rcTime.c

/*
 * @file rcTime.c
 *
 * @author Andy Lindsay
 *
 * @version 0.85
 *
 * @copyright Copyright (C) Parallax, Inc. 2012.  See end of file for
 * terms of use (MIT License).
 *
 * @brief rcTime 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 rc_time(int pin, int state)              // rcTime function definition
{
  /*
  if(st_iodt == 0)                               // If dt not initialized
  {
    set_io_dt(CLKFREQ/1000000);               // Set up timed I/O time increment
    set_io_timeout(CLKFREQ/4);                // Set up timeout
  }
  */
  long tDecay;                                // Declare tDecay variable
  int ctr = ((8 + ((!state & 1) * 4)) << 26); // POS detector counter setup
  ctr += pin;                                 // Add pin to setup
  long tf = st_timeout;                        // Set up timeout
  long t = CNT;                               // Mark current time
  if(CTRA == 0)                               // If CTRA unused
  {
    CTRA = ctr;                               // Configure CTRA
    FRQA = 1;                                 // FRQA increments PHSA by 1
    input(pin);                               // Set I/O pin to input
    PHSA = 0;                                 // Clear PHSA
    // Wait for decay or timeout
    while((input(pin) == state) && (CNT - t <= tf));
    CTRA = 0;                                 // Stop the counter module
    tDecay = PHSA/st_iodt;                       // Copy result to tDecay
  }
  else if(CTRB == 0)                          // If CTRA used, try CTRB
  {
    CTRB = ctr;                               // Same procedure as for CTRA
    FRQB = 1;
    input(pin); 
    PHSB = 0;
    while((input(pin) == state) && (CNT - t <= tf));
    CTRB = 0;
    tDecay = PHSB/st_iodt;
  }
  else                                        // If CTRA & CTRB in use
  {
    tDecay = -1;                              // Return -1
  }
  return tDecay;                              // Return measurement
}