/*****************************************************************************
 *
 * Camera Panning Control V1.0.
 *
 * compile with: gcc -O campan.c -o campan
 *
 * campan is a simple program to interface with Garry Ellard's PIC Stepper
 * Motor Circuit. This version uses the modem control lines on ttys0 to pan
 * a webcam left or right and will indicate when end stop switches are
 * activated.
 *
 * Modem control lines: DTR - direction  Left +12V Right -12V (pin 4)
 *                      RTS - move       Move +12V Stop  -12V (pin 7)
 *                      CTS - left stop  ~Lstop +12V Lstop -12V (pin 8)
 *                      DSR - right stop ~Rstop +12V Rstop -12V (pin 6)
 *                      Gnd - signal ground 0V (pin 5)
 *
 * Archie Howitt 4 April 2003
 *
 * reference:
 * http://www.easysw.com/~mike/serial/serial.html
 * http://www.geocities.com/SiliconValley/Park/4572/tips.html
 * http://docsrv.caldera.com:8457/en/SerialProg/Serial-Programming-HOWTO.html
 *
 *****************************************************************************/

#include <stdio.h>           // Standard input/output definitions
#include <string.h>          // String function definitions
#include <unistd.h>          // UNIX standard function definitions
#include <fcntl.h>           // File control definitions
#include <errno.h>           // Error number definitions
//#include <termios.h>       // POSIX terminal control definitions
#include <asm/termios.h>     // terminal control definitions

#define left   TIOCM_DTR;    // pan direction left  - DTR +12V (space)
#define right ~TIOCM_DTR;    // pan direction right - DTR -12V (mark)
#define stop   TIOCM_RTS;    // stop panning        - RTS +12V (space)
#define move  ~TIOCM_RTS;    // pan                 - RTS -12V (mark)

struct termios options;      // TERMIOS structure for local port
int fd;                      // File Descriptor for the port
int status;                  // port status store



/*********************************************
 * 'open_port()' - Open serial port 1.
 *
 * Returns the Port file descriptor on success or -1 on error.
 * 
 */

int open_port(void)
{
  fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
  if (fd == -1)
  {
    // Could not open the port.
    perror("open_port: Unable to open /dev/ttyf1 - ");
  }
  else
    {
      fcntl(fd, F_SETFL, 0);   // clear the port flags
    }
  return (fd);
}


/********************************************
 * 'getch()' - get character from keyboard.
 *
 */

int getch()
{
  int c, i, fd=0;
  struct termios term, oterm;
  
  tcgetattr(fd, &oterm);                // get the terminal settings

  memcpy(&term, &oterm, sizeof(term));  // make a copy of the settings

  term.c_lflag = term.c_lflag & (!ICANON);  // terminal in non-canonical mode
  term.c_cc[VMIN] = 1;                  // set - read one character
  term.c_cc[VTIME] = 0;                 // set - return immediately
  tcsetattr(fd, TCSANOW, &term);        // set terminal to this

  c=getchar();                      // get a character

  tcsetattr(fd, TCSANOW, &oterm);  // reset the terminal to its original state

  return c;                       // return the charcter
}


/*******************************************
 * 'stepmove ()' - pulse the stepper motor
 *
 * entry - direction character 'l' or 'r'
 * return - number of step pulses moved
 *
 * left end stop switch on modem control line CTS
 * right end stop switch on modem control line DSR
 *
 */

int stepmove (char direction)
{

  int t1, t2, pstep, s;
  int pcount = 0;           // number of step pulses moved
  int endstop = 0;          // pan end stop indicator

  printf("Enter number of pan steps: ");
  s = scanf("%d", &pstep);         // get the number of pan steps

  if(s==0){                               // did scanf() format fail?
    printf("Input must be a number!\n");  // ouch! numbers only
    getch();                              // clear the keyboard buffer
    getch();                              // twice ?? OK it works
    return pcount;
  }

  getch();                     // always clear the keyboard buffer
                               // after scanf()

  // now pan number of step pulses checking the end stop switches each time
  while((pcount < pstep) && !(endstop)) {

    ioctl(fd, TIOCMGET, &status);      // get the port status

   if(!(status & TIOCM_CTS) && (direction == 'l')) {   // hit left stop?
      endstop++;                                        // yes
      printf("We've hit Left stop!!!\n");
    }
    if(!(status & TIOCM_DSR) && (direction =='r')) {    // hit right stop?
      endstop++;                                        //yes
      printf("We've hit Right stop!!!\n");
    }

    if(endstop)                // did we hit an end stop?
      break;                   // if so end out
    
    status &= move;            // no we didn't hit an end stop so pulse move
    ioctl(fd, TIOCMSET, &status);

    for(t1=0; t1<9999; t1++) {
      for (t2=0; t2<999; t2++);
    }

    ioctl(fd, TIOCMGET, &status);
    status |= stop;
    ioctl(fd, TIOCMSET, &status);

    for(t1=0; t1<9999; t1++) {
      for (t2=0; t2<999; t2++);
    }
    
    pcount++;                   // bump pulse counter
    //printf("Number of pulses = %d\n", pcount);
  }
  return pcount;
}

/***************************************************
 * 'pancommand()' get direction command 'l' - Left
 *                                      'r' - Right
 *                                      'q' - quit
 *
 * direction indicated by modem control line DTR - left  DTR +12V (space)
 *                                               - right DTR -12V (mark)
 * return - command 'l', 'r' or 'q'
 */

int pancommand (void)
{
  char c;        // command
  int numstep;   // returned step counts

  printf("Enter Command (l, r or q): "); c = getch(); printf("%c\n",c);

  switch (c){
  case 'l':                           // left
    ioctl(fd, TIOCMGET, &status);
    status |= left;
    ioctl(fd, TIOCMSET, &status);

    printf("Direction set as: LEFT (DTR +12V - space)\n");
    
    numstep = stepmove(c);
    break;
  case 'r':                          // right
    ioctl(fd, TIOCMGET, &status);
    status &= right;
    ioctl(fd, TIOCMSET, &status);

    printf("Direction set as: RIGHT (DTR -12V - mark)\n");

    numstep = stepmove(c);
    break;
  case 'q':
    numstep = 0;
    break;
  default:
    printf("Command: %c  - not supported. Enter l for Left r for Right q to quit.\n", c);

  }
  if((c == 'l') || (c == 'r'))
    printf("Number of step pulses actually moved = %d\n", numstep);

  return c;
}

/************************************************
 * 'main ()'
 *
 */

main () {

  char quit=0;

  open_port ();               // open serial port and get file descriptor

  printf("Start program - RTS & DTR +12V (space)\n");

  while(quit != 'q'){
    quit = pancommand();      // request command - 'q' quits program
  }

  close (fd);    // close port
}