLOCAL | HUPCL | CRTSCTS); 	
        T_new.c_oflag = 0;
        T_new.c_iflag = 0;
        T_new.c_lflag = 0;
        if (tcsetattr(fd, TCSANOW, &T_new) != 0) {
		printf("tcsetattr failed. errno: %d\r\n", errno);
		close(fd);
		return 0; 
        }

	while(1) {
		/*when data received, send them back*/
		ret = read(fd, buf, sizeof(buf));
		if (ret > 0) {
			write(fd, buf, ret);
		}
	}

	return 0;
}