thermistor_check.comp

/******************************************************************************
 *
 * Copyright (C) 2014 Alexander Rössler
 *
 *
 * This module checks the functionality of thermistors
 *
 ******************************************************************************
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * THE AUTHORS OF THIS PROGRAM ACCEPT ABSOLUTELY NO LIABILITY FOR
 * ANY HARM OR LOSS RESULTING FROM ITS USE.  IT IS _EXTREMELY_ UNWISE
 * TO RELY ON SOFTWARE ALONE FOR SAFETY.  Any machinery capable of
 * harming persons must have provisions for completely removing power
 * from all motors, etc, before persons enter any danger area.  All
 * machinery must be designed to comply with local and national safety
 * codes, and the authors of this software can not, and do not, take
 * any responsibility for such compliance.
 *
 * This code was written as part of the LinuxCNC project.  For more
 * information, go to www.linuxcnc.org.
 *
 ******************************************************************************/

component thermistor_check "LinuxCNC HAL component for checking functionality of thermistors";
pin in  float   temp      "Temperature input";
pin in  float   min_temp  "The minimum temperature change that should count";
pin in  float   pid       "Output of PID control";
pin in  float   min_pid   "The minimum PID control output to react to";
pin in  float   bias      "Bias for the PID input. Can be used to correct errors due to cooling.";
pin in  float   wait      "Time to wait before triggering an error in secods";
pin in  bit     enable    "Enables or disables the component, out is TRUE when disabled";
pin out bit     no_error  "Output value -> TRUE when the thermistor works as exspected";
pin out bit     error     "Error value -> FALSE when the thermistor works as exspected";
function _  fp "Update the output value";
description """
Component for checking functionality of thermistors
.LP
TODO
""";
license "GPL";
variable hal_float_t last_temp = 0.0;
variable hal_bit_t last_enable = 0;
variable hal_float_t oldwait = 0.0;
variable int t_secs = 0;
variable int t_nsecs = 0;
variable int c_secs = 0;
variable int c_nsecs = 0;
variable hal_bit_t start = 0;
;;
FUNCTION(_) {
    float temp_change;
    float time;
    
    if (wait != oldwait)
    {
        time = wait;
        if (time < 0) time = 0; // no negative timeout periods
        // new timeout, convert to secs/ns
        oldwait = time;
        t_secs = time;
        time -= t_secs;
        t_nsecs = (1e9 * time);
        
        if (enable) {
            // reset
            start = 1;
        }
    }

    if ((enable) && (pid >= (min_pid+bias)))
    {
        if (start == 1)
        {
            // reset
            c_secs = t_secs;
            c_nsecs = t_nsecs;
            last_temp = temp;
            start = 0;
        }
        else
        {
            c_nsecs -= period;
            if (c_nsecs < 0)
            {
                c_nsecs += 1000000000;
                if (c_secs > 0) 
                {
                    c_secs--;
                }
                else
                {
                    start = 1; // restart
                }
            }
            
            if (start == 1)
            {
                temp_change = temp - last_temp;

                if (temp_change >= min_temp)    // correct
                {
                    no_error = 1;
                    error = 0;
                }
                else
                {
                    no_error = 0;
                    error = 1;
                }
            }
        }
    }
    else
    {
        start = 1;
        no_error = 1;
        error = 0;
    }
}