add config parameters for controlling temperature

config.py

@@ -57,7 +57,7 @@ sensor_time_wait = 2
 # These parameters work well with the simulated oven. You must tune them
 # to work well with your specific kiln. Note that the integral pid_ki is
 # inverted so that a smaller number means more integral action.
-pid_kp = 25   # Proportional 
+pid_kp = 25   # Proportional
 pid_ki = 200  # Integral
 pid_kd = 200  # Derivative
 
@@ -66,11 +66,11 @@ pid_kd = 200  # Derivative
 #
 # Initial heating and Integral Windup
 #
-# During initial heating, if the temperature is constantly under the 
+# During initial heating, if the temperature is constantly under the
 # setpoint,large amounts of Integral can accumulate. This accumulation
 # causes the kiln to run above the setpoint for potentially a long
 # period of time. These settings allow integral accumulation only when
-# the temperature is within stop_integral_windup_margin percent below 
+# the temperature is within stop_integral_windup_margin percent below
 # or above the setpoint. This applies only to the integral.
 stop_integral_windup = True
 stop_integral_windup_margin = 10
@@ -96,20 +96,20 @@ sim_R_ho_air   = 0.05   # K/W  " with internal air circulation
 # If you change the temp_scale, all settings in this file are assumed to
 # be in that scale.
 
-temp_scale          = "f" # c = Celsius | f = Fahrenheit - Unit to display 
+temp_scale          = "f" # c = Celsius | f = Fahrenheit - Unit to display
 time_scale_slope    = "h" # s = Seconds | m = Minutes | h = Hours - Slope displayed in temp_scale per time_scale_slope
 time_scale_profile  = "m" # s = Seconds | m = Minutes | h = Hours - Enter and view target time in time_scale_profile
 
 # emergency shutoff the profile if this temp is reached or exceeded.
 # This just shuts off the profile. If your SSR is working, your kiln will
-# naturally cool off. If your SSR has failed/shorted/closed circuit, this 
+# naturally cool off. If your SSR has failed/shorted/closed circuit, this
 # means your kiln receives full power until your house burns down.
 # this should not replace you watching your kiln or use of a kiln-sitter
-emergency_shutoff_temp = 2264 #cone 7 
+emergency_shutoff_temp = 2264 #cone 7
 
-# If the kiln cannot heat or cool fast enough and is off by more than 
+# If the kiln cannot heat or cool fast enough and is off by more than
 # kiln_must_catch_up_max_error  the entire schedule is shifted until
-# the desired temperature is reached. If your kiln cannot attain the 
+# the desired temperature is reached. If your kiln cannot attain the
 # wanted temperature, the schedule will run forever.
 kiln_must_catch_up = True
 kiln_must_catch_up_max_error = 10 #degrees
@@ -119,3 +119,13 @@ kiln_must_catch_up_max_error = 10 #degrees
 # set set this offset to -4 to compensate.  This probably means you have a
 # cheap thermocouple.  Invest in a better thermocouple.
 thermocouple_offset=0
+
+# some kilns/thermocouples start erroneously reporting "short" errors at higher temperatures
+# due to plasma forming in the kiln.
+# Set this to False to ignore these errors and assume the temperature reading was correct anyway
+honour_theromocouple_short_errors = True
+
+# number of samples of temperature to average.
+# If you suffer from ghe high temperature kiln issue and have set honour_theromocouple_short_errors to False,
+# you will likely need to increase this (eg I use 40)
+temperature_average_samples = 5

lib/max31855.py

@@ -26,7 +26,7 @@ class MAX31855(object):
         self.units = units
         self.data = None
         self.board = board
-        self.noConnection = self.shortToGround = self.shortToVCC = False
+        self.noConnection = self.shortToGround = self.shortToVCC = self.unknownError = False
 
         # Initialize needed GPIO
         GPIO.setmode(self.board)
@@ -74,9 +74,10 @@ class MAX31855(object):
         if anyErrors:
             self.noConnection = (data_32 & 0x00000001) != 0       # OC bit, D0
             self.shortToGround = (data_32 & 0x00000002) != 0      # SCG bit, D1
-            self.shortToVCC = (data_32 & 0x00000004) != 0
+            self.shortToVCC = (data_32 & 0x00000004) != 0         # SCV bit, D2
+            self.unknownError = not (self.noConnection | self.shortToGround | self.shortToVCC)    # Errk!
         else:
-            self.noConnection = self.shortToGround = self.shortToVCC = False
+            self.noConnection = self.shortToGround = self.shortToVCC = self.unknownError = False
 
     def data_to_tc_temperature(self, data_32 = None):
         '''Takes an integer and returns a thermocouple temperature in celsius.'''

lib/oven.py

@@ -8,7 +8,6 @@ import config
 
 log = logging.getLogger(__name__)
 
-TEMPERATURE_MOVING_AVERAGE_SAMPLES = 40
 
 class Output(object):
     def __init__(self):
@@ -124,15 +123,24 @@ class TempSensorReal(TempSensor):
         temps = []
         while True:
             temp = self.thermocouple.get()
-            temps.append(temp)
-            if len(temps) > TEMPERATURE_MOVING_AVERAGE_SAMPLES:
-                del temps[0]
-
-            if len(temps):
-                self.temperature = sum(temps) / len(temps)
             self.noConnection = self.thermocouple.noConnection
             self.shortToGround = self.thermocouple.shortToGround
             self.shortToVCC = self.thermocouple.shortToVCC
+            self.unknownError = self.thermocouple.unknownError
+
+            is_bad_value = self.noConnection | self.unknownError
+            if config.honour_theromocouple_short_errors:
+                is_bad_value |= self.shortToGround | self.shortToVCC
+
+            if not is_bad_value:
+                temps.append(temp)
+                if len(temps) > config.temperature_average_samples:
+                    del temps[0]
+            else:
+                log.error(f"Problem reading temp N/C:{self.noConnection} GND:{self.shortToGround} VCC:{self.shortToVCC} ???:{self.unknownError}")
+
+            if len(temps):
+                self.temperature = sum(temps) / len(temps)
             time.sleep(self.sleeptime)
 
 class Oven(threading.Thread):
@@ -167,6 +175,9 @@ class Oven(threading.Thread):
         if self.board.temp_sensor.shortToVCC:
             log.info("Refusing to start profile - thermocouple short to VCC")
             return
+        if self.board.temp_sensor.unknownError:
+            log.info("Refusing to start profile - thermocouple unknown error")
+            return
 
         log.info("Running schedule %s" % profile.name)
         self.profile = profile
@@ -217,6 +228,10 @@ class Oven(threading.Thread):
             log.info("emergency!!! lost connection to thermocouple, shutting down")
             self.reset()
 
+        if self.board.temp_sensor.unknownError:
+            log.info("emergency!!! unknown thermocouple error, shutting down")
+            self.reset()
+
     def reset_if_schedule_ended(self):
         if self.runtime > self.totaltime:
             log.info("schedule ended, shutting down")