Clarify thermal_runaway_protection

- Add comments documenting `thermal_runaway_protection`
- Add an enum for the thermal runaway states
- Add macros for temperature helper functions
- Fix a glitch with the z probe sled in homeaxis

Marlin/Marlin_main.cpp

     sync_plan_position();
 
     // Engage Servo endstop if enabled
-    #ifdef SERVO_ENDSTOPS && !defined(Z_PROBE_SLED)
+    #if defined(SERVO_ENDSTOPS) && !defined(Z_PROBE_SLED)
 
       #if SERVO_LEVELING
         if (axis == Z_AXIS) engage_z_probe(); else
       }
     }
 
-    #if defined(FAN_PIN) && FAN_PIN > -1
+    #if HAS_FAN
       if (pin_number == FAN_PIN) fanSpeed = pin_status;
     #endif
 
 inline void gcode_M105() {
   if (setTargetedHotend(105)) return;
 
-  #if defined(TEMP_0_PIN) && TEMP_0_PIN > -1
+  #if HAS_TEMP_0
     SERIAL_PROTOCOLPGM("ok T:");
     SERIAL_PROTOCOL_F(degHotend(tmp_extruder),1);
     SERIAL_PROTOCOLPGM(" /");
     SERIAL_PROTOCOL_F(degTargetHotend(tmp_extruder),1);
-    #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
+    #if HAS_TEMP_BED
       SERIAL_PROTOCOLPGM(" B:");
       SERIAL_PROTOCOL_F(degBed(),1);
       SERIAL_PROTOCOLPGM(" /");
       SERIAL_PROTOCOL_F(degTargetBed(),1);
-    #endif //TEMP_BED_PIN
+    #endif
     for (int8_t cur_extruder = 0; cur_extruder < EXTRUDERS; ++cur_extruder) {
       SERIAL_PROTOCOLPGM(" T");
       SERIAL_PROTOCOL(cur_extruder);
   #endif
 
   #ifdef SHOW_TEMP_ADC_VALUES
-    #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
+    #if HAS_TEMP_BED
       SERIAL_PROTOCOLPGM("    ADC B:");
       SERIAL_PROTOCOL_F(degBed(),1);
       SERIAL_PROTOCOLPGM("C->");
     }
   #endif
 
-  SERIAL_PROTOCOLLN("");
+  SERIAL_EOL;
 }
 
-#if defined(FAN_PIN) && FAN_PIN > -1
+#if HAS_FAN
 
   /**
    * M106: Set Fan Speed
    */
   inline void gcode_M107() { fanSpeed = 0; }
 
-#endif //FAN_PIN
+#endif // HAS_FAN
 
 /**
  * M109: Wait for extruder(s) to reach temperature
             SERIAL_PROTOCOLLN( timetemp );
           }
           else {
-            SERIAL_PROTOCOLLN( "?" );
+            SERIAL_PROTOCOLLNPGM("?");
           }
         #else
-          SERIAL_PROTOCOLLN("");
+          SERIAL_EOL;
         #endif
         timetemp = millis();
       }
   starttime = previous_millis_cmd = millis();
 }
 
-#if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
+#if HAS_TEMP_BED
 
   /**
    * M190: Sxxx Wait for bed current temp to reach target temp. Waits only when heating
         SERIAL_PROTOCOL((int)active_extruder);
         SERIAL_PROTOCOLPGM(" B:");
         SERIAL_PROTOCOL_F(degBed(), 1);
-        SERIAL_PROTOCOLLN("");
+        SERIAL_EOL;
       }
       manage_heater();
       manage_inactivity();
   SERIAL_PROTOCOLPGM(" Z:");
   SERIAL_PROTOCOL(float(st_get_position(Z_AXIS))/axis_steps_per_unit[Z_AXIS]);
 
-  SERIAL_PROTOCOLLN("");
+  SERIAL_EOL;
 
   #ifdef SCARA
     SERIAL_PROTOCOLPGM("SCARA Theta:");
     SERIAL_PROTOCOL(delta[X_AXIS]);
     SERIAL_PROTOCOLPGM("   Psi+Theta:");
     SERIAL_PROTOCOL(delta[Y_AXIS]);
-    SERIAL_PROTOCOLLN("");
+    SERIAL_EOL;
     
     SERIAL_PROTOCOLPGM("SCARA Cal - Theta:");
     SERIAL_PROTOCOL(delta[X_AXIS]+home_offset[X_AXIS]);
     SERIAL_PROTOCOLPGM("   Psi+Theta (90):");
     SERIAL_PROTOCOL(delta[Y_AXIS]-delta[X_AXIS]-90+home_offset[Y_AXIS]);
-    SERIAL_PROTOCOLLN("");
+    SERIAL_EOL;
     
     SERIAL_PROTOCOLPGM("SCARA step Cal - Theta:");
     SERIAL_PROTOCOL(delta[X_AXIS]/90*axis_steps_per_unit[X_AXIS]);
     SERIAL_PROTOCOLPGM("   Psi+Theta:");
     SERIAL_PROTOCOL((delta[Y_AXIS]-delta[X_AXIS])/90*axis_steps_per_unit[Y_AXIS]);
-    SERIAL_PROTOCOLLN("");
-    SERIAL_PROTOCOLLN("");
+    SERIAL_EOL; SERIAL_EOL;
   #endif
 }
 
       SERIAL_PROTOCOL(servo_index);
       SERIAL_PROTOCOL(": ");
       SERIAL_PROTOCOL(servos[servo_index].read());
-      SERIAL_PROTOCOLLN("");
+      SERIAL_EOL;
     }
   }
 
         //Kc does not have scaling applied above, or in resetting defaults
         SERIAL_PROTOCOL(PID_PARAM(Kc, e));
       #endif
-      SERIAL_PROTOCOLLN("");    
+      SERIAL_EOL;    
     }
     else {
       SERIAL_ECHO_START;
     SERIAL_PROTOCOL(unscalePID_i(bedKi));
     SERIAL_PROTOCOL(" d:");
     SERIAL_PROTOCOL(unscalePID_d(bedKd));
-    SERIAL_PROTOCOLLN("");
+    SERIAL_EOL;
   }
 
 #endif // PIDTEMPBED
     if (code_seen('C')) lcd_setcontrast(code_value_long() & 0x3F);
     SERIAL_PROTOCOLPGM("lcd contrast value: ");
     SERIAL_PROTOCOL(lcd_contrast);
-    SERIAL_PROTOCOLLN("");
+    SERIAL_EOL;
   }
 
 #endif // DOGLCD
         zprobe_zoffset = -value; // compare w/ line 278 of ConfigurationStore.cpp
         SERIAL_ECHO_START;
         SERIAL_ECHOLNPGM(MSG_ZPROBE_ZOFFSET " " MSG_OK);
-        SERIAL_PROTOCOLLN("");
+        SERIAL_EOL;
       }
       else {
         SERIAL_ECHO_START;
         SERIAL_ECHO(Z_PROBE_OFFSET_RANGE_MIN);
         SERIAL_ECHOPGM(MSG_Z_MAX);
         SERIAL_ECHO(Z_PROBE_OFFSET_RANGE_MAX);
-        SERIAL_PROTOCOLLN("");
+        SERIAL_EOL;
       }
     }
     else {
       SERIAL_ECHO_START;
       SERIAL_ECHOLNPGM(MSG_ZPROBE_ZOFFSET " : ");
       SERIAL_ECHO(-zprobe_zoffset);
-      SERIAL_PROTOCOLLN("");
+      SERIAL_EOL;
     }
   }
 
         gcode_M109();
         break;
 
-      #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
+      #if HAS_TEMP_BED
         case 190: // M190 - Wait for bed heater to reach target.
           gcode_M190();
           break;
-      #endif //TEMP_BED_PIN
+      #endif // HAS_TEMP_BED
 
-      #if defined(FAN_PIN) && FAN_PIN > -1
+      #if HAS_FAN
         case 106: //M106 Fan On
           gcode_M106();
           break;
         case 107: //M107 Fan Off
           gcode_M107();
           break;
-      #endif //FAN_PIN
+      #endif // HAS_FAN
 
       #ifdef BARICUDA
         // PWM for HEATER_1_PIN
        max_temp = max(max_temp, degHotend(cur_extruder));
        max_temp = max(max_temp, degTargetHotend(cur_extruder));
     }
-    #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
+    #if HAS_TEMP_BED
       max_temp = max(max_temp, degTargetBed());
       max_temp = max(max_temp, degBed());
     #endif

Marlin/planner.cpp

     disable_e3();
   }
 
-  #if defined(FAN_PIN) && FAN_PIN > -1 // HAS_FAN
+  #if HAS_FAN
     #ifdef FAN_KICKSTART_TIME
       static unsigned long fan_kick_end;
       if (tail_fan_speed) {
     #else
       analogWrite(FAN_PIN, tail_fan_speed);
     #endif //!FAN_SOFT_PWM
-  #endif //FAN_PIN > -1
+  #endif // HAS_FAN
 
   #ifdef AUTOTEMP
     getHighESpeed();

Marlin/temperature.cpp

 /*
-  temperature.c - temperature control
+  temperature.cpp - temperature control
   Part of Marlin
   
  Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
  
  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"
 #define HAS_HEATER_THERMAL_PROTECTION (defined(THERMAL_RUNAWAY_PROTECTION_PERIOD) && THERMAL_RUNAWAY_PROTECTION_PERIOD > 0)
 #define HAS_BED_THERMAL_PROTECTION (defined(THERMAL_RUNAWAY_PROTECTION_BED_PERIOD) && THERMAL_RUNAWAY_PROTECTION_BED_PERIOD > 0 && TEMP_SENSOR_BED != 0)
 #if HAS_HEATER_THERMAL_PROTECTION || HAS_BED_THERMAL_PROTECTION
+  enum TRState { TRInactive, TRFirstHeating, TRStable };
   static bool thermal_runaway = false;
-  void thermal_runaway_protection(int *state, unsigned long *timer, float temperature, float target_temperature, int heater_id, int period_seconds, int hysteresis_degc);
+  void thermal_runaway_protection(TRState *state, unsigned long *timer, float temperature, float target_temperature, int heater_id, int period_seconds, int hysteresis_degc);
   #if HAS_HEATER_THERMAL_PROTECTION
-    static int thermal_runaway_state_machine[4]; // = {0,0,0,0};
+    static TRState thermal_runaway_state_machine[4] = { TRInactive, TRInactive, TRInactive, TRInactive };
     static unsigned long thermal_runaway_timer[4]; // = {0,0,0,0};
   #endif
   #if HAS_BED_THERMAL_PROTECTION
-    static int thermal_runaway_bed_state_machine;
+    static TRState thermal_runaway_bed_state_machine = { TRInactive, TRInactive, TRInactive, TRInactive };
     static unsigned long thermal_runaway_bed_timer;
   #endif
 #endif
     soft_pwm[extruder] = bias = d = PID_MAX / 2;
 
   // PID Tuning loop
-  for(;;) {
+  for (;;) {
 
     unsigned long ms = millis();
 
   // Loop through all extruders
   for (int e = 0; e < EXTRUDERS; e++) {
 
-    #if defined (THERMAL_RUNAWAY_PROTECTION_PERIOD) && THERMAL_RUNAWAY_PROTECTION_PERIOD > 0
+    #if HAS_HEATER_THERMAL_PROTECTION
       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
 
         disable_heater();
         _temp_error(0, PSTR(MSG_EXTRUDER_SWITCHED_OFF), PSTR(MSG_ERR_REDUNDANT_TEMP));
       }
-    #endif //TEMP_SENSOR_1_AS_REDUNDANT
+    #endif // TEMP_SENSOR_1_AS_REDUNDANT
 
   } // Extruders Loop
 
 }
 
 #if HAS_HEATER_THERMAL_PROTECTION || HAS_BED_THERMAL_PROTECTION
-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
-    {
-      unsigned long ms = millis();
-      if (temperature >= (target_temperature - hysteresis_degc))
-      {
-        *timer = ms;
-      } 
-      else if ( (ms - *timer) > ((unsigned long) period_seconds) * 1000)
+
+  void thermal_runaway_protection(TRState *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 = TRInactive;
+      *timer = 0;
+      return;
+    }
+
+    switch (*state) {
+      // Inactive state waits for a target temperature, then 
+      case TRInactive:
+        if (target_temperature > 0) *state = TRFirstHeating;
+        break;
+      // When first heating, wait for the temperature to be reached then go to Stable state
+      case TRFirstHeating:
+        if (temperature >= target_temperature) *state = TRStable;
+        break;
+      // While the temperature is stable watch for a bad temperature
+      case TRStable:
       {
-        SERIAL_ERROR_START;
-        SERIAL_ERRORLNPGM(MSG_THERMAL_RUNAWAY_STOP);
-        SERIAL_ERRORLN((int)heater_id);
-        LCD_ALERTMESSAGEPGM(MSG_THERMAL_RUNAWAY); // translatable
-        thermal_runaway = true;
-        while(1)
-        {
-          disable_heater();
-          disable_x();
-          disable_y();
-          disable_z();
-          disable_e0();
-          disable_e1();
-          disable_e2();
-          disable_e3();
-          manage_heater();
-          lcd_update();
+        // Whenever the current temperature is over the target (-hysteresis) restart the timer
+        if (temperature >= target_temperature - hysteresis_degc) {
+          *timer = millis();
         }
-      }
-    } break;
+        // If the timer goes too long without a reset, trigger shutdown
+        else if (millis() > *timer + period_seconds * 1000UL) {
+          SERIAL_ERROR_START;
+          SERIAL_ERRORLNPGM(MSG_THERMAL_RUNAWAY_STOP);
+          SERIAL_ERRORLN((int)heater_id);
+          LCD_ALERTMESSAGEPGM(MSG_THERMAL_RUNAWAY);
+          thermal_runaway = true;
+          for (;;) {
+            disable_heater();
+            disable_x();
+            disable_y();
+            disable_z();
+            disable_e0();
+            disable_e1();
+            disable_e2();
+            disable_e3();
+            manage_heater();
+            lcd_update();
+          }
+        }
+      } break;
+    }
   }
-}
-#endif //THERMAL_RUNAWAY_PROTECTION_PERIOD
 
+#endif // HAS_HEATER_THERMAL_PROTECTION
 
 void disable_heater() {
   for (int i=0; i<EXTRUDERS; i++) setTargetHotend(0, i);

Marlin/temperature.h

   along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#ifndef temperature_h
-#define temperature_h 
+#ifndef TEMPERATURE_H
+#define TEMPERATURE_H 
 
 #include "Marlin.h"
 #include "planner.h"
 FORCE_INLINE bool isCoolingHotend(uint8_t extruder) { return target_temperature[extruder] < current_temperature[extruder]; }
 FORCE_INLINE bool isCoolingBed() { return target_temperature_bed < current_temperature_bed; }
 
-#define degHotend0() degHotend(0)
-#define degTargetHotend0() degTargetHotend(0)
-#define setTargetHotend0(_celsius) setTargetHotend((_celsius), 0)
-#define isHeatingHotend0() isHeatingHotend(0)
-#define isCoolingHotend0() isCoolingHotend(0)
+#define HOTEND_ROUTINES(NR) \
+  FORCE_INLINE float degHotend##NR() { return degHotend(NR); } \
+  FORCE_INLINE float degTargetHotend##NR() { return degTargetHotend(NR); } \
+  FORCE_INLINE void setTargetHotend##NR(const float c) { setTargetHotend(c, NR); } \
+  FORCE_INLINE bool isHeatingHotend##NR() { return isHeatingHotend(NR); } \
+  FORCE_INLINE bool isCoolingHotend##NR() { return isCoolingHotend(NR); }
+HOTEND_ROUTINES(0);
 #if EXTRUDERS > 1
-  #define degHotend1() degHotend(1)
-  #define degTargetHotend1() degTargetHotend(1)
-  #define setTargetHotend1(_celsius) setTargetHotend((_celsius), 1)
-  #define isHeatingHotend1() isHeatingHotend(1)
-  #define isCoolingHotend1() isCoolingHotend(1)
+  HOTEND_ROUTINES(1);
 #else
-  #define setTargetHotend1(_celsius) do{}while(0)
+  #define setTargetHotend1(c) do{}while(0)
 #endif
 #if EXTRUDERS > 2
-  #define degHotend2() degHotend(2)
-  #define degTargetHotend2() degTargetHotend(2)
-  #define setTargetHotend2(_celsius) setTargetHotend((_celsius), 2)
-  #define isHeatingHotend2() isHeatingHotend(2)
-  #define isCoolingHotend2() isCoolingHotend(2)
+  HOTEND_ROUTINES(2);
 #else
-  #define setTargetHotend2(_celsius) do{}while(0)
+  #define setTargetHotend2(c) do{}while(0)
 #endif
 #if EXTRUDERS > 3
-  #define degHotend3() degHotend(3)
-  #define degTargetHotend3() degTargetHotend(3)
-  #define setTargetHotend3(_celsius) setTargetHotend((_celsius), 3)
-  #define isHeatingHotend3() isHeatingHotend(3)
-  #define isCoolingHotend3() isCoolingHotend(3)
+  HOTEND_ROUTINES(3);
 #else
-  #define setTargetHotend3(_celsius) do{}while(0)
-#endif
-#if EXTRUDERS > 4
-  #error Invalid number of extruders
+  #define setTargetHotend3(c) do{}while(0)
 #endif
 
 int getHeaterPower(int heater);
   #endif
 }
 
-
-#endif
+#endif // TEMPERATURE_H