heaters: Make heater.py an "extras" module

The heater logic is an independent module that does not need to be
treated as part of the "core" klipper code.

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

14 files changed, 367 insertions, 35 deletions

diff --git a/klippy/extras/adc_temperature.py b/klippy/extras/adc_temperature.py
index 0ec13776..f00ba778 100644
--- a/klippy/extras/adc_temperature.py
+++ b/klippy/extras/adc_temperature.py
@@ -273,7 +273,7 @@ PT1000 = [
 
 def load_config(config):
     # Register default sensors
-    pheater = config.get_printer().lookup_object("heater")
+    pheaters = config.get_printer().try_load_module(config, "heaters")
     for sensor_type, params in [("AD595", AD595),
                                 ("AD8494", AD8494),
                                 ("AD8495", AD8495),
@@ -282,17 +282,17 @@ def load_config(config):
                                 ("PT100 INA826", PT100)]:
         func = (lambda config, params=params:
                 PrinterADCtoTemperature(config, LinearVoltage(config, params)))
-        pheater.add_sensor_factory(sensor_type, func)
+        pheaters.add_sensor_factory(sensor_type, func)
     for sensor_type, params in [("PT1000", PT1000)]:
         func = (lambda config, params=params:
                 PrinterADCtoTemperature(config,
                                         LinearResistance(config, params)))
-        pheater.add_sensor_factory(sensor_type, func)
+        pheaters.add_sensor_factory(sensor_type, func)
 
 def load_config_prefix(config):
     if config.get("resistance1", None) is None:
         custom_sensor = CustomLinearVoltage(config)
     else:
         custom_sensor = CustomLinearResistance(config)
-    pheater = config.get_printer().lookup_object("heater")
-    pheater.add_sensor_factory(custom_sensor.name, custom_sensor.create)
+    pheaters = config.get_printer().try_load_module(config, "heaters")
+    pheaters.add_sensor_factory(custom_sensor.name, custom_sensor.create)
diff --git a/klippy/extras/bme280.py b/klippy/extras/bme280.py
index 0809ac6d..f5fba66e 100644
--- a/klippy/extras/bme280.py
+++ b/klippy/extras/bme280.py
@@ -198,5 +198,5 @@ class BME280:
 
 def load_config(config):
     # Register sensor
-    pheater = config.get_printer().lookup_object("heater")
-    pheater.add_sensor_factory("BME280", BME280)
+    pheaters = config.get_printer().try_load_module(config, "heaters")
+    pheaters.add_sensor_factory("BME280", BME280)
diff --git a/klippy/extras/controller_fan.py b/klippy/extras/controller_fan.py
index adf78ccc..ccd617a2 100644
--- a/klippy/extras/controller_fan.py
+++ b/klippy/extras/controller_fan.py
@@ -14,6 +14,7 @@ class ControllerFan:
         self.stepper_names = []
         self.stepper_enable = self.printer.try_load_module(config,
                                                            'stepper_enable')
+        self.printer.try_load_module(config, 'heaters')
         self.heaters = []
         self.fan = fan.PrinterFan(config)
         self.mcu = self.fan.mcu_fan.get_mcu()
@@ -27,8 +28,8 @@ class ControllerFan:
         self.heater_name = config.get("heater", "extruder")
         self.last_on = self.idle_timeout
     def handle_ready(self):
-        pheater = self.printer.lookup_object('heater')
-        self.heaters = [pheater.lookup_heater(n.strip())
+        pheaters = self.printer.lookup_object('heaters')
+        self.heaters = [pheaters.lookup_heater(n.strip())
                         for n in self.heater_name.split(',')]
         kin = self.printer.lookup_object('toolhead').get_kinematics()
         self.stepper_names = [s.get_name() for s in kin.get_steppers()]
diff --git a/klippy/extras/heater_bed.py b/klippy/extras/heater_bed.py
index c3505528..c2f56a99 100644
--- a/klippy/extras/heater_bed.py
+++ b/klippy/extras/heater_bed.py
@@ -7,8 +7,8 @@
 class PrinterHeaterBed:
     def __init__(self, config):
         self.printer = config.get_printer()
-        pheater = self.printer.lookup_object('heater')
-        self.heater = pheater.setup_heater(config, 'B')
+        pheaters = self.printer.try_load_module(config, 'heaters')
+        self.heater = pheaters.setup_heater(config, 'B')
         self.get_status = self.heater.get_status
         self.stats = self.heater.stats
         # Register commands
@@ -21,8 +21,8 @@ class PrinterHeaterBed:
         temp = gcode.get_float('S', params, 0.)
         self.heater.set_temp(temp)
         if wait and temp:
-            pheater = self.printer.lookup_object('heater')
-            pheater.wait_for_temperature(self.heater)
+            pheaters = self.printer.lookup_object('heaters')
+            pheaters.wait_for_temperature(self.heater)
     def cmd_M190(self, params):
         # Set Bed Temperature and Wait
         self.cmd_M140(params, wait=True)
diff --git a/klippy/extras/heater_fan.py b/klippy/extras/heater_fan.py
index 337dcc09..4a3ace84 100644
--- a/klippy/extras/heater_fan.py
+++ b/klippy/extras/heater_fan.py
@@ -10,6 +10,7 @@ PIN_MIN_TIME = 0.100
 class PrinterHeaterFan:
     def __init__(self, config):
         self.printer = config.get_printer()
+        self.printer.try_load_module(config, 'heaters')
         self.printer.register_event_handler("klippy:ready", self.handle_ready)
         self.heater_name = config.get("heater", "extruder")
         self.heater_temp = config.getfloat("heater_temp", 50.0)
@@ -18,8 +19,8 @@ class PrinterHeaterFan:
         self.mcu = self.fan.mcu_fan.get_mcu()
         self.fan_speed = config.getfloat("fan_speed", 1., minval=0., maxval=1.)
     def handle_ready(self):
-        pheater = self.printer.lookup_object('heater')
-        self.heaters = [pheater.lookup_heater(n.strip())
+        pheaters = self.printer.lookup_object('heaters')
+        self.heaters = [pheaters.lookup_heater(n.strip())
                         for n in self.heater_name.split(',')]
         reactor = self.printer.get_reactor()
         reactor.register_timer(self.callback, reactor.NOW)
diff --git a/klippy/extras/heater_generic.py b/klippy/extras/heater_generic.py
index fbe13edc..564e4179 100644
--- a/klippy/extras/heater_generic.py
+++ b/klippy/extras/heater_generic.py
@@ -5,4 +5,5 @@
 # This file may be distributed under the terms of the GNU GPLv3 license.
 
 def load_config_prefix(config):
-    return config.get_printer().lookup_object('heater').setup_heater(config)
+    pheaters = config.get_printer().try_load_module(config, 'heaters')
+    return pheaters.setup_heater(config)
diff --git a/klippy/extras/heaters.py b/klippy/extras/heaters.py
new file mode 100644
index 00000000..29fb5d6e
--- /dev/null
+++ b/klippy/extras/heaters.py
@@ -0,0 +1,327 @@
+# Tracking of PWM controlled heaters and their temperature control
+#
+# Copyright (C) 2016-2020  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import logging, threading
+
+
+######################################################################
+# Heater
+######################################################################
+
+KELVIN_TO_CELSIUS = -273.15
+MAX_HEAT_TIME = 5.0
+AMBIENT_TEMP = 25.
+PID_PARAM_BASE = 255.
+
+class Heater:
+    def __init__(self, config, sensor):
+        self.printer = config.get_printer()
+        self.gcode = self.printer.lookup_object("gcode")
+        self.name = config.get_name().split()[-1]
+        # Setup sensor
+        self.sensor = sensor
+        self.min_temp = config.getfloat('min_temp', minval=KELVIN_TO_CELSIUS)
+        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 = (self.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 = self.smoothed_temp = self.target_temp = 0.
+        self.last_temp_time = 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 = self.printer.lookup_object('pins')
+        if algo is ControlBangBang and self.max_power == 1.:
+            self.mcu_pwm = ppins.setup_pin('digital_out', heater_pin)
+        else:
+            self.mcu_pwm = ppins.setup_pin('pwm', heater_pin)
+            pwm_cycle_time = config.getfloat(
+                '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)
+        # Load additional modules
+        self.printer.try_load_module(config, "verify_heater %s" % (self.name,))
+        self.printer.try_load_module(config, "pid_calibrate")
+        self.gcode.register_mux_command(
+            "SET_HEATER_TEMPERATURE", "HEATER", self.name,
+            self.cmd_SET_HEATER_TEMPERATURE,
+            desc=self.cmd_SET_HEATER_TEMPERATURE_help)
+    def set_pwm(self, read_time, value):
+        if self.target_temp <= 0.:
+            value = 0.
+        if ((read_time < self.next_pwm_time or not self.last_pwm_value)
+            and abs(value - self.last_pwm_value) < 0.05):
+            # No significant change in value - can suppress update
+            return
+        pwm_time = read_time + self.pwm_delay
+        self.next_pwm_time = pwm_time + 0.75 * MAX_HEAT_TIME
+        self.last_pwm_value = value
+        logging.debug("%s: pwm=%.3f@%.3f (from %.3f@%.3f [%.3f])",
+                      self.name, value, pwm_time,
+                      self.last_temp, self.last_temp_time, self.target_temp)
+        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.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, degrees):
+        if degrees and (degrees < self.min_temp or degrees > self.max_temp):
+            raise self.printer.command_error(
+                "Requested temperature (%.1f) out of range (%.1f:%.1f)"
+                % (degrees, self.min_temp, self.max_temp))
+        with self.lock:
+            self.target_temp = degrees
+    def get_temp(self, eventtime):
+        print_time = self.mcu_pwm.get_mcu().estimated_print_time(eventtime) - 5.
+        with self.lock:
+            if self.last_temp_time < print_time:
+                return 0., 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.smoothed_temp, self.target_temp)
+    def set_control(self, control):
+        with self.lock:
+            old_control = self.control
+            self.control = control
+            self.target_temp = 0.
+        return old_control
+    def alter_target(self, target_temp):
+        if target_temp:
+            target_temp = max(self.min_temp, min(self.max_temp, target_temp))
+        self.target_temp = target_temp
+    def stats(self, eventtime):
+        with self.lock:
+            target_temp = self.target_temp
+            last_temp = self.last_temp
+            last_pwm_value = self.last_pwm_value
+        is_active = target_temp or last_temp > 50.
+        return is_active, '%s: target=%.0f temp=%.1f pwm=%.3f' % (
+            self.name, target_temp, last_temp, last_pwm_value)
+    def get_status(self, eventtime):
+        with self.lock:
+            target_temp = self.target_temp
+            smoothed_temp = self.smoothed_temp
+        return {'temperature': smoothed_temp, 'target': target_temp}
+    cmd_SET_HEATER_TEMPERATURE_help = "Sets a heater temperature"
+    def cmd_SET_HEATER_TEMPERATURE(self, params):
+        temp = self.gcode.get_float('TARGET', params, 0.)
+        self.set_temp(temp)
+
+
+######################################################################
+# Bang-bang control algo
+######################################################################
+
+class ControlBangBang:
+    def __init__(self, heater, config):
+        self.heater = heater
+        self.heater_max_power = heater.get_max_power()
+        self.max_delta = config.getfloat('max_delta', 2.0, above=0.)
+        self.heating = False
+    def temperature_update(self, read_time, temp, target_temp):
+        if self.heating and temp >= target_temp+self.max_delta:
+            self.heating = False
+        elif not self.heating and temp <= target_temp-self.max_delta:
+            self.heating = True
+        if self.heating:
+            self.heater.set_pwm(read_time, self.heater_max_power)
+        else:
+            self.heater.set_pwm(read_time, 0.)
+    def check_busy(self, eventtime, smoothed_temp, target_temp):
+        return smoothed_temp < target_temp-self.max_delta
+
+
+######################################################################
+# Proportional Integral Derivative (PID) control algo
+######################################################################
+
+PID_SETTLE_DELTA = 1.
+PID_SETTLE_SLOPE = .1
+
+class ControlPID:
+    def __init__(self, heater, config):
+        self.heater = heater
+        self.heater_max_power = heater.get_max_power()
+        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 = heater.get_smooth_time()
+        imax = config.getfloat('pid_integral_max', self.heater_max_power,
+                               minval=0.)
+        self.temp_integ_max = imax / self.Ki
+        self.prev_temp = AMBIENT_TEMP
+        self.prev_temp_time = 0.
+        self.prev_temp_deriv = 0.
+        self.prev_temp_integ = 0.
+    def temperature_update(self, read_time, temp, target_temp):
+        time_diff = read_time - self.prev_temp_time
+        # Calculate change of temperature
+        temp_diff = temp - self.prev_temp
+        if time_diff >= self.min_deriv_time:
+            temp_deriv = temp_diff / time_diff
+        else:
+            temp_deriv = (self.prev_temp_deriv * (self.min_deriv_time-time_diff)
+                          + temp_diff) / self.min_deriv_time
+        # Calculate accumulated temperature "error"
+        temp_err = target_temp - temp
+        temp_integ = self.prev_temp_integ + temp_err * time_diff
+        temp_integ = max(0., min(self.temp_integ_max, temp_integ))
+        # Calculate output
+        co = self.Kp*temp_err + self.Ki*temp_integ - self.Kd*temp_deriv
+        #logging.debug("pid: %f@%.3f -> diff=%f deriv=%f err=%f integ=%f co=%d",
+        #    temp, read_time, temp_diff, temp_deriv, temp_err, temp_integ, co)
+        bounded_co = max(0., min(self.heater_max_power, co))
+        self.heater.set_pwm(read_time, bounded_co)
+        # Store state for next measurement
+        self.prev_temp = temp
+        self.prev_temp_time = read_time
+        self.prev_temp_deriv = temp_deriv
+        if co == bounded_co:
+            self.prev_temp_integ = temp_integ
+    def check_busy(self, eventtime, smoothed_temp, target_temp):
+        temp_diff = target_temp - smoothed_temp
+        return (abs(temp_diff) > PID_SETTLE_DELTA
+                or abs(self.prev_temp_deriv) > PID_SETTLE_SLOPE)
+
+
+######################################################################
+# Sensor and heater lookup
+######################################################################
+
+class PrinterHeaters:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.sensor_factories = {}
+        self.heaters = {}
+        self.gcode_id_to_sensor = {}
+        self.available_heaters = []
+        self.available_sensors = []
+        self.has_started = False
+        self.printer.register_event_handler("klippy:ready", self._handle_ready)
+        self.printer.register_event_handler("gcode:request_restart",
+                                            self.turn_off_all_heaters)
+        # Register commands
+        gcode = self.printer.lookup_object('gcode')
+        gcode.register_command("TURN_OFF_HEATERS", self.cmd_TURN_OFF_HEATERS,
+                               desc=self.cmd_TURN_OFF_HEATERS_help)
+        gcode.register_command("M105", self.cmd_M105, when_not_ready=True)
+    def add_sensor_factory(self, sensor_type, sensor_factory):
+        self.sensor_factories[sensor_type] = sensor_factory
+    def setup_heater(self, config, gcode_id=None):
+        heater_name = config.get_name().split()[-1]
+        if heater_name in self.heaters:
+            raise config.error("Heater %s already registered" % (heater_name,))
+        # Setup sensor
+        sensor = self.setup_sensor(config)
+        # Create heater
+        self.heaters[heater_name] = heater = Heater(config, sensor)
+        self.register_sensor(config, heater, gcode_id)
+        self.available_heaters.append(config.get_name())
+        return heater
+    def get_all_heaters(self):
+        return self.available_heaters
+    def lookup_heater(self, heater_name):
+        if heater_name not in self.heaters:
+            raise self.printer.config_error(
+                "Unknown heater '%s'" % (heater_name,))
+        return self.heaters[heater_name]
+    def setup_sensor(self, config):
+        self.printer.try_load_module(config, "thermistor")
+        self.printer.try_load_module(config, "adc_temperature")
+        self.printer.try_load_module(config, "spi_temperature")
+        self.printer.try_load_module(config, "bme280")
+        sensor_type = config.get('sensor_type')
+        if sensor_type not in self.sensor_factories:
+            raise self.printer.config_error(
+                "Unknown temperature sensor '%s'" % (sensor_type,))
+        return self.sensor_factories[sensor_type](config)
+    def register_sensor(self, config, psensor, gcode_id=None):
+        if gcode_id is None:
+            gcode_id = config.get('gcode_id', None)
+            if gcode_id is None:
+                return
+        if gcode_id in self.gcode_id_to_sensor:
+            raise self.printer.config_error(
+                "G-Code sensor id %s already registered" % (gcode_id,))
+        self.gcode_id_to_sensor[gcode_id] = psensor
+        self.available_sensors.append(config.get_name())
+    def get_status(self, eventtime):
+        return {'available_heaters': self.available_heaters,
+                'available_sensors': self.available_sensors}
+    def turn_off_all_heaters(self, print_time=0.):
+        for heater in self.heaters.values():
+            heater.set_temp(0.)
+    cmd_TURN_OFF_HEATERS_help = "Turn off all heaters"
+    def cmd_TURN_OFF_HEATERS(self, params):
+        self.turn_off_all_heaters()
+    # G-Code M105 temperature reporting
+    def _handle_ready(self):
+        self.has_started = True
+    def _get_temp(self, eventtime):
+        # Tn:XXX /YYY B:XXX /YYY
+        out = []
+        if self.has_started:
+            for gcode_id, sensor in sorted(self.gcode_id_to_sensor.items()):
+                cur, target = sensor.get_temp(eventtime)
+                out.append("%s:%.1f /%.1f" % (gcode_id, cur, target))
+        if not out:
+            return "T:0"
+        return " ".join(out)
+    def cmd_M105(self, params):
+        # Get Extruder Temperature
+        gcode = self.printer.lookup_object("gcode")
+        reactor = self.printer.get_reactor()
+        msg = self._get_temp(reactor.monotonic())
+        did_ack = gcode.ack(msg)
+        if not did_ack:
+            gcode.respond_raw(msg)
+    def wait_for_temperature(self, heater):
+        # Helper to wait on heater.check_busy() and report M105 temperatures
+        if self.printer.get_start_args().get('debugoutput') is not None:
+            return
+        toolhead = self.printer.lookup_object("toolhead")
+        gcode = self.printer.lookup_object("gcode")
+        reactor = self.printer.get_reactor()
+        eventtime = reactor.monotonic()
+        while not self.printer.is_shutdown() and heater.check_busy(eventtime):
+            print_time = toolhead.get_last_move_time()
+            gcode.respond_raw(self._get_temp(eventtime))
+            eventtime = reactor.pause(eventtime + 1.)
+
+def load_config(config):
+    return PrinterHeaters(config)
diff --git a/klippy/extras/homing_heaters.py b/klippy/extras/homing_heaters.py
index 6433869f..673b7f8d 100644
--- a/klippy/extras/homing_heaters.py
+++ b/klippy/extras/homing_heaters.py
@@ -19,12 +19,12 @@ class HomingHeaters:
         self.disable_heaters = []
         self.steppers_needing_quiet = config.get("steppers", "")
         self.flaky_steppers = []
-        self.pheater = self.printer.lookup_object('heater')
+        self.pheaters = self.printer.try_load_module(config, 'heaters')
         self.target_save = {}
 
     def handle_connect(self):
         # heaters to disable
-        all_heaters = self.pheater.get_all_heaters()
+        all_heaters = self.pheaters.get_all_heaters()
         self.disable_heaters = [n.strip()
                           for n in self.heaters_to_disable.split(',')]
         if self.disable_heaters == [""]:
@@ -56,14 +56,14 @@ class HomingHeaters:
         if not self.check_eligible(endstops):
             return
         for heater_name in self.disable_heaters:
-            heater = self.pheater.lookup_heater(heater_name)
+            heater = self.pheaters.lookup_heater(heater_name)
             self.target_save[heater_name] = heater.get_temp(0)[1]
             heater.set_temp(0.)
     def handle_homing_move_end(self, endstops):
         if not self.check_eligible(endstops):
             return
         for heater_name in self.disable_heaters:
-            heater = self.pheater.lookup_heater(heater_name)
+            heater = self.pheaters.lookup_heater(heater_name)
             heater.set_temp(self.target_save[heater_name])
 
 def load_config(config):
diff --git a/klippy/extras/pid_calibrate.py b/klippy/extras/pid_calibrate.py
index 49ae3bb4..b5dbc773 100644
--- a/klippy/extras/pid_calibrate.py
+++ b/klippy/extras/pid_calibrate.py
@@ -18,9 +18,9 @@ class PIDCalibrate:
         heater_name = self.gcode.get_str('HEATER', params)
         target = self.gcode.get_float('TARGET', params)
         write_file = self.gcode.get_int('WRITE_FILE', params, 0)
-        pheater = self.printer.lookup_object('heater')
+        pheaters = self.printer.lookup_object('heaters')
         try:
-            heater = pheater.lookup_heater(heater_name)
+            heater = pheaters.lookup_heater(heater_name)
         except self.printer.config_error as e:
             raise self.gcode.error(str(e))
         self.printer.lookup_object('toolhead').get_last_move_time()
@@ -31,7 +31,7 @@ class PIDCalibrate:
         except self.printer.command_error as e:
             heater.set_control(old_control)
             raise
-        pheater.wait_for_temperature(heater)
+        pheaters.wait_for_temperature(heater)
         heater.set_control(old_control)
         if write_file:
             calibrate.write_file('/tmp/heattest.txt')
diff --git a/klippy/extras/spi_temperature.py b/klippy/extras/spi_temperature.py
index 74cf9505..606a317e 100644
--- a/klippy/extras/spi_temperature.py
+++ b/klippy/extras/spi_temperature.py
@@ -336,6 +336,6 @@ Sensors = {
 
 def load_config(config):
     # Register sensors
-    pheater = config.get_printer().lookup_object("heater")
+    pheaters = config.get_printer().try_load_module(config, "heaters")
     for name, klass in Sensors.items():
-        pheater.add_sensor_factory(name, klass)
+        pheaters.add_sensor_factory(name, klass)
diff --git a/klippy/extras/temperature_fan.py b/klippy/extras/temperature_fan.py
index 6fc2893b..cebeee1f 100644
--- a/klippy/extras/temperature_fan.py
+++ b/klippy/extras/temperature_fan.py
@@ -18,10 +18,11 @@ class TemperatureFan:
         self.gcode = self.printer.lookup_object('gcode')
         self.min_temp = config.getfloat('min_temp', minval=KELVIN_TO_CELSIUS)
         self.max_temp = config.getfloat('max_temp', above=self.min_temp)
-        self.sensor = self.printer.lookup_object('heater').setup_sensor(config)
+        pheaters = self.printer.try_load_module(config, 'heaters')
+        self.sensor = pheaters.setup_sensor(config)
         self.sensor.setup_minmax(self.min_temp, self.max_temp)
         self.sensor.setup_callback(self.temperature_callback)
-        self.printer.lookup_object('heater').register_sensor(config, self)
+        pheaters.register_sensor(config, self)
         self.speed_delay = self.sensor.get_report_time_delta()
         self.max_speed = config.getfloat('max_speed', 1., above=0., maxval=1.)
         self.min_speed = config.getfloat('min_speed', 0.3, minval=0., maxval=1.)
diff --git a/klippy/extras/temperature_sensor.py b/klippy/extras/temperature_sensor.py
index 62b7afef..94779a85 100644
--- a/klippy/extras/temperature_sensor.py
+++ b/klippy/extras/temperature_sensor.py
@@ -9,14 +9,15 @@ KELVIN_TO_CELSIUS = -273.15
 class PrinterSensorGeneric:
     def __init__(self, config):
         self.printer = config.get_printer()
-        self.sensor = self.printer.lookup_object('heater').setup_sensor(config)
+        pheaters = self.printer.try_load_module(config, 'heaters')
+        self.sensor = pheaters.setup_sensor(config)
         self.min_temp = config.getfloat('min_temp', KELVIN_TO_CELSIUS,
                                         minval=KELVIN_TO_CELSIUS)
         self.max_temp = config.getfloat('max_temp', 99999999.9,
                                         above=self.min_temp)
         self.sensor.setup_minmax(self.min_temp, self.max_temp)
         self.sensor.setup_callback(self.temperature_callback)
-        self.printer.lookup_object('heater').register_sensor(config, self)
+        pheaters.register_sensor(config, self)
         self.last_temp = 0.
     def temperature_callback(self, read_time, temp):
         self.last_temp = temp
diff --git a/klippy/extras/thermistor.py b/klippy/extras/thermistor.py
index f43c0a99..7e3aa3aa 100644
--- a/klippy/extras/thermistor.py
+++ b/klippy/extras/thermistor.py
@@ -116,12 +116,12 @@ Sensors = {
 
 def load_config(config):
     # Register default thermistor types
-    pheater = config.get_printer().lookup_object("heater")
+    pheaters = config.get_printer().try_load_module(config, "heaters")
     for sensor_type, params in Sensors.items():
         func = (lambda config, params=params: PrinterThermistor(config, params))
-        pheater.add_sensor_factory(sensor_type, func)
+        pheaters.add_sensor_factory(sensor_type, func)
 
 def load_config_prefix(config):
     thermistor = CustomThermistor(config)
-    pheater = config.get_printer().lookup_object("heater")
-    pheater.add_sensor_factory(thermistor.name, thermistor.create)
+    pheaters = config.get_printer().try_load_module(config, "heaters")
+    pheaters.add_sensor_factory(thermistor.name, thermistor.create)
diff --git a/klippy/extras/verify_heater.py b/klippy/extras/verify_heater.py
index a76646f5..8c5360d5 100644
--- a/klippy/extras/verify_heater.py
+++ b/klippy/extras/verify_heater.py
@@ -35,8 +35,8 @@ class HeaterCheck:
         if self.printer.get_start_args().get('debugoutput') is not None:
             # Disable verify_heater if outputting to a debug file
             return
-        pheater = self.printer.lookup_object('heater')
-        self.heater = pheater.lookup_heater(self.heater_name)
+        pheaters = self.printer.lookup_object('heaters')
+        self.heater = pheaters.lookup_heater(self.heater_name)
         logging.info("Starting heater checks for %s", self.heater_name)
         reactor = self.printer.get_reactor()
         self.check_timer = reactor.register_timer(self.check_event, reactor.NOW)