MarlinFirmware/Marlin/temperature.cpp

/*
  temperature.c - temperature control
  Part of Marlin
  
 Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
 
 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 3 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, see <http://www.gnu.org/licenses/>.
 */

/*
 This firmware is a mashup between Sprinter and grbl.
  (https://github.com/kliment/Sprinter)
  (https://github.com/simen/grbl/tree)
 
 It has preliminary support for Matthew Roberts advance algorithm 
    http://reprap.org/pipermail/reprap-dev/2011-May/003323.html

 */


#include "Marlin.h"
#include "ultralcd.h"
#include "temperature.h"
#include "watchdog.h"

#include "Sd2PinMap.h"


//===========================================================================
//=============================public variables============================
//===========================================================================
int target_temperature[EXTRUDERS] = { 0 };
int target_temperature_bed = 0;
int current_temperature_raw[EXTRUDERS] = { 0 };
float current_temperature[EXTRUDERS] = { 0.0 };
int current_temperature_bed_raw = 0;
float current_temperature_bed = 0.0;
#ifdef TEMP_SENSOR_1_AS_REDUNDANT
  int redundant_temperature_raw = 0;
  float redundant_temperature = 0.0;
#endif

#ifdef PIDTEMPBED
  float bedKp=DEFAULT_bedKp;
  float bedKi=(DEFAULT_bedKi*PID_dT);
  float bedKd=(DEFAULT_bedKd/PID_dT);
#endif //PIDTEMPBED
  
#ifdef FAN_SOFT_PWM
  unsigned char fanSpeedSoftPwm;
#endif

unsigned char soft_pwm_bed;
  
#ifdef BABYSTEPPING
  volatile int babystepsTodo[3]={0,0,0};
#endif

#ifdef FILAMENT_SENSOR
  int current_raw_filwidth = 0;  //Holds measured filament diameter - one extruder only
#endif  
//===========================================================================
//=============================private variables============================
//===========================================================================
static volatile bool temp_meas_ready = false;

#ifdef PIDTEMP
  //static cannot be external:
  static float temp_iState[EXTRUDERS] = { 0 };
  static float temp_dState[EXTRUDERS] = { 0 };
  static float pTerm[EXTRUDERS];
  static float iTerm[EXTRUDERS];
  static float dTerm[EXTRUDERS];
  //int output;
  static float pid_error[EXTRUDERS];
  static float temp_iState_min[EXTRUDERS];
  static float temp_iState_max[EXTRUDERS];
  // static float pid_input[EXTRUDERS];
  // static float pid_output[EXTRUDERS];
  static bool pid_reset[EXTRUDERS];
#endif //PIDTEMP
#ifdef PIDTEMPBED
  //static cannot be external:
  static float temp_iState_bed = { 0 };
  static float temp_dState_bed = { 0 };
  static float pTerm_bed;
  static float iTerm_bed;
  static float dTerm_bed;
  //int output;
  static float pid_error_bed;
  static float temp_iState_min_bed;
  static float temp_iState_max_bed;
#else //PIDTEMPBED
	static unsigned long  previous_millis_bed_heater;
#endif //PIDTEMPBED
  static unsigned char soft_pwm[EXTRUDERS];

#ifdef FAN_SOFT_PWM
  static unsigned char soft_pwm_fan;
#endif
#if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
  static unsigned long extruder_autofan_last_check;
#endif  

#if EXTRUDERS > 3
  # error Unsupported number of extruders
#elif EXTRUDERS > 2
  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2, v3 }
#elif EXTRUDERS > 1
  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2 }
#else
  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1 }
#endif

#ifdef PIDTEMP
#ifdef PID_PARAMS_PER_EXTRUDER
  float Kp[EXTRUDERS] = ARRAY_BY_EXTRUDERS(DEFAULT_Kp, DEFAULT_Kp, DEFAULT_Kp);
  float Ki[EXTRUDERS] = ARRAY_BY_EXTRUDERS(DEFAULT_Ki*PID_dT, DEFAULT_Ki*PID_dT, DEFAULT_Ki*PID_dT);
  float Kd[EXTRUDERS] = ARRAY_BY_EXTRUDERS(DEFAULT_Kd / PID_dT, DEFAULT_Kd / PID_dT, DEFAULT_Kd / PID_dT);
  #ifdef PID_ADD_EXTRUSION_RATE
    float Kc[EXTRUDERS] = ARRAY_BY_EXTRUDERS(DEFAULT_Kc, DEFAULT_Kc, DEFAULT_Kc);
  #endif // PID_ADD_EXTRUSION_RATE
#else //PID_PARAMS_PER_EXTRUDER
  float Kp = DEFAULT_Kp;
  float Ki = DEFAULT_Ki * PID_dT;
  float Kd = DEFAULT_Kd / PID_dT;
  #ifdef PID_ADD_EXTRUSION_RATE
    float Kc = DEFAULT_Kc;
  #endif // PID_ADD_EXTRUSION_RATE
#endif // PID_PARAMS_PER_EXTRUDER
#endif //PIDTEMP

// Init min and max temp with extreme values to prevent false errors during startup
static int minttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_LO_TEMP , HEATER_1_RAW_LO_TEMP , HEATER_2_RAW_LO_TEMP );
static int maxttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_HI_TEMP , HEATER_1_RAW_HI_TEMP , HEATER_2_RAW_HI_TEMP );
static int minttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 0, 0, 0 );
static int maxttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 16383, 16383, 16383 );
//static int bed_minttemp_raw = HEATER_BED_RAW_LO_TEMP; /* No bed mintemp error implemented?!? */
#ifdef BED_MAXTEMP
static int bed_maxttemp_raw = HEATER_BED_RAW_HI_TEMP;
#endif

#ifdef TEMP_SENSOR_1_AS_REDUNDANT
  static void *heater_ttbl_map[2] = {(void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE };
  static uint8_t heater_ttbllen_map[2] = { HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN };
#else
  static void *heater_ttbl_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( (void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE, (void *)HEATER_2_TEMPTABLE );
  static uint8_t heater_ttbllen_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN, HEATER_2_TEMPTABLE_LEN );
#endif

static float analog2temp(int raw, uint8_t e);
static float analog2tempBed(int raw);
static void updateTemperaturesFromRawValues();

#ifdef WATCH_TEMP_PERIOD
int watch_start_temp[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0);
unsigned long watchmillis[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0);
#endif //WATCH_TEMP_PERIOD

#ifndef SOFT_PWM_SCALE
#define SOFT_PWM_SCALE 0
#endif

#ifdef FILAMENT_SENSOR
  static int meas_shift_index;  //used to point to a delayed sample in buffer for filament width sensor
#endif

#ifdef HEATER_0_USES_MAX6675
  static int read_max6675();
#endif

//===========================================================================
//=============================   functions      ============================
//===========================================================================

void PID_autotune(float temp, int extruder, int ncycles)
{
  float input = 0.0;
  int cycles=0;
  bool heating = true;

  unsigned long temp_millis = millis();
  unsigned long t1=temp_millis;
  unsigned long t2=temp_millis;
  long t_high = 0;
  long t_low = 0;

  long bias, d;
  float Ku, Tu;
  float Kp, Ki, Kd;
  float max = 0, min = 10000;

#if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
  unsigned long extruder_autofan_last_check = millis();
#endif

  if ((extruder >= EXTRUDERS)
  #if (TEMP_BED_PIN <= -1)
       ||(extruder < 0)
  #endif
       ){
          SERIAL_ECHOLN("PID Autotune failed. Bad extruder number.");
          return;
        }
	
  SERIAL_ECHOLN("PID Autotune start");
  
  disable_heater(); // switch off all heaters.

  if (extruder<0)
  {
     soft_pwm_bed = (MAX_BED_POWER)/2;
     bias = d = (MAX_BED_POWER)/2;
   }
   else
   {
     soft_pwm[extruder] = (PID_MAX)/2;
     bias = d = (PID_MAX)/2;
  }




 for(;;) {

    if(temp_meas_ready == true) { // temp sample ready
      updateTemperaturesFromRawValues();

      input = (extruder<0)?current_temperature_bed:current_temperature[extruder];

      max=max(max,input);
      min=min(min,input);

      #if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
          (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
          (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
      if(millis() - extruder_autofan_last_check > 2500) {
        checkExtruderAutoFans();
        extruder_autofan_last_check = millis();
      }
      #endif

      if(heating == true && input > temp) {
        if(millis() - t2 > 5000) { 
          heating=false;
          if (extruder<0)
            soft_pwm_bed = (bias - d) >> 1;
          else
            soft_pwm[extruder] = (bias - d) >> 1;
          t1=millis();
          t_high=t1 - t2;
          max=temp;
        }
      }
      if(heating == false && input < temp) {
        if(millis() - t1 > 5000) {
          heating=true;
          t2=millis();
          t_low=t2 - t1;
          if(cycles > 0) {
            bias += (d*(t_high - t_low))/(t_low + t_high);
            bias = constrain(bias, 20 ,(extruder<0?(MAX_BED_POWER):(PID_MAX))-20);
            if(bias > (extruder<0?(MAX_BED_POWER):(PID_MAX))/2) d = (extruder<0?(MAX_BED_POWER):(PID_MAX)) - 1 - bias;
            else d = bias;

            SERIAL_PROTOCOLPGM(" bias: "); SERIAL_PROTOCOL(bias);
            SERIAL_PROTOCOLPGM(" d: "); SERIAL_PROTOCOL(d);
            SERIAL_PROTOCOLPGM(" min: "); SERIAL_PROTOCOL(min);
            SERIAL_PROTOCOLPGM(" max: "); SERIAL_PROTOCOLLN(max);
            if(cycles > 2) {
              Ku = (4.0*d)/(3.14159*(max-min)/2.0);
              Tu = ((float)(t_low + t_high)/1000.0);
              SERIAL_PROTOCOLPGM(" Ku: "); SERIAL_PROTOCOL(Ku);
              SERIAL_PROTOCOLPGM(" Tu: "); SERIAL_PROTOCOLLN(Tu);
              Kp = 0.6*Ku;
              Ki = 2*Kp/Tu;
              Kd = Kp*Tu/8;
              SERIAL_PROTOCOLLNPGM(" Classic PID ");
              SERIAL_PROTOCOLPGM(" Kp: "); SERIAL_PROTOCOLLN(Kp);
              SERIAL_PROTOCOLPGM(" Ki: "); SERIAL_PROTOCOLLN(Ki);
              SERIAL_PROTOCOLPGM(" Kd: "); SERIAL_PROTOCOLLN(Kd);
              /*
              Kp = 0.33*Ku;
              Ki = Kp/Tu;
              Kd = Kp*Tu/3;
              SERIAL_PROTOCOLLNPGM(" Some overshoot ");
              SERIAL_PROTOCOLPGM(" Kp: "); SERIAL_PROTOCOLLN(Kp);
              SERIAL_PROTOCOLPGM(" Ki: "); SERIAL_PROTOCOLLN(Ki);
              SERIAL_PROTOCOLPGM(" Kd: "); SERIAL_PROTOCOLLN(Kd);
              Kp = 0.2*Ku;
              Ki = 2*Kp/Tu;
              Kd = Kp*Tu/3;
              SERIAL_PROTOCOLLNPGM(" No overshoot ");
              SERIAL_PROTOCOLPGM(" Kp: "); SERIAL_PROTOCOLLN(Kp);
              SERIAL_PROTOCOLPGM(" Ki: "); SERIAL_PROTOCOLLN(Ki);
              SERIAL_PROTOCOLPGM(" Kd: "); SERIAL_PROTOCOLLN(Kd);
              */
            }
          }
          if (extruder<0)
            soft_pwm_bed = (bias + d) >> 1;
          else
            soft_pwm[extruder] = (bias + d) >> 1;
          cycles++;
          min=temp;
        }
      } 
    }
    if(input > (temp + 20)) {
      SERIAL_PROTOCOLLNPGM("PID Autotune failed! Temperature too high");
      return;
    }
    if(millis() - temp_millis > 2000) {
      int p;
      if (extruder<0){
        p=soft_pwm_bed;       
        SERIAL_PROTOCOLPGM("ok B:");
      }else{
        p=soft_pwm[extruder];       
        SERIAL_PROTOCOLPGM("ok T:");
      }
			
      SERIAL_PROTOCOL(input);   
      SERIAL_PROTOCOLPGM(" @:");
      SERIAL_PROTOCOLLN(p);       

      temp_millis = millis();
    }
    if(((millis() - t1) + (millis() - t2)) > (10L*60L*1000L*2L)) {
      SERIAL_PROTOCOLLNPGM("PID Autotune failed! timeout");
      return;
    }
    if(cycles > ncycles) {
      SERIAL_PROTOCOLLNPGM("PID Autotune finished! Put the last Kp, Ki and Kd constants from above into Configuration.h");
      return;
    }
    lcd_update();
  }
}

void updatePID()
{
#ifdef PIDTEMP
  for(int e = 0; e < EXTRUDERS; e++) { 
     temp_iState_max[e] = PID_INTEGRAL_DRIVE_MAX / PID_PARAM(Ki,e);  
  }
#endif
#ifdef PIDTEMPBED
  temp_iState_max_bed = PID_INTEGRAL_DRIVE_MAX / bedKi;  
#endif
}
  
int getHeaterPower(int heater) {
	if (heater<0)
		return soft_pwm_bed;
  return soft_pwm[heater];
}

#if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
    (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)

  #if defined(FAN_PIN) && FAN_PIN > -1
    #if EXTRUDER_0_AUTO_FAN_PIN == FAN_PIN 
       #error "You cannot set EXTRUDER_0_AUTO_FAN_PIN equal to FAN_PIN"
    #endif
    #if EXTRUDER_1_AUTO_FAN_PIN == FAN_PIN 
       #error "You cannot set EXTRUDER_1_AUTO_FAN_PIN equal to FAN_PIN"
    #endif
    #if EXTRUDER_2_AUTO_FAN_PIN == FAN_PIN 
       #error "You cannot set EXTRUDER_2_AUTO_FAN_PIN equal to FAN_PIN"
    #endif
  #endif 

void setExtruderAutoFanState(int pin, bool state)
{
  unsigned char newFanSpeed = (state != 0) ? EXTRUDER_AUTO_FAN_SPEED : 0;
  // this idiom allows both digital and PWM fan outputs (see M42 handling).
  pinMode(pin, OUTPUT);
  digitalWrite(pin, newFanSpeed);
  analogWrite(pin, newFanSpeed);
}

void checkExtruderAutoFans()
{
  uint8_t fanState = 0;

  // which fan pins need to be turned on?      
  #if defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1
    if (current_temperature[0] > EXTRUDER_AUTO_FAN_TEMPERATURE) 
      fanState |= 1;
  #endif
  #if defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1
    if (current_temperature[1] > EXTRUDER_AUTO_FAN_TEMPERATURE) 
    {
      if (EXTRUDER_1_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN) 
        fanState |= 1;
      else
        fanState |= 2;
    }
  #endif
  #if defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1
    if (current_temperature[2] > EXTRUDER_AUTO_FAN_TEMPERATURE) 
    {
      if (EXTRUDER_2_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN) 
        fanState |= 1;
      else if (EXTRUDER_2_AUTO_FAN_PIN == EXTRUDER_1_AUTO_FAN_PIN) 
        fanState |= 2;
      else
        fanState |= 4;
    }
  #endif
  
  // update extruder auto fan states
  #if defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1
    setExtruderAutoFanState(EXTRUDER_0_AUTO_FAN_PIN, (fanState & 1) != 0);
  #endif 
  #if defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1
    if (EXTRUDER_1_AUTO_FAN_PIN != EXTRUDER_0_AUTO_FAN_PIN) 
      setExtruderAutoFanState(EXTRUDER_1_AUTO_FAN_PIN, (fanState & 2) != 0);
  #endif 
  #if defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1
    if (EXTRUDER_2_AUTO_FAN_PIN != EXTRUDER_0_AUTO_FAN_PIN 
        && EXTRUDER_2_AUTO_FAN_PIN != EXTRUDER_1_AUTO_FAN_PIN)
      setExtruderAutoFanState(EXTRUDER_2_AUTO_FAN_PIN, (fanState & 4) != 0);
  #endif 
}

#endif // any extruder auto fan pins set

void manage_heater()
{
  float pid_input;
  float pid_output;

  if(temp_meas_ready != true)   //better readability
    return; 

  updateTemperaturesFromRawValues();

  #ifdef HEATER_0_USES_MAX6675
    if (current_temperature[0] > 1023 || current_temperature[0] > HEATER_0_MAXTEMP) {
      max_temp_error(0);
    }
    if (current_temperature[0] == 0  || current_temperature[0] < HEATER_0_MINTEMP) {
      min_temp_error(0);
    }
  #endif //HEATER_0_USES_MAX6675

  for(int e = 0; e < EXTRUDERS; e++) 
  {

#if defined (THERMAL_RUNAWAY_PROTECTION_PERIOD) && THERMAL_RUNAWAY_PROTECTION_PERIOD > 0
    thermal_runaway_protection(&thermal_runaway_state_machine[e], &thermal_runaway_timer[e], current_temperature[e], target_temperature[e], e, THERMAL_RUNAWAY_PROTECTION_PERIOD, THERMAL_RUNAWAY_PROTECTION_HYSTERESIS);
  #endif

  #ifdef PIDTEMP
    pid_input = current_temperature[e];

    #ifndef PID_OPENLOOP
        pid_error[e] = target_temperature[e] - pid_input;
        if(pid_error[e] > PID_FUNCTIONAL_RANGE) {
          pid_output = BANG_MAX;
          pid_reset[e] = true;
        }
        else if(pid_error[e] < -PID_FUNCTIONAL_RANGE || target_temperature[e] == 0) {
          pid_output = 0;
          pid_reset[e] = true;
        }
        else {
          if(pid_reset[e] == true) {
            temp_iState[e] = 0.0;
            pid_reset[e] = false;
          }
          pTerm[e] = PID_PARAM(Kp,e) * pid_error[e];
          temp_iState[e] += pid_error[e];
          temp_iState[e] = constrain(temp_iState[e], temp_iState_min[e], temp_iState_max[e]);
          iTerm[e] = PID_PARAM(Ki,e) * temp_iState[e];

          //K1 defined in Configuration.h in the PID settings
          #define K2 (1.0-K1)
          dTerm[e] = (PID_PARAM(Kd,e) * (pid_input - temp_dState[e]))*K2 + (K1 * dTerm[e]);
          pid_output = pTerm[e] + iTerm[e] - dTerm[e];
          if (pid_output > PID_MAX) {
            if (pid_error[e] > 0 )  temp_iState[e] -= pid_error[e]; // conditional un-integration
            pid_output=PID_MAX;
          } else if (pid_output < 0){
            if (pid_error[e] < 0 )  temp_iState[e] -= pid_error[e]; // conditional un-integration
            pid_output=0;
          }
        }
        temp_dState[e] = pid_input;
    #else 
          pid_output = constrain(target_temperature[e], 0, PID_MAX);
    #endif //PID_OPENLOOP
    #ifdef PID_DEBUG
    SERIAL_ECHO_START;
    SERIAL_ECHO(" PID_DEBUG ");
    SERIAL_ECHO(e);
    SERIAL_ECHO(": Input ");
    SERIAL_ECHO(pid_input);
    SERIAL_ECHO(" Output ");
    SERIAL_ECHO(pid_output);
    SERIAL_ECHO(" pTerm ");
    SERIAL_ECHO(pTerm[e]);
    SERIAL_ECHO(" iTerm ");
    SERIAL_ECHO(iTerm[e]);
    SERIAL_ECHO(" dTerm ");
    SERIAL_ECHOLN(dTerm[e]);
    #endif //PID_DEBUG
  #else /* PID off */
    pid_output = 0;
    if(current_temperature[e] < target_temperature[e]) {
      pid_output = PID_MAX;
    }
  #endif

    // Check if temperature is within the correct range
    if((current_temperature[e] > minttemp[e]) && (current_temperature[e] < maxttemp[e])) 
    {
      soft_pwm[e] = (int)pid_output >> 1;
    }
    else {
      soft_pwm[e] = 0;
    }

    #ifdef WATCH_TEMP_PERIOD
    if(watchmillis[e] && millis() - watchmillis[e] > WATCH_TEMP_PERIOD)
    {
        if(degHotend(e) < watch_start_temp[e] + WATCH_TEMP_INCREASE)
        {
            setTargetHotend(0, e);
            LCD_MESSAGEPGM("Heating failed");
            SERIAL_ECHO_START;
            SERIAL_ECHOLN("Heating failed");
        }else{
            watchmillis[e] = 0;
        }
    }
    #endif
    #ifdef TEMP_SENSOR_1_AS_REDUNDANT
      if(fabs(current_temperature[0] - redundant_temperature) > MAX_REDUNDANT_TEMP_SENSOR_DIFF) {
        disable_heater();
        if(IsStopped() == false) {
          SERIAL_ERROR_START;
          SERIAL_ERRORLNPGM("Extruder switched off. Temperature difference between temp sensors is too high !");
          LCD_ALERTMESSAGEPGM("Err: REDUNDANT TEMP ERROR");
        }
        #ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
          Stop();
        #endif
      }
    #endif
  } // End extruder for loop

  #if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
      (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
      (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
  if(millis() - extruder_autofan_last_check > 2500)  // only need to check fan state very infrequently
  {
    checkExtruderAutoFans();
    extruder_autofan_last_check = millis();
  }  
  #endif       
  
  #ifndef PIDTEMPBED
  if(millis() - previous_millis_bed_heater < BED_CHECK_INTERVAL)
    return;
  previous_millis_bed_heater = millis();
  #endif

  #if TEMP_SENSOR_BED != 0
  
    #if defined(THERMAL_RUNAWAY_PROTECTION_BED_PERIOD) && THERMAL_RUNAWAY_PROTECTION_BED_PERIOD > 0
      thermal_runaway_protection(&thermal_runaway_bed_state_machine, &thermal_runaway_bed_timer, current_temperature_bed, target_temperature_bed, 9, THERMAL_RUNAWAY_PROTECTION_BED_PERIOD, THERMAL_RUNAWAY_PROTECTION_BED_HYSTERESIS);
    #endif

  #ifdef PIDTEMPBED
    pid_input = current_temperature_bed;

    #ifndef PID_OPENLOOP
		  pid_error_bed = target_temperature_bed - pid_input;
		  pTerm_bed = bedKp * pid_error_bed;
		  temp_iState_bed += pid_error_bed;
		  temp_iState_bed = constrain(temp_iState_bed, temp_iState_min_bed, temp_iState_max_bed);
		  iTerm_bed = bedKi * temp_iState_bed;

		  //K1 defined in Configuration.h in the PID settings
		  #define K2 (1.0-K1)
		  dTerm_bed= (bedKd * (pid_input - temp_dState_bed))*K2 + (K1 * dTerm_bed);
		  temp_dState_bed = pid_input;

		  pid_output = pTerm_bed + iTerm_bed - dTerm_bed;
          	  if (pid_output > MAX_BED_POWER) {
            	    if (pid_error_bed > 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
                    pid_output=MAX_BED_POWER;
          	  } else if (pid_output < 0){
            	    if (pid_error_bed < 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
                    pid_output=0;
                  }

    #else 
      pid_output = constrain(target_temperature_bed, 0, MAX_BED_POWER);
    #endif //PID_OPENLOOP

	  if((current_temperature_bed > BED_MINTEMP) && (current_temperature_bed < BED_MAXTEMP)) 
	  {
	    soft_pwm_bed = (int)pid_output >> 1;
	  }
	  else {
	    soft_pwm_bed = 0;
	  }

    #elif !defined(BED_LIMIT_SWITCHING)
      // Check if temperature is within the correct range
      if((current_temperature_bed > BED_MINTEMP) && (current_temperature_bed < BED_MAXTEMP))
      {
        if(current_temperature_bed >= target_temperature_bed)
        {
          soft_pwm_bed = 0;
        }
        else 
        {
          soft_pwm_bed = MAX_BED_POWER>>1;
        }
      }
      else
      {
        soft_pwm_bed = 0;
        WRITE(HEATER_BED_PIN,LOW);
      }
    #else //#ifdef BED_LIMIT_SWITCHING
      // Check if temperature is within the correct band
      if((current_temperature_bed > BED_MINTEMP) && (current_temperature_bed < BED_MAXTEMP))
      {
        if(current_temperature_bed > target_temperature_bed + BED_HYSTERESIS)
        {
          soft_pwm_bed = 0;
        }
        else if(current_temperature_bed <= target_temperature_bed - BED_HYSTERESIS)
        {
          soft_pwm_bed = MAX_BED_POWER>>1;
        }
      }
      else
      {
        soft_pwm_bed = 0;
        WRITE(HEATER_BED_PIN,LOW);
      }
    #endif
  #endif
  
//code for controlling the extruder rate based on the width sensor 
#ifdef FILAMENT_SENSOR
  if(filament_sensor) 
	{
	meas_shift_index=delay_index1-meas_delay_cm;
		  if(meas_shift_index<0)
			  meas_shift_index = meas_shift_index + (MAX_MEASUREMENT_DELAY+1);  //loop around buffer if needed
		  
		  //get the delayed info and add 100 to reconstitute to a percent of the nominal filament diameter
		  //then square it to get an area
		  
		  if(meas_shift_index<0)
			  meas_shift_index=0;
		  else if (meas_shift_index>MAX_MEASUREMENT_DELAY)
			  meas_shift_index=MAX_MEASUREMENT_DELAY;
		  
		     volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM] = pow((float)(100+measurement_delay[meas_shift_index])/100.0,2);
		     if (volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM] <0.01)
		    	 volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM]=0.01;
	}
#endif
}

#define PGM_RD_W(x)   (short)pgm_read_word(&x)
// Derived from RepRap FiveD extruder::getTemperature()
// For hot end temperature measurement.
static float analog2temp(int raw, uint8_t e) {
#ifdef TEMP_SENSOR_1_AS_REDUNDANT
  if(e > EXTRUDERS)
#else
  if(e >= EXTRUDERS)
#endif
  {
      SERIAL_ERROR_START;
      SERIAL_ERROR((int)e);
      SERIAL_ERRORLNPGM(" - Invalid extruder number !");
      kill();
      return 0.0;
  } 
  #ifdef HEATER_0_USES_MAX6675
    if (e == 0)
    {
      return 0.25 * raw;
    }
  #endif

  if(heater_ttbl_map[e] != NULL)
  {
    float celsius = 0;
    uint8_t i;
    short (*tt)[][2] = (short (*)[][2])(heater_ttbl_map[e]);

    for (i=1; i<heater_ttbllen_map[e]; i++)
    {
      if (PGM_RD_W((*tt)[i][0]) > raw)
      {
        celsius = PGM_RD_W((*tt)[i-1][1]) + 
          (raw - PGM_RD_W((*tt)[i-1][0])) * 
          (float)(PGM_RD_W((*tt)[i][1]) - PGM_RD_W((*tt)[i-1][1])) /
          (float)(PGM_RD_W((*tt)[i][0]) - PGM_RD_W((*tt)[i-1][0]));
        break;
      }
    }

    // Overflow: Set to last value in the table
    if (i == heater_ttbllen_map[e]) celsius = PGM_RD_W((*tt)[i-1][1]);

    return celsius;
  }
  return ((raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR) * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET;
}

// Derived from RepRap FiveD extruder::getTemperature()
// For bed temperature measurement.
static float analog2tempBed(int raw) {
  #ifdef BED_USES_THERMISTOR
    float celsius = 0;
    byte i;

    for (i=1; i<BEDTEMPTABLE_LEN; i++)
    {
      if (PGM_RD_W(BEDTEMPTABLE[i][0]) > raw)
      {
        celsius  = PGM_RD_W(BEDTEMPTABLE[i-1][1]) + 
          (raw - PGM_RD_W(BEDTEMPTABLE[i-1][0])) * 
          (float)(PGM_RD_W(BEDTEMPTABLE[i][1]) - PGM_RD_W(BEDTEMPTABLE[i-1][1])) /
          (float)(PGM_RD_W(BEDTEMPTABLE[i][0]) - PGM_RD_W(BEDTEMPTABLE[i-1][0]));
        break;
      }
    }

    // Overflow: Set to last value in the table
    if (i == BEDTEMPTABLE_LEN) celsius = PGM_RD_W(BEDTEMPTABLE[i-1][1]);

    return celsius;
  #elif defined BED_USES_AD595
    return ((raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR) * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET;
  #else
    return 0;
  #endif
}

/* Called to get the raw values into the the actual temperatures. The raw values are created in interrupt context,
    and this function is called from normal context as it is too slow to run in interrupts and will block the stepper routine otherwise */
static void updateTemperaturesFromRawValues()
{
    #ifdef HEATER_0_USES_MAX6675
        current_temperature_raw[0] = read_max6675();
    #endif
    for(uint8_t e=0;e<EXTRUDERS;e++)
    {
        current_temperature[e] = analog2temp(current_temperature_raw[e], e);
    }
    current_temperature_bed = analog2tempBed(current_temperature_bed_raw);
    #ifdef TEMP_SENSOR_1_AS_REDUNDANT
      redundant_temperature = analog2temp(redundant_temperature_raw, 1);
    #endif
    #if defined (FILAMENT_SENSOR) && (FILWIDTH_PIN > -1)    //check if a sensor is supported 
      filament_width_meas = analog2widthFil();
    #endif  
    //Reset the watchdog after we know we have a temperature measurement.
    watchdog_reset();

    CRITICAL_SECTION_START;
    temp_meas_ready = false;
    CRITICAL_SECTION_END;
}


// For converting raw Filament Width to milimeters 
#ifdef FILAMENT_SENSOR
float analog2widthFil() { 
return current_raw_filwidth/16383.0*5.0; 
//return current_raw_filwidth; 
} 
 
// For converting raw Filament Width to a ratio 
int widthFil_to_size_ratio() { 
 
float temp; 
      
temp=filament_width_meas;
if(filament_width_meas<MEASURED_LOWER_LIMIT)
	temp=filament_width_nominal;  //assume sensor cut out
else if (filament_width_meas>MEASURED_UPPER_LIMIT)
	temp= MEASURED_UPPER_LIMIT;


return(filament_width_nominal/temp*100); 


} 
#endif





void tp_init()
{
#if MB(RUMBA) && ((TEMP_SENSOR_0==-1)||(TEMP_SENSOR_1==-1)||(TEMP_SENSOR_2==-1)||(TEMP_SENSOR_BED==-1))
  //disable RUMBA JTAG in case the thermocouple extension is plugged on top of JTAG connector
  MCUCR=(1<<JTD); 
  MCUCR=(1<<JTD);
#endif
  
  // Finish init of mult extruder arrays 
  for(int e = 0; e < EXTRUDERS; e++) {
    // populate with the first value 
    maxttemp[e] = maxttemp[0];
#ifdef PIDTEMP
    temp_iState_min[e] = 0.0;
    temp_iState_max[e] = PID_INTEGRAL_DRIVE_MAX / PID_PARAM(Ki,e);
#endif //PIDTEMP
#ifdef PIDTEMPBED
    temp_iState_min_bed = 0.0;
    temp_iState_max_bed = PID_INTEGRAL_DRIVE_MAX / bedKi;
#endif //PIDTEMPBED
  }

  #if defined(HEATER_0_PIN) && (HEATER_0_PIN > -1) 
    SET_OUTPUT(HEATER_0_PIN);
  #endif  
  #if defined(HEATER_1_PIN) && (HEATER_1_PIN > -1) 
    SET_OUTPUT(HEATER_1_PIN);
  #endif
  #if defined(HEATER_2_PIN) && (HEATER_2_PIN > -1) 
    SET_OUTPUT(HEATER_2_PIN);
  #endif  
  #if defined(HEATER_BED_PIN) && (HEATER_BED_PIN > -1) 
    SET_OUTPUT(HEATER_BED_PIN);
  #endif  
  #if defined(FAN_PIN) && (FAN_PIN > -1) 
    SET_OUTPUT(FAN_PIN);
    #ifdef FAST_PWM_FAN
    setPwmFrequency(FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
    #endif
    #ifdef FAN_SOFT_PWM
    soft_pwm_fan = fanSpeedSoftPwm / 2;
    #endif
  #endif  

  #ifdef HEATER_0_USES_MAX6675

    #ifndef SDSUPPORT
      SET_OUTPUT(SCK_PIN);
      WRITE(SCK_PIN,0);
    
      SET_OUTPUT(MOSI_PIN);
      WRITE(MOSI_PIN,1);
    
      SET_INPUT(MISO_PIN);
      WRITE(MISO_PIN,1);
    #else
      pinMode(SS_PIN, OUTPUT);
      digitalWrite(SS_PIN, HIGH);
    #endif
    
    SET_OUTPUT(MAX6675_SS);
    WRITE(MAX6675_SS,1);

  #endif //HEATER_0_USES_MAX6675

  // Set analog inputs
  ADCSRA = 1<<ADEN | 1<<ADSC | 1<<ADIF | 0x07;
  DIDR0 = 0;
  #ifdef DIDR2
    DIDR2 = 0;
  #endif
  #if defined(TEMP_0_PIN) && (TEMP_0_PIN > -1)
    #if TEMP_0_PIN < 8
       DIDR0 |= 1 << TEMP_0_PIN; 
    #else
       DIDR2 |= 1<<(TEMP_0_PIN - 8); 
    #endif
  #endif
  #if defined(TEMP_1_PIN) && (TEMP_1_PIN > -1)
    #if TEMP_1_PIN < 8
       DIDR0 |= 1<<TEMP_1_PIN; 
    #else
       DIDR2 |= 1<<(TEMP_1_PIN - 8); 
    #endif
  #endif
  #if defined(TEMP_2_PIN) && (TEMP_2_PIN > -1)
    #if TEMP_2_PIN < 8
       DIDR0 |= 1 << TEMP_2_PIN; 
    #else
       DIDR2 |= 1<<(TEMP_2_PIN - 8); 
    #endif
  #endif
  #if defined(TEMP_BED_PIN) && (TEMP_BED_PIN > -1)
    #if TEMP_BED_PIN < 8
       DIDR0 |= 1<<TEMP_BED_PIN; 
    #else
       DIDR2 |= 1<<(TEMP_BED_PIN - 8); 
    #endif
  #endif
  
  //Added for Filament Sensor 
  #ifdef FILAMENT_SENSOR
   #if defined(FILWIDTH_PIN) && (FILWIDTH_PIN > -1) 
	#if FILWIDTH_PIN < 8 
       	   DIDR0 |= 1<<FILWIDTH_PIN;  
	#else 
       	   DIDR2 |= 1<<(FILWIDTH_PIN - 8);  
	#endif 
   #endif
  #endif
  
  // Use timer0 for temperature measurement
  // Interleave temperature interrupt with millies interrupt
  OCR0B = 128;
  TIMSK0 |= (1<<OCIE0B);  
  
  // Wait for temperature measurement to settle
  delay(250);

#ifdef HEATER_0_MINTEMP
  minttemp[0] = HEATER_0_MINTEMP;
  while(analog2temp(minttemp_raw[0], 0) < HEATER_0_MINTEMP) {
#if HEATER_0_RAW_LO_TEMP < HEATER_0_RAW_HI_TEMP
    minttemp_raw[0] += OVERSAMPLENR;
#else
    minttemp_raw[0] -= OVERSAMPLENR;
#endif
  }
#endif //MINTEMP
#ifdef HEATER_0_MAXTEMP
  maxttemp[0] = HEATER_0_MAXTEMP;
  while(analog2temp(maxttemp_raw[0], 0) > HEATER_0_MAXTEMP) {
#if HEATER_0_RAW_LO_TEMP < HEATER_0_RAW_HI_TEMP
    maxttemp_raw[0] -= OVERSAMPLENR;
#else
    maxttemp_raw[0] += OVERSAMPLENR;
#endif
  }
#endif //MAXTEMP

#if (EXTRUDERS > 1) && defined(HEATER_1_MINTEMP)
  minttemp[1] = HEATER_1_MINTEMP;
  while(analog2temp(minttemp_raw[1], 1) < HEATER_1_MINTEMP) {
#if HEATER_1_RAW_LO_TEMP < HEATER_1_RAW_HI_TEMP
    minttemp_raw[1] += OVERSAMPLENR;
#else
    minttemp_raw[1] -= OVERSAMPLENR;
#endif
  }
#endif // MINTEMP 1
#if (EXTRUDERS > 1) && defined(HEATER_1_MAXTEMP)
  maxttemp[1] = HEATER_1_MAXTEMP;
  while(analog2temp(maxttemp_raw[1], 1) > HEATER_1_MAXTEMP) {
#if HEATER_1_RAW_LO_TEMP < HEATER_1_RAW_HI_TEMP
    maxttemp_raw[1] -= OVERSAMPLENR;
#else
    maxttemp_raw[1] += OVERSAMPLENR;
#endif
  }
#endif //MAXTEMP 1

#if (EXTRUDERS > 2) && defined(HEATER_2_MINTEMP)
  minttemp[2] = HEATER_2_MINTEMP;
  while(analog2temp(minttemp_raw[2], 2) < HEATER_2_MINTEMP) {
#if HEATER_2_RAW_LO_TEMP < HEATER_2_RAW_HI_TEMP
    minttemp_raw[2] += OVERSAMPLENR;
#else
    minttemp_raw[2] -= OVERSAMPLENR;
#endif
  }
#endif //MINTEMP 2
#if (EXTRUDERS > 2) && defined(HEATER_2_MAXTEMP)
  maxttemp[2] = HEATER_2_MAXTEMP;
  while(analog2temp(maxttemp_raw[2], 2) > HEATER_2_MAXTEMP) {
#if HEATER_2_RAW_LO_TEMP < HEATER_2_RAW_HI_TEMP
    maxttemp_raw[2] -= OVERSAMPLENR;
#else
    maxttemp_raw[2] += OVERSAMPLENR;
#endif
  }
#endif //MAXTEMP 2

#ifdef BED_MINTEMP
  /* No bed MINTEMP error implemented?!? */ /*
  while(analog2tempBed(bed_minttemp_raw) < BED_MINTEMP) {
#if HEATER_BED_RAW_LO_TEMP < HEATER_BED_RAW_HI_TEMP
    bed_minttemp_raw += OVERSAMPLENR;
#else
    bed_minttemp_raw -= OVERSAMPLENR;
#endif
  }
  */
#endif //BED_MINTEMP
#ifdef BED_MAXTEMP
  while(analog2tempBed(bed_maxttemp_raw) > BED_MAXTEMP) {
#if HEATER_BED_RAW_LO_TEMP < HEATER_BED_RAW_HI_TEMP
    bed_maxttemp_raw -= OVERSAMPLENR;
#else
    bed_maxttemp_raw += OVERSAMPLENR;
#endif
  }
#endif //BED_MAXTEMP
}

void setWatch() 
{  
#ifdef WATCH_TEMP_PERIOD
  for (int e = 0; e < EXTRUDERS; e++)
  {
    if(degHotend(e) < degTargetHotend(e) - (WATCH_TEMP_INCREASE * 2))
    {
      watch_start_temp[e] = degHotend(e);
      watchmillis[e] = millis();
    } 
  }
#endif 
}

#if defined (THERMAL_RUNAWAY_PROTECTION_PERIOD) && THERMAL_RUNAWAY_PROTECTION_PERIOD > 0
void thermal_runaway_protection(int *state, unsigned long *timer, float temperature, float target_temperature, int heater_id, int period_seconds, int hysteresis_degc)
{
/*
      SERIAL_ECHO_START;
      SERIAL_ECHO("Thermal Thermal Runaway Running. Heater ID:");
      SERIAL_ECHO(heater_id);
      SERIAL_ECHO(" ;  State:");
      SERIAL_ECHO(*state);
      SERIAL_ECHO(" ;  Timer:");
      SERIAL_ECHO(*timer);
      SERIAL_ECHO(" ;  Temperature:");
      SERIAL_ECHO(temperature);
      SERIAL_ECHO(" ;  Target Temp:");
      SERIAL_ECHO(target_temperature);
      SERIAL_ECHOLN("");    
*/
  if ((target_temperature == 0) || thermal_runaway)
  {
    *state = 0;
    *timer = 0;
    return;
  }
  switch (*state)
  {
    case 0: // "Heater Inactive" state
      if (target_temperature > 0) *state = 1;
      break;
    case 1: // "First Heating" state
      if (temperature >= target_temperature) *state = 2;
      break;
    case 2: // "Temperature Stable" state
      if (temperature >= (target_temperature - hysteresis_degc))
      {
        *timer = millis();
      } 
      else if ( (millis() - *timer) > ((unsigned long) period_seconds) * 1000)
      {
        SERIAL_ERROR_START;
        SERIAL_ERRORLNPGM("Thermal Runaway, system stopped! Heater_ID: ");
        SERIAL_ERRORLN((int)heater_id);
        LCD_ALERTMESSAGEPGM("THERMAL RUNAWAY");
        thermal_runaway = true;
        while(1)
        {
          disable_heater();
          disable_x();
          disable_y();
          disable_z();
          disable_e0();
          disable_e1();
          disable_e2();
          manage_heater();
          lcd_update();
        }
      }
      break;
  }
}
#endif

void disable_heater()
{
  for(int i=0;i<EXTRUDERS;i++)
    setTargetHotend(0,i);
  setTargetBed(0);
  #if defined(TEMP_0_PIN) && TEMP_0_PIN > -1
  target_temperature[0]=0;
  soft_pwm[0]=0;
   #if defined(HEATER_0_PIN) && HEATER_0_PIN > -1  
     WRITE(HEATER_0_PIN,LOW);
   #endif
  #endif
     
  #if defined(TEMP_1_PIN) && TEMP_1_PIN > -1 && EXTRUDERS > 1
    target_temperature[1]=0;
    soft_pwm[1]=0;
    #if defined(HEATER_1_PIN) && HEATER_1_PIN > -1 
      WRITE(HEATER_1_PIN,LOW);
    #endif
  #endif
      
  #if defined(TEMP_2_PIN) && TEMP_2_PIN > -1 && EXTRUDERS > 2
    target_temperature[2]=0;
    soft_pwm[2]=0;
    #if defined(HEATER_2_PIN) && HEATER_2_PIN > -1  
      WRITE(HEATER_2_PIN,LOW);
    #endif
  #endif 

  #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
    target_temperature_bed=0;
    soft_pwm_bed=0;
    #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1  
      WRITE(HEATER_BED_PIN,LOW);
    #endif
  #endif 
}

void max_temp_error(uint8_t e) {
  disable_heater();
  if(IsStopped() == false) {
    SERIAL_ERROR_START;
    SERIAL_ERRORLN((int)e);
    SERIAL_ERRORLNPGM(": Extruder switched off. MAXTEMP triggered !");
    LCD_ALERTMESSAGEPGM("Err: MAXTEMP");
  }
  #ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
  Stop();
  #endif
}

void min_temp_error(uint8_t e) {
  disable_heater();
  if(IsStopped() == false) {
    SERIAL_ERROR_START;
    SERIAL_ERRORLN((int)e);
    SERIAL_ERRORLNPGM(": Extruder switched off. MINTEMP triggered !");
    LCD_ALERTMESSAGEPGM("Err: MINTEMP");
  }
  #ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
  Stop();
  #endif
}

void bed_max_temp_error(void) {
#if HEATER_BED_PIN > -1
  WRITE(HEATER_BED_PIN, 0);
#endif
  if(IsStopped() == false) {
    SERIAL_ERROR_START;
    SERIAL_ERRORLNPGM("Temperature heated bed switched off. MAXTEMP triggered !!");
    LCD_ALERTMESSAGEPGM("Err: MAXTEMP BED");
  }
  #ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
  Stop();
  #endif
}

#ifdef HEATER_0_USES_MAX6675
#define MAX6675_HEAT_INTERVAL 250
long max6675_previous_millis = MAX6675_HEAT_INTERVAL;
int max6675_temp = 2000;

static int read_max6675()
{
  if (millis() - max6675_previous_millis < MAX6675_HEAT_INTERVAL) 
    return max6675_temp;
  
  max6675_previous_millis = millis();
  max6675_temp = 0;
    
  #ifdef PRR
    PRR &= ~(1<<PRSPI);
  #elif defined(PRR0)
    PRR0 &= ~(1<<PRSPI);
  #endif
  
  SPCR = (1<<MSTR) | (1<<SPE) | (1<<SPR0);
  
  // enable TT_MAX6675
  WRITE(MAX6675_SS, 0);
  
  // ensure 100ns delay - a bit extra is fine
  asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
  asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
  
  // read MSB
  SPDR = 0;
  for (;(SPSR & (1<<SPIF)) == 0;);
  max6675_temp = SPDR;
  max6675_temp <<= 8;
  
  // read LSB
  SPDR = 0;
  for (;(SPSR & (1<<SPIF)) == 0;);
  max6675_temp |= SPDR;
  
  // disable TT_MAX6675
  WRITE(MAX6675_SS, 1);

  if (max6675_temp & 4)
  {
    // thermocouple open
    max6675_temp = 4000;
  }
  else 
  {
    max6675_temp = max6675_temp >> 3;
  }

  return max6675_temp;
}

#endif //HEATER_0_USES_MAX6675


// Timer 0 is shared with millies
ISR(TIMER0_COMPB_vect)
{
  //these variables are only accesible from the ISR, but static, so they don't lose their value
  static unsigned char temp_count = 0;
  static unsigned long raw_temp_0_value = 0;
  static unsigned long raw_temp_1_value = 0;
  static unsigned long raw_temp_2_value = 0;
  static unsigned long raw_temp_bed_value = 0;
  static unsigned char temp_state = 10;
  static unsigned char pwm_count = (1 << SOFT_PWM_SCALE);
  static unsigned char soft_pwm_0;
#ifdef SLOW_PWM_HEATERS
  static unsigned char slow_pwm_count = 0;
  static unsigned char state_heater_0 = 0;
  static unsigned char state_timer_heater_0 = 0;
#endif 
#if (EXTRUDERS > 1) || defined(HEATERS_PARALLEL)
  static unsigned char soft_pwm_1;
#ifdef SLOW_PWM_HEATERS
  static unsigned char state_heater_1 = 0;
  static unsigned char state_timer_heater_1 = 0;
#endif 
#endif
#if EXTRUDERS > 2
  static unsigned char soft_pwm_2;
#ifdef SLOW_PWM_HEATERS
  static unsigned char state_heater_2 = 0;
  static unsigned char state_timer_heater_2 = 0;
#endif 
#endif
#if HEATER_BED_PIN > -1
  static unsigned char soft_pwm_b;
#ifdef SLOW_PWM_HEATERS
  static unsigned char state_heater_b = 0;
  static unsigned char state_timer_heater_b = 0;
#endif 
#endif
  
#if defined(FILWIDTH_PIN) &&(FILWIDTH_PIN > -1)
  static unsigned long raw_filwidth_value = 0;  //added for filament width sensor
#endif
  
#ifndef SLOW_PWM_HEATERS
  /*
   * standard PWM modulation
   */
  if(pwm_count == 0){
    soft_pwm_0 = soft_pwm[0];
    if(soft_pwm_0 > 0) { 
      WRITE(HEATER_0_PIN,1);
#ifdef HEATERS_PARALLEL
      WRITE(HEATER_1_PIN,1);
#endif
    } else WRITE(HEATER_0_PIN,0);
    
#if EXTRUDERS > 1
    soft_pwm_1 = soft_pwm[1];
    if(soft_pwm_1 > 0) WRITE(HEATER_1_PIN,1); else WRITE(HEATER_1_PIN,0);
#endif
#if EXTRUDERS > 2
    soft_pwm_2 = soft_pwm[2];
    if(soft_pwm_2 > 0) WRITE(HEATER_2_PIN,1); else WRITE(HEATER_2_PIN,0);
#endif
#if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
    soft_pwm_b = soft_pwm_bed;
    if(soft_pwm_b > 0) WRITE(HEATER_BED_PIN,1); else WRITE(HEATER_BED_PIN,0);
#endif
#ifdef FAN_SOFT_PWM
    soft_pwm_fan = fanSpeedSoftPwm / 2;
    if(soft_pwm_fan > 0) WRITE(FAN_PIN,1); else WRITE(FAN_PIN,0);
#endif
  }
  if(soft_pwm_0 < pwm_count) { 
    WRITE(HEATER_0_PIN,0);
#ifdef HEATERS_PARALLEL
    WRITE(HEATER_1_PIN,0);
#endif
  }
#if EXTRUDERS > 1
  if(soft_pwm_1 < pwm_count) WRITE(HEATER_1_PIN,0);
#endif
#if EXTRUDERS > 2
  if(soft_pwm_2 < pwm_count) WRITE(HEATER_2_PIN,0);
#endif
#if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
  if(soft_pwm_b < pwm_count) WRITE(HEATER_BED_PIN,0);
#endif
#ifdef FAN_SOFT_PWM
  if(soft_pwm_fan < pwm_count) WRITE(FAN_PIN,0);
#endif
  
  pwm_count += (1 << SOFT_PWM_SCALE);
  pwm_count &= 0x7f;
  
#else //ifndef SLOW_PWM_HEATERS
  /*
   * SLOW PWM HEATERS
   *
   * for heaters drived by relay
   */
#ifndef MIN_STATE_TIME
#define MIN_STATE_TIME 16 // MIN_STATE_TIME * 65.5 = time in milliseconds
#endif
  if (slow_pwm_count == 0) {
    // EXTRUDER 0 
    soft_pwm_0 = soft_pwm[0];
    if (soft_pwm_0 > 0) {
      // turn ON heather only if the minimum time is up 
      if (state_timer_heater_0 == 0) { 
	// if change state set timer 
	if (state_heater_0 == 0) {
	  state_timer_heater_0 = MIN_STATE_TIME;
	}
	state_heater_0 = 1;
	WRITE(HEATER_0_PIN, 1);
#ifdef HEATERS_PARALLEL
	WRITE(HEATER_1_PIN, 1);
#endif
      }
    } else {
      // turn OFF heather only if the minimum time is up 
      if (state_timer_heater_0 == 0) {
	// if change state set timer 
	if (state_heater_0 == 1) {
	  state_timer_heater_0 = MIN_STATE_TIME;
	}
	state_heater_0 = 0;
	WRITE(HEATER_0_PIN, 0);
#ifdef HEATERS_PARALLEL
	WRITE(HEATER_1_PIN, 0);
#endif
      }
    }
    
#if EXTRUDERS > 1
    // EXTRUDER 1
    soft_pwm_1 = soft_pwm[1];
    if (soft_pwm_1 > 0) {
      // turn ON heather only if the minimum time is up 
      if (state_timer_heater_1 == 0) { 
	// if change state set timer 
	if (state_heater_1 == 0) {
	  state_timer_heater_1 = MIN_STATE_TIME;
	}
	state_heater_1 = 1;
	WRITE(HEATER_1_PIN, 1);
      }
    } else {
      // turn OFF heather only if the minimum time is up 
      if (state_timer_heater_1 == 0) {
	// if change state set timer 
	if (state_heater_1 == 1) {
	  state_timer_heater_1 = MIN_STATE_TIME;
	}
	state_heater_1 = 0;
	WRITE(HEATER_1_PIN, 0);
      }
    }
#endif
    
#if EXTRUDERS > 2
    // EXTRUDER 2
    soft_pwm_2 = soft_pwm[2];
    if (soft_pwm_2 > 0) {
      // turn ON heather only if the minimum time is up 
      if (state_timer_heater_2 == 0) { 
	// if change state set timer 
	if (state_heater_2 == 0) {
	  state_timer_heater_2 = MIN_STATE_TIME;
	}
	state_heater_2 = 1;
	WRITE(HEATER_2_PIN, 1);
      }
    } else {
      // turn OFF heather only if the minimum time is up 
      if (state_timer_heater_2 == 0) {
	// if change state set timer 
	if (state_heater_2 == 1) {
	  state_timer_heater_2 = MIN_STATE_TIME;
	}
	state_heater_2 = 0;
	WRITE(HEATER_2_PIN, 0);
      }
    }
#endif
    
#if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
    // BED
    soft_pwm_b = soft_pwm_bed;
    if (soft_pwm_b > 0) {
      // turn ON heather only if the minimum time is up 
      if (state_timer_heater_b == 0) { 
	// if change state set timer 
	if (state_heater_b == 0) {
	  state_timer_heater_b = MIN_STATE_TIME;
	}
	state_heater_b = 1;
	WRITE(HEATER_BED_PIN, 1);
      }
    } else {
      // turn OFF heather only if the minimum time is up 
      if (state_timer_heater_b == 0) {
	// if change state set timer 
	if (state_heater_b == 1) {
	  state_timer_heater_b = MIN_STATE_TIME;
	}
	state_heater_b = 0;
	WRITE(HEATER_BED_PIN, 0);
      }
    }
#endif
  } // if (slow_pwm_count == 0)
  
  // EXTRUDER 0 
  if (soft_pwm_0 < slow_pwm_count) {
    // turn OFF heather only if the minimum time is up 
    if (state_timer_heater_0 == 0) { 
      // if change state set timer 
      if (state_heater_0 == 1) {
	state_timer_heater_0 = MIN_STATE_TIME;
      }
      state_heater_0 = 0;
      WRITE(HEATER_0_PIN, 0);
#ifdef HEATERS_PARALLEL
      WRITE(HEATER_1_PIN, 0);
#endif
    }
  }
    
#if EXTRUDERS > 1
  // EXTRUDER 1 
  if (soft_pwm_1 < slow_pwm_count) {
    // turn OFF heather only if the minimum time is up 
    if (state_timer_heater_1 == 0) { 
      // if change state set timer 
      if (state_heater_1 == 1) {
	state_timer_heater_1 = MIN_STATE_TIME;
      }
      state_heater_1 = 0;
      WRITE(HEATER_1_PIN, 0);
    }
  }
#endif
  
#if EXTRUDERS > 2
  // EXTRUDER 2
  if (soft_pwm_2 < slow_pwm_count) {
    // turn OFF heather only if the minimum time is up 
    if (state_timer_heater_2 == 0) { 
      // if change state set timer 
      if (state_heater_2 == 1) {
	state_timer_heater_2 = MIN_STATE_TIME;
      }
      state_heater_2 = 0;
      WRITE(HEATER_2_PIN, 0);
    }
  }
#endif
  
#if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
  // BED
  if (soft_pwm_b < slow_pwm_count) {
    // turn OFF heather only if the minimum time is up 
    if (state_timer_heater_b == 0) { 
      // if change state set timer 
      if (state_heater_b == 1) {
	state_timer_heater_b = MIN_STATE_TIME;
      }
      state_heater_b = 0;
      WRITE(HEATER_BED_PIN, 0);
    }
  }
#endif
  
#ifdef FAN_SOFT_PWM
  if (pwm_count == 0){
    soft_pwm_fan = fanSpeedSoftPwm / 2;
    if (soft_pwm_fan > 0) WRITE(FAN_PIN,1); else WRITE(FAN_PIN,0);
  }
  if (soft_pwm_fan < pwm_count) WRITE(FAN_PIN,0);
#endif
  
  pwm_count += (1 << SOFT_PWM_SCALE);
  pwm_count &= 0x7f;
  
  // increment slow_pwm_count only every 64 pwm_count circa 65.5ms
  if ((pwm_count % 64) == 0) {
    slow_pwm_count++;
    slow_pwm_count &= 0x7f;
    
    // Extruder 0
    if (state_timer_heater_0 > 0) {
      state_timer_heater_0--;
    } 
  
#if EXTRUDERS > 1
    // Extruder 1
    if (state_timer_heater_1 > 0) 
      state_timer_heater_1--;
#endif
    
#if EXTRUDERS > 2
    // Extruder 2
    if (state_timer_heater_2 > 0) 
      state_timer_heater_2--;
#endif
    
#if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
    // Bed   
    if (state_timer_heater_b > 0) 
      state_timer_heater_b--;
#endif
  } //if ((pwm_count % 64) == 0) {
  
#endif //ifndef SLOW_PWM_HEATERS
  
  switch(temp_state) {
    case 0: // Prepare TEMP_0
      #if defined(TEMP_0_PIN) && (TEMP_0_PIN > -1)
        #if TEMP_0_PIN > 7
          ADCSRB = 1<<MUX5;
        #else
          ADCSRB = 0;
        #endif
        ADMUX = ((1 << REFS0) | (TEMP_0_PIN & 0x07));
        ADCSRA |= 1<<ADSC; // Start conversion
      #endif
      lcd_buttons_update();
      temp_state = 1;
      break;
    case 1: // Measure TEMP_0
      #if defined(TEMP_0_PIN) && (TEMP_0_PIN > -1)
        raw_temp_0_value += ADC;
      #endif
      temp_state = 2;
      break;
    case 2: // Prepare TEMP_BED
      #if defined(TEMP_BED_PIN) && (TEMP_BED_PIN > -1)
        #if TEMP_BED_PIN > 7
          ADCSRB = 1<<MUX5;
        #else
          ADCSRB = 0;
        #endif
        ADMUX = ((1 << REFS0) | (TEMP_BED_PIN & 0x07));
        ADCSRA |= 1<<ADSC; // Start conversion
      #endif
      lcd_buttons_update();
      temp_state = 3;
      break;
    case 3: // Measure TEMP_BED
      #if defined(TEMP_BED_PIN) && (TEMP_BED_PIN > -1)
        raw_temp_bed_value += ADC;
      #endif
      temp_state = 4;
      break;
    case 4: // Prepare TEMP_1
      #if defined(TEMP_1_PIN) && (TEMP_1_PIN > -1)
        #if TEMP_1_PIN > 7
          ADCSRB = 1<<MUX5;
        #else
          ADCSRB = 0;
        #endif
        ADMUX = ((1 << REFS0) | (TEMP_1_PIN & 0x07));
        ADCSRA |= 1<<ADSC; // Start conversion
      #endif
      lcd_buttons_update();
      temp_state = 5;
      break;
    case 5: // Measure TEMP_1
      #if defined(TEMP_1_PIN) && (TEMP_1_PIN > -1)
        raw_temp_1_value += ADC;
      #endif
      temp_state = 6;
      break;
    case 6: // Prepare TEMP_2
      #if defined(TEMP_2_PIN) && (TEMP_2_PIN > -1)
        #if TEMP_2_PIN > 7
          ADCSRB = 1<<MUX5;
        #else
          ADCSRB = 0;
        #endif
        ADMUX = ((1 << REFS0) | (TEMP_2_PIN & 0x07));
        ADCSRA |= 1<<ADSC; // Start conversion
      #endif
      lcd_buttons_update();
      temp_state = 7;
      break;
    case 7: // Measure TEMP_2
      #if defined(TEMP_2_PIN) && (TEMP_2_PIN > -1)
        raw_temp_2_value += ADC;
      #endif
      temp_state = 8;//change so that Filament Width is also measured
      
      break;
    case 8: //Prepare FILWIDTH 
     #if defined(FILWIDTH_PIN) && (FILWIDTH_PIN> -1) 
      #if FILWIDTH_PIN>7 
         ADCSRB = 1<<MUX5;
      #else
         ADCSRB = 0; 
      #endif 
      ADMUX = ((1 << REFS0) | (FILWIDTH_PIN & 0x07)); 
      ADCSRA |= 1<<ADSC; // Start conversion 
     #endif 
     lcd_buttons_update();       
     temp_state = 9; 
     break; 
    case 9:   //Measure FILWIDTH 
     #if defined(FILWIDTH_PIN) &&(FILWIDTH_PIN > -1) 
     //raw_filwidth_value += ADC;  //remove to use an IIR filter approach 
      if(ADC>102)  //check that ADC is reading a voltage > 0.5 volts, otherwise don't take in the data.
        {
    	raw_filwidth_value= raw_filwidth_value-(raw_filwidth_value>>7);  //multipliy raw_filwidth_value by 127/128
        
        raw_filwidth_value= raw_filwidth_value + ((unsigned long)ADC<<7);  //add new ADC reading 
        }
     #endif 
     temp_state = 0;   
      
     temp_count++;
     break;      
      
      
    case 10: //Startup, delay initial temp reading a tiny bit so the hardware can settle.
      temp_state = 0;
      break;
//    default:
//      SERIAL_ERROR_START;
//      SERIAL_ERRORLNPGM("Temp measurement error!");
//      break;
  }
    
  if(temp_count >= OVERSAMPLENR) // 10 * 16 * 1/(16000000/64/256)  = 164ms.
  {
    if (!temp_meas_ready) //Only update the raw values if they have been read. Else we could be updating them during reading.
    {
#ifndef HEATER_0_USES_MAX6675
      current_temperature_raw[0] = raw_temp_0_value;
#endif
#if EXTRUDERS > 1
      current_temperature_raw[1] = raw_temp_1_value;
#endif
#ifdef TEMP_SENSOR_1_AS_REDUNDANT
      redundant_temperature_raw = raw_temp_1_value;
#endif
#if EXTRUDERS > 2
      current_temperature_raw[2] = raw_temp_2_value;
#endif
      current_temperature_bed_raw = raw_temp_bed_value;
    }

//Add similar code for Filament Sensor - can be read any time since IIR filtering is used 
#if defined(FILWIDTH_PIN) &&(FILWIDTH_PIN > -1)
  current_raw_filwidth = raw_filwidth_value>>10;  //need to divide to get to 0-16384 range since we used 1/128 IIR filter approach 
#endif
    
    
    temp_meas_ready = true;
    temp_count = 0;
    raw_temp_0_value = 0;
    raw_temp_1_value = 0;
    raw_temp_2_value = 0;
    raw_temp_bed_value = 0;

#if HEATER_0_RAW_LO_TEMP > HEATER_0_RAW_HI_TEMP
    if(current_temperature_raw[0] <= maxttemp_raw[0]) {
#else
    if(current_temperature_raw[0] >= maxttemp_raw[0]) {
#endif
#ifndef HEATER_0_USES_MAX6675
        max_temp_error(0);
#endif
    }
#if HEATER_0_RAW_LO_TEMP > HEATER_0_RAW_HI_TEMP
    if(current_temperature_raw[0] >= minttemp_raw[0]) {
#else
    if(current_temperature_raw[0] <= minttemp_raw[0]) {
#endif
#ifndef HEATER_0_USES_MAX6675
        min_temp_error(0);
#endif
    }
#if EXTRUDERS > 1
#if HEATER_1_RAW_LO_TEMP > HEATER_1_RAW_HI_TEMP
    if(current_temperature_raw[1] <= maxttemp_raw[1]) {
#else
    if(current_temperature_raw[1] >= maxttemp_raw[1]) {
#endif
        max_temp_error(1);
    }
#if HEATER_1_RAW_LO_TEMP > HEATER_1_RAW_HI_TEMP
    if(current_temperature_raw[1] >= minttemp_raw[1]) {
#else
    if(current_temperature_raw[1] <= minttemp_raw[1]) {
#endif
        min_temp_error(1);
    }
#endif
#if EXTRUDERS > 2
#if HEATER_2_RAW_LO_TEMP > HEATER_2_RAW_HI_TEMP
    if(current_temperature_raw[2] <= maxttemp_raw[2]) {
#else
    if(current_temperature_raw[2] >= maxttemp_raw[2]) {
#endif
        max_temp_error(2);
    }
#if HEATER_2_RAW_LO_TEMP > HEATER_2_RAW_HI_TEMP
    if(current_temperature_raw[2] >= minttemp_raw[2]) {
#else
    if(current_temperature_raw[2] <= minttemp_raw[2]) {
#endif
        min_temp_error(2);
    }
#endif
  
  /* No bed MINTEMP error? */
#if defined(BED_MAXTEMP) && (TEMP_SENSOR_BED != 0)
# if HEATER_BED_RAW_LO_TEMP > HEATER_BED_RAW_HI_TEMP
    if(current_temperature_bed_raw <= bed_maxttemp_raw) {
#else
    if(current_temperature_bed_raw >= bed_maxttemp_raw) {
#endif
       target_temperature_bed = 0;
       bed_max_temp_error();
    }
#endif
  }
  
#ifdef BABYSTEPPING
  for(uint8_t axis=0;axis<3;axis++)
  {
    int curTodo=babystepsTodo[axis]; //get rid of volatile for performance
   
    if(curTodo>0)
    {
      babystep(axis,/*fwd*/true);
      babystepsTodo[axis]--; //less to do next time
    }
    else
    if(curTodo<0)
    {
      babystep(axis,/*fwd*/false);
      babystepsTodo[axis]++; //less to do next time
    }
  }
#endif //BABYSTEPPING
}

#ifdef PIDTEMP
// Apply the scale factors to the PID values


float scalePID_i(float i)
{
	return i*PID_dT;
}

float unscalePID_i(float i)
{
	return i/PID_dT;
}

float scalePID_d(float d)
{
    return d/PID_dT;
}

float unscalePID_d(float d)
{
	return d*PID_dT;
}

#endif //PIDTEMP