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serial.c
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serial.c
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/* Port configuration partially based on great example "Arduino-serial" by
* Tod E. Kurt.
* http://todbot.com/blog/2006/12/06/arduino-serial-c-code-to-talk-to-arduino/
*
* Header from Tod's source file:
*
* Created 5 December 2006
* Copyleft (c) 2006, Tod E. Kurt, tod@todbot.com
* http://todbot.com/blog/
*/
#define _BSD_SOURCE /* CRTSCTS */
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <sys/ioctl.h>
#include "serial.h"
/*
* Open serial port from name and baud rate and return file desciptor.
*/
int serial_init(const char* serialport, int baud)
{
struct termios toptions;
int serial;
speed_t brate;
serial = open(serialport, O_RDWR | O_NOCTTY);
if (serial == -1)
return -1;
if (tcgetattr(serial, &toptions) < 0)
return -1;
switch (baud) {
#ifdef B4800
case 4800:
brate=B4800;
break;
#endif
#ifdef B9600
case 9600:
brate=B9600;
break;
#endif
#ifdef B14400
case 14400:
brate=B14400;
break;
#endif
#ifdef B19200
case 19200:
brate=B19200;
break;
#endif
#ifdef B28800
case 28800:
brate=B28800;
break;
#endif
#ifdef B38400
case 38400:
brate=B38400;
break;
#endif
#ifdef B57600
case 57600:
brate=B57600;
break;
#endif
#ifdef B115200
case 115200:
brate=B115200;
break;
#endif
#ifdef B250000
case 250000:
brate=B250000;
break;
#endif
#ifdef B230400
case 230400:
brate=B230400;
break;
#endif
#ifdef B460800
case 460800:
brate=B460800;
break;
#endif
#ifdef B500000
case 500000:
brate=B460800;
break;
#endif
#ifdef B576000
case 576000:
brate=B576000;
break;
#endif
default:
perror("Invalid baudrate");
return -1;
}
cfsetispeed(&toptions, brate);
cfsetospeed(&toptions, brate);
/* 8N1 */
toptions.c_cflag &= ~PARENB;
toptions.c_cflag &= ~CSTOPB;
toptions.c_cflag &= ~CSIZE;
toptions.c_cflag |= CS8;
/* no flow control */
toptions.c_cflag &= ~CRTSCTS;
/* turn on READ & ignore ctrl lines */
toptions.c_cflag |= CREAD | CLOCAL;
/* turn off s/w flow ctrl */
toptions.c_iflag &= ~(IXON | IXOFF | IXANY);
/* make raw */
toptions.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
toptions.c_oflag &= ~OPOST;
/* set blocking method */
toptions.c_cc[VMIN] = SERIAL_VMIN;
toptions.c_cc[VTIME] = SERIAL_VTIME;
if (tcsetattr(serial, TCSANOW, &toptions) < 0)
return -1;
return serial;
}
/*
* Read a complete line from the serial port
*/
int serial_getline(int serial, char *buffer, int timeout)
{
int nbytes, i = 0;
int retries = (timeout * 10) / SERIAL_VTIME;
char byte[1];
do {
/* Block until one character received or timeout */
nbytes = read(serial, byte, 1);
/* Return if in error state */
if (nbytes == -1)
return -1;
/* Try again if timed out */
if (nbytes == 0) {
retries--;
continue;
}
/* Otherwise add the new byte to the buffer */
buffer[i] = byte[0];
i++;
} while (byte[0] != '\n' && retries > 0);
/* Remove end of line characters and null terminate the string */
if (buffer[i - 2] == '\r')
i -= 2;
else
i -= 1;
buffer[i] = 0;
return i;
}