Code:
#include <termios.h>
int openserial(const char *portfilename, long baudrate, long baudrate_target) {
struct termios options;
int fd;
fprintf(stderr,"Opening serial port %s, this can take a while\n", portfilename);
fd = open(portfilename, O_RDWR | O_NOCTTY | O_NDELAY);
// fd = open(portfilename, O_RDWR | O_NOCTTY);
if(fd == -1) {
perror(portfilename);
} else {
fcntl(fd, F_SETFL, 0);
// Get the current options for the port
tcgetattr(fd, &options);
options.c_cflag |= (CLOCAL | CREAD);
options.c_lflag &= !(ICANON | ECHO | ECHOE | ISIG);
options.c_oflag &= !(OPOST);
options.c_cc[VMIN] = 0;
options.c_cc[VTIME] = 100;
tcsetattr(fd, TCSANOW, &options);
long current_baud = 9600;
if(0 != modifybaud(fd, baudrate)) {
fprintf(stderr, "Error modifying baudrate. Continuing, but may suffer issues\n");
} else {
if(baudrate != 0)
current_baud = baudrate;
}
// Reset the device. Some software changes settings and then leaves it
blindcmd(fd,"ATZ",1);
// printf("Baudrate upgrader disabled\n");
if(0 > upgradebaudrate(fd, baudrate_target, current_baud)) {
fprintf(stderr, "Error upgrading baudrate. Continuing, but may suffer issues\n");
}
// Now some churn to get everything up and running.
// Do a general cmd that all obd-devices support
// Do this once in case we have a partially-written command somehow
blindcmd(fd,"0100",1);
// Disable command echo [elm327]
blindcmd(fd,"ATE0",1);
// Disable linefeeds [an extra byte of speed can't hurt]
blindcmd(fd,"ATL0",1);
// Don't insert spaces [readability is for ugly bags of mostly water]
blindcmd(fd,"ATS0",1);
// Then do it again to make sure the command really worked
blindcmd(fd,"0100",1);
}
return fd;
}
// Blindly send a command and throw away all data to next prompt
/**
\param cmd command to send
\param no_response if we don't read to next prompt [ie, on exit]
\param fd file descriptor
*/
void blindcmd(int fd, const char *cmd, int no_response) {
char outstr[1024];
snprintf(outstr, sizeof(outstr), "%s%s\0", cmd, OBDCMD_NEWLINE);
appendseriallog(outstr, SERIAL_OUT);
write(fd,outstr, strlen(outstr));
if(0 != no_response) {
sleep(1);
readtonextprompt(fd);
}
}
/// Throw away all data until the next prompt
void readtonextprompt(int fd) {
char retbuf[4096]; // Buffer to store returned stuff
readserialdata(fd, retbuf, sizeof(retbuf));
}
/// Collect data up to the next prompt
/** Reads up to the next '>'
\param buf buffer to fill
\param n size of buf
\return number of bytes put in buf, or -1 on error
*/
int readserialdata(int fd, char *buf, int n) {
char *bufptr = buf; // current position in buf
struct timeval start,curr; // For timing out
if(0 != gettimeofday(&start, NULL)) {
perror("Couldn't gettimeofday");
return -1;
}
memset((void *)buf, '\0', n);
int retval = 0; // Value to return
int nbytes; // Number of bytes read
do {
nbytes = read(fd, bufptr, buf+n-bufptr-1);
if(-1 == nbytes && EAGAIN != errno) {
perror("Error in readserialdata");
}
if(-1 != nbytes) {
// printf("Read bytes '%s'\n", bufptr);
retval += nbytes; // Increment bytecount
bufptr += nbytes; // Move pointer forward
}
if(0 != gettimeofday(&curr, NULL)) {
perror("Couldn't gettimeofday");
return -1;
}
if(OBDCOMM_TIMEOUT < 1000000l*(curr.tv_sec - start.tv_sec) +
(curr.tv_usec - start.tv_usec)) {
printf("Timeout!\n");
return -1;
}
} while (retval == 0 || bufptr[-1] != '>');
appendseriallog(buf, SERIAL_IN);
return retval;
}
Adv Reply
Originally Posted by xb12x
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