pulseIn.c

/*
 * @file pulseIn.c
 *
 * @author Andy Lindsay
 *
 * @version 0.85
 *
 * @copyright Copyright (C) Parallax, Inc. 2012.  See end of file for
 * terms of use (MIT License).
 *
 * @brief pulseIn function source, see simpletools.h for documentation.
 *
 * @detail Please submit bug reports, suggestions, and improvements to
 * this code to editor@parallax.com.
 */
 
#include "simpletools.h"                      // simpletools function prototypes
 
long pulse_in(int pin, int state)              // pulseIn function definition
{
  /*
  if(st_iodt == 0)
  {
    set_io_dt(CLKFREQ/1000000);
    set_io_timeout(CLKFREQ/4);
  }
  */
  long tPulse;
  int ctr = ((8 + ((!state & 1) * 4)) << 26) + pin;
  input(pin);
  long tf = st_timeout;
  long t = CNT;
  while((get_state(pin) == state) && (CNT - t < tf));
  if(CTRA == 0)
  {
    CTRA = ctr;
    FRQA = 1;
    PHSA = 0;
    while((PHSA == 0) && (CNT - t < tf));
    while((get_state(pin) == state) && (CNT - t < tf));
    CTRA = 0;
    tPulse = PHSA/st_iodt;
  }
  else if(CTRB == 0)
  {
    CTRB = ctr;
    FRQB = 1;
    PHSB = 0;
    while((PHSB == 0) && (CNT - t < tf));
    while((get_state(pin) == state) && (CNT - t < tf));
    CTRB = 0;
    tPulse = PHSB/st_iodt;
  }
  else
  {
    tPulse = -1;
  }
  return tPulse;
}