heater: Introduce smooth_time config option; remove pid_deriv_time

Add generic temperature smoothing to the Heater class.  This is useful
to avoid min_extrude_temp and verify_heater errors due to measurement
noise.

Rename the pid_deriv_time config option to smooth_time so that the
smoothing amount need only be specified once.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/example.cfg

@@ -161,6 +161,10 @@ sensor_pin: analog13
 #adc_voltage: 5.0
 #   The ADC comparison voltage. This parameter is only valid when the
 #   sensor is an AD595 or "PT100 INA826". The default is 5 volts.
+#smooth_time: 2.0
+#   A time value (in seconds) over which temperature measurements will
+#   be smoothed to reduce the impact of measurement noise. The default
+#   is 2 seconds.
 control: pid
 #   Control algorithm (either pid or watermark). This parameter must
 #   be provided.
@@ -173,10 +177,6 @@ pid_Ki: 1.08
 pid_Kd: 114
 #   Kd is the "derivative" constant for the pid. This parameter must
 #   be provided for PID heaters.
-#pid_deriv_time: 2.0
-#   A time value (in seconds) over which the derivative in the pid
-#   will be smoothed to reduce the impact of measurement noise. The
-#   default is 2 seconds.
 #pid_integral_max:
 #   The maximum "windup" the integral term may accumulate. The default
 #   is to use the same value as max_power.

klippy/extras/pid_calibrate.py

@@ -86,7 +86,7 @@ class ControlAutoTune:
             if temp > self.peak:
                 self.peak = temp
                 self.peak_time = read_time
-    def check_busy(self, eventtime, last_temp, target_temp):
+    def check_busy(self, eventtime, smoothed_temp, target_temp):
         if self.heating or len(self.peaks) < 12:
             return True
         return False

klippy/heater.py

@@ -21,23 +21,34 @@ class error(Exception):
 class Heater:
     error = error
     def __init__(self, config, sensor):
-        self.sensor = sensor
-        self.name = config.get_name()
         printer = config.get_printer()
+        self.name = config.get_name()
+        # Setup sensor
+        self.sensor = sensor
         self.min_temp = config.getfloat('min_temp', minval=KELVIN_TO_CELCIUS)
         self.max_temp = config.getfloat('max_temp', above=self.min_temp)
         self.sensor.setup_minmax(self.min_temp, self.max_temp)
         self.sensor.setup_callback(self.temperature_callback)
         self.pwm_delay = self.sensor.get_report_time_delta()
+        # Setup temperature checks
         self.min_extrude_temp = config.getfloat(
             'min_extrude_temp', 170., minval=self.min_temp, maxval=self.max_temp)
+        is_fileoutput = printer.get_start_args().get('debugoutput') is not None
+        self.can_extrude = self.min_extrude_temp <= 0. or is_fileoutput
         self.max_power = config.getfloat('max_power', 1., above=0., maxval=1.)
+        self.smooth_time = config.getfloat('smooth_time', 2., above=0.)
+        self.inv_smooth_time = 1. / self.smooth_time
         self.lock = threading.Lock()
-        self.last_temp = 0.
+        self.last_temp = self.smoothed_temp = self.target_temp = 0.
         self.last_temp_time = 0.
-        self.target_temp = 0.
+        # pwm caching
+        self.next_pwm_time = 0.
+        self.last_pwm_value = 0.
+        # Setup control algorithm sub-class
         algos = {'watermark': ControlBangBang, 'pid': ControlPID}
         algo = config.getchoice('control', algos)
+        self.control = algo(self, config)
+        # Setup output heater pin
         heater_pin = config.get('heater_pin')
         ppins = printer.lookup_object('pins')
         if algo is ControlBangBang and self.max_power == 1.:
@@ -48,12 +59,6 @@ class Heater:
                 'pwm_cycle_time', 0.100, above=0., maxval=self.pwm_delay)
             self.mcu_pwm.setup_cycle_time(pwm_cycle_time)
         self.mcu_pwm.setup_max_duration(MAX_HEAT_TIME)
-        is_fileoutput = self.mcu_pwm.get_mcu().is_fileoutput()
-        self.can_extrude = self.min_extrude_temp <= 0. or is_fileoutput
-        self.control = algo(self, config)
-        # pwm caching
-        self.next_pwm_time = 0.
-        self.last_pwm_value = 0.
         # Load additional modules
         printer.try_load_module(config, "verify_heater %s" % (self.name,))
         printer.try_load_module(config, "pid_calibrate")
@@ -73,16 +78,22 @@ class Heater:
         self.mcu_pwm.set_pwm(pwm_time, value)
     def temperature_callback(self, read_time, temp):
         with self.lock:
+            time_diff = read_time - self.last_temp_time
             self.last_temp = temp
             self.last_temp_time = read_time
-            self.can_extrude = (temp >= self.min_extrude_temp)
             self.control.temperature_update(read_time, temp, self.target_temp)
+            temp_diff = temp - self.smoothed_temp
+            adj_time = min(time_diff * self.inv_smooth_time, 1.)
+            self.smoothed_temp += temp_diff * adj_time
+            self.can_extrude = (self.smoothed_temp >= self.min_extrude_temp)
         #logging.debug("temp: %.3f %f = %f", read_time, temp)
     # External commands
     def get_pwm_delay(self):
         return self.pwm_delay
     def get_max_power(self):
         return self.max_power
+    def get_smooth_time(self):
+        return self.smooth_time
     def set_temp(self, print_time, degrees):
         if degrees and (degrees < self.min_temp or degrees > self.max_temp):
             raise error("Requested temperature (%.1f) out of range (%.1f:%.1f)"
@@ -94,11 +105,11 @@ class Heater:
         with self.lock:
             if self.last_temp_time < print_time:
                 return 0., self.target_temp
-            return self.last_temp, self.target_temp
+            return self.smoothed_temp, self.target_temp
     def check_busy(self, eventtime):
         with self.lock:
             return self.control.check_busy(
-                eventtime, self.last_temp, self.target_temp)
+                eventtime, self.smoothed_temp, self.target_temp)
     def set_control(self, control):
         with self.lock:
             old_control = self.control
@@ -120,8 +131,8 @@ class Heater:
     def get_status(self, eventtime):
         with self.lock:
             target_temp = self.target_temp
-            last_temp = self.last_temp
+            smoothed_temp = self.smoothed_temp
-        return {'temperature': last_temp, 'target': target_temp}
+        return {'temperature': smoothed_temp, 'target': target_temp}
 
 
 ######################################################################
@@ -143,8 +154,8 @@ class ControlBangBang:
             self.heater.set_pwm(read_time, self.heater_max_power)
         else:
             self.heater.set_pwm(read_time, 0.)
-    def check_busy(self, eventtime, last_temp, target_temp):
+    def check_busy(self, eventtime, smoothed_temp, target_temp):
-        return last_temp < target_temp-self.max_delta
+        return smoothed_temp < target_temp-self.max_delta
 
 
 ######################################################################
@@ -161,7 +172,7 @@ class ControlPID:
         self.Kp = config.getfloat('pid_Kp') / PID_PARAM_BASE
         self.Ki = config.getfloat('pid_Ki') / PID_PARAM_BASE
         self.Kd = config.getfloat('pid_Kd') / PID_PARAM_BASE
-        self.min_deriv_time = config.getfloat('pid_deriv_time', 2., above=0.)
+        self.min_deriv_time = heater.get_smooth_time()
         imax = config.getfloat('pid_integral_max', self.heater_max_power,
                                minval=0.)
         self.temp_integ_max = imax / self.Ki
@@ -194,8 +205,8 @@ class ControlPID:
         self.prev_temp_deriv = temp_deriv
         if co == bounded_co:
             self.prev_temp_integ = temp_integ
-    def check_busy(self, eventtime, last_temp, target_temp):
+    def check_busy(self, eventtime, smoothed_temp, target_temp):
-        temp_diff = target_temp - last_temp
+        temp_diff = target_temp - smoothed_temp
         return (abs(temp_diff) > PID_SETTLE_DELTA
                 or abs(self.prev_temp_deriv) > PID_SETTLE_SLOPE)