Implement MIN/MAX AMBIENT safety checks

Take advantage of the NTC thermistor found on the Einsy as an additional
safety measure, following the steps of the other MIN/MAXTEMP errors.

Introduce two configurable params AMBIENT_MINTEMP and AMBIENT_MAXTEMP
in the variant defines and set them for the MK3/MK3S to -30/+100
respectively.

AMBIENT_MINTEMP is primarily intended to catch a defective board
thermistor (to ensure MAXTEMP would be properly triggered) and thus the
trigger temperature is set just above the sensing limit and well below
the operating range.

AMBIENT_MAXTEMP is set at 100C, which is instead 20C above the maximum
recommended operating temperature of the Einsy. The NTC thermistor is
located just above the main power connector on the bottom of the board,
and could also help in detecting a faulty connection which can result in
rapid overheating of the contacts.

As for MAXTEMP, we cut power to the heaters, print fan and motors to
reduce power draw. Resume is not possible except by resetting the
printer, since the user is highly advised to inspect the board for
problems before attempting to continue.

Firmware/Configuration_adv.h

@@ -436,6 +436,10 @@ const unsigned int dropsegments=5; //everything with less than this number of st
   #undef BED_MINTEMP
   #undef BED_MAXTEMP
 #endif
+#if TEMP_SENSOR_AMBIENT == 0
+  #undef AMBIENT_MINTEMP
+  #undef AMBIENT_MAXTEMP
+#endif
 
 
 #endif //__CONFIGURATION_ADV_H

Firmware/temperature.cpp

@@ -180,6 +180,12 @@ static int bed_minttemp_raw = HEATER_BED_RAW_LO_TEMP;
 #ifdef BED_MAXTEMP
 static int bed_maxttemp_raw = HEATER_BED_RAW_HI_TEMP;
 #endif
+#ifdef AMBIENT_MINTEMP
+static int ambient_minttemp_raw = AMBIENT_RAW_LO_TEMP;
+#endif
+#ifdef AMBIENT_MAXTEMP
+static int ambient_maxttemp_raw = AMBIENT_RAW_HI_TEMP;
+#endif
 
 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 );
@@ -1183,6 +1189,25 @@ void tp_init()
 #endif
   }
 #endif //BED_MAXTEMP
+
+#ifdef AMBIENT_MINTEMP
+  while(analog2tempAmbient(ambient_minttemp_raw) < AMBIENT_MINTEMP) {
+#if HEATER_AMBIENT_RAW_LO_TEMP < HEATER_AMBIENT_RAW_HI_TEMP
+    ambient_minttemp_raw += OVERSAMPLENR;
+#else
+    ambient_minttemp_raw -= OVERSAMPLENR;
+#endif
+  }
+#endif //AMBIENT_MINTEMP
+#ifdef AMBIENT_MAXTEMP
+  while(analog2tempAmbient(ambient_maxttemp_raw) > AMBIENT_MAXTEMP) {
+#if HEATER_AMBIENT_RAW_LO_TEMP < HEATER_AMBIENT_RAW_HI_TEMP
+    ambient_maxttemp_raw -= OVERSAMPLENR;
+#else
+    ambient_maxttemp_raw += OVERSAMPLENR;
+#endif
+  }
+#endif //AMBIENT_MAXTEMP
 }
 
 #if (defined (TEMP_RUNAWAY_BED_HYSTERESIS) && TEMP_RUNAWAY_BED_TIMEOUT > 0) || (defined (TEMP_RUNAWAY_EXTRUDER_HYSTERESIS) && TEMP_RUNAWAY_EXTRUDER_TIMEOUT > 0)
@@ -1509,6 +1534,35 @@ void bed_min_temp_error(void) {
 #endif
 }
 
+
+#ifdef AMBIENT_THERMISTOR
+void ambient_max_temp_error(void) {
+    if(IsStopped() == false) {
+        SERIAL_ERROR_START;
+        SERIAL_ERRORLNPGM("Heaters switched off. MAXTEMP AMBIENT triggered !");
+        LCD_ALERTMESSAGEPGM("Err: MAXTEMP AMBIENT");
+    }
+#ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
+    Stop();
+#endif
+}
+
+void ambient_min_temp_error(void) {
+#ifdef DEBUG_DISABLE_MINTEMP
+	return;
+#endif
+    if(IsStopped() == false) {
+        SERIAL_ERROR_START;
+        SERIAL_ERRORLNPGM("Heaters switched off. MINTEMP AMBIENT triggered !");
+        LCD_ALERTMESSAGEPGM("Err: MINTEMP AMBIENT");
+    }
+#ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
+    Stop();
+#endif
+}
+#endif
+
+
 #ifdef HEATER_0_USES_MAX6675
 #define MAX6675_HEAT_INTERVAL 250
 long max6675_previous_millis = MAX6675_HEAT_INTERVAL;
@@ -1994,7 +2048,16 @@ void check_max_temp()
        bed_max_temp_error();
     }
 #endif
-
+//ambient
+#if defined(AMBIENT_MAXTEMP) && (TEMP_SENSOR_AMBIENT != 0)
+#if AMBIENT_RAW_LO_TEMP > AMBIENT_RAW_HI_TEMP
+    if (current_temperature_raw_ambient <= ambient_maxttemp_raw) {
+#else
+    if (current_temperature_raw_ambient >= ambient_maxttemp_raw) {
+#endif
+       ambient_max_temp_error();
+    }
+#endif
 }
 //! number of repeating the same state with consecutive step() calls
 //! used to slow down text switching
@@ -2089,12 +2152,32 @@ void check_min_temp_bed()
 	}
 }
 
+#ifdef AMBIENT_MINTEMP
+void check_min_temp_ambient()
+{
+#if AMBIENT_RAW_LO_TEMP > AMBIENT_RAW_HI_TEMP
+	if (current_temperature_raw_ambient >= ambient_minttemp_raw) {
+#else
+	if (current_temperature_raw_ambient <= ambient_minttemp_raw) {
+#endif
+		ambient_min_temp_error();
+	}
+}
+#endif
+
 void check_min_temp()
 {
 static bool bCheckingOnHeater=false;              // state variable, which allows to short no-checking delay (is set, when temperature is (first time) over heaterMintemp)
 static bool bCheckingOnBed=false;                 // state variable, which allows to short no-checking delay (is set, when temperature is (first time) over bedMintemp)
 #ifdef AMBIENT_THERMISTOR
-if(current_temperature_raw_ambient>(OVERSAMPLENR*MINTEMP_MINAMBIENT_RAW)) // thermistor is NTC type, so operator is ">" ;-)
+#ifdef AMBIENT_MINTEMP
+check_min_temp_ambient();
+#endif
+#if AMBIENT_RAW_LO_TEMP > AMBIENT_RAW_HI_TEMP
+if(current_temperature_raw_ambient>(OVERSAMPLENR*MINTEMP_MINAMBIENT_RAW)) // thermistor is NTC type
+#else
+if(current_temperature_raw_ambient=<(OVERSAMPLENR*MINTEMP_MINAMBIENT_RAW))
+#endif
      {                                            // ambient temperature is low
 #endif //AMBIENT_THERMISTOR
 // *** 'common' part of code for MK2.5 & MK3

Firmware/thermistortables.h

@@ -1213,6 +1213,8 @@ const short temptable_1047[][2] PROGMEM = {
 #endif
 
 #if (THERMISTORAMBIENT == 2000) //100k thermistor NTCG104LH104JT1
+# define AMBIENT_RAW_HI_TEMP 0
+# define AMBIENT_RAW_LO_TEMP 16383
 const short temptable_2000[][2] PROGMEM = {
 // Source: https://product.tdk.com/info/en/catalog/datasheets/503021/tpd_ntc-thermistor_ntcg_en.pdf
 // Calculated using 4.7kohm pullup, voltage divider math, and manufacturer provided temp/resistance

Firmware/variants/1_75mm_MK3-EINSy10a-E3Dv6full.h

@@ -296,6 +296,7 @@
 #endif
 #define DETECT_SUPERPINDA
 #define PINDA_MINTEMP BED_MINTEMP
+#define AMBIENT_MINTEMP -30
 
 // Maxtemps
 #if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
@@ -306,6 +307,7 @@
 #define HEATER_1_MAXTEMP 305
 #define HEATER_2_MAXTEMP 305
 #define BED_MAXTEMP 125
+#define AMBIENT_MAXTEMP 100
 
 #if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
 // Define PID constants for extruder with PT100

Firmware/variants/1_75mm_MK3S-EINSy10a-E3Dv6full.h

@@ -298,6 +298,7 @@
 #endif
 #define DETECT_SUPERPINDA
 #define PINDA_MINTEMP BED_MINTEMP
+#define AMBIENT_MINTEMP -30
 
 // Maxtemps
 #if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
@@ -308,6 +309,7 @@
 #define HEATER_1_MAXTEMP 305
 #define HEATER_2_MAXTEMP 305
 #define BED_MAXTEMP 125
+#define AMBIENT_MAXTEMP 100
 
 #if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
 // Define PID constants for extruder with PT100