229 lines
9.6 KiB
Python
229 lines
9.6 KiB
Python
# Printer heater support
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#
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# Copyright (C) 2016-2018 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import logging, threading
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######################################################################
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# Heater
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######################################################################
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KELVIN_TO_CELCIUS = -273.15
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MAX_HEAT_TIME = 5.0
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AMBIENT_TEMP = 25.
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PID_PARAM_BASE = 255.
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class error(Exception):
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pass
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class Heater:
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error = error
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def __init__(self, config, sensor):
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self.sensor = sensor
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self.name = config.get_name()
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printer = config.get_printer()
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self.min_temp = config.getfloat('min_temp', minval=KELVIN_TO_CELCIUS)
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self.max_temp = config.getfloat('max_temp', above=self.min_temp)
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self.sensor.setup_minmax(self.min_temp, self.max_temp)
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self.sensor.setup_callback(self.temperature_callback)
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self.pwm_delay = self.sensor.get_report_time_delta()
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self.min_extrude_temp = config.getfloat(
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'min_extrude_temp', 170., minval=self.min_temp, maxval=self.max_temp)
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self.max_power = config.getfloat('max_power', 1., above=0., maxval=1.)
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self.lock = threading.Lock()
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self.last_temp = 0.
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self.last_temp_time = 0.
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self.target_temp = 0.
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algos = {'watermark': ControlBangBang, 'pid': ControlPID}
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algo = config.getchoice('control', algos)
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heater_pin = config.get('heater_pin')
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ppins = printer.lookup_object('pins')
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if algo is ControlBangBang and self.max_power == 1.:
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self.mcu_pwm = ppins.setup_pin('digital_out', heater_pin)
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else:
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self.mcu_pwm = ppins.setup_pin('pwm', heater_pin)
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pwm_cycle_time = config.getfloat(
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'pwm_cycle_time', 0.100, above=0., maxval=self.pwm_delay)
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self.mcu_pwm.setup_cycle_time(pwm_cycle_time)
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self.mcu_pwm.setup_max_duration(MAX_HEAT_TIME)
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is_fileoutput = self.mcu_pwm.get_mcu().is_fileoutput()
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self.can_extrude = self.min_extrude_temp <= 0. or is_fileoutput
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self.control = algo(self, config)
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# pwm caching
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self.next_pwm_time = 0.
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self.last_pwm_value = 0.
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# Load additional modules
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printer.try_load_module(config, "verify_heater %s" % (self.name,))
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printer.try_load_module(config, "pid_calibrate")
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def set_pwm(self, read_time, value):
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if self.target_temp <= 0.:
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value = 0.
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if ((read_time < self.next_pwm_time or not self.last_pwm_value)
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and abs(value - self.last_pwm_value) < 0.05):
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# No significant change in value - can suppress update
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return
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pwm_time = read_time + self.pwm_delay
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self.next_pwm_time = pwm_time + 0.75 * MAX_HEAT_TIME
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self.last_pwm_value = value
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logging.debug("%s: pwm=%.3f@%.3f (from %.3f@%.3f [%.3f])",
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self.name, value, pwm_time,
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self.last_temp, self.last_temp_time, self.target_temp)
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self.mcu_pwm.set_pwm(pwm_time, value)
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def temperature_callback(self, read_time, temp):
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with self.lock:
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self.last_temp = temp
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self.last_temp_time = read_time
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self.can_extrude = (temp >= self.min_extrude_temp)
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self.control.temperature_callback(read_time, temp)
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#logging.debug("temp: %.3f %f = %f", read_time, temp)
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# External commands
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def set_temp(self, print_time, degrees):
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if degrees and (degrees < self.min_temp or degrees > self.max_temp):
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raise error("Requested temperature (%.1f) out of range (%.1f:%.1f)"
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% (degrees, self.min_temp, self.max_temp))
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with self.lock:
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self.target_temp = degrees
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def get_temp(self, eventtime):
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print_time = self.mcu_pwm.get_mcu().estimated_print_time(eventtime) - 5.
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with self.lock:
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if self.last_temp_time < print_time:
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return 0., self.target_temp
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return self.last_temp, self.target_temp
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def check_busy(self, eventtime):
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with self.lock:
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return self.control.check_busy(eventtime)
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def set_control(self, control):
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with self.lock:
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old_control = self.control
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self.control = control
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self.target_temp = 0.
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return old_control
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def stats(self, eventtime):
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with self.lock:
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target_temp = self.target_temp
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last_temp = self.last_temp
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last_pwm_value = self.last_pwm_value
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is_active = target_temp or last_temp > 50.
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return is_active, '%s: target=%.0f temp=%.1f pwm=%.3f' % (
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self.name, target_temp, last_temp, last_pwm_value)
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def get_status(self, eventtime):
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with self.lock:
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target_temp = self.target_temp
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last_temp = self.last_temp
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return {'temperature': last_temp, 'target': target_temp}
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######################################################################
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# Bang-bang control algo
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######################################################################
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class ControlBangBang:
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def __init__(self, heater, config):
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self.heater = heater
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self.max_delta = config.getfloat('max_delta', 2.0, above=0.)
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self.heating = False
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def temperature_callback(self, read_time, temp):
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if self.heating and temp >= self.heater.target_temp+self.max_delta:
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self.heating = False
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elif not self.heating and temp <= self.heater.target_temp-self.max_delta:
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self.heating = True
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if self.heating:
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self.heater.set_pwm(read_time, self.heater.max_power)
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else:
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self.heater.set_pwm(read_time, 0.)
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def check_busy(self, eventtime):
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return self.heater.last_temp < self.heater.target_temp-self.max_delta
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######################################################################
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# Proportional Integral Derivative (PID) control algo
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######################################################################
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PID_SETTLE_DELTA = 1.
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PID_SETTLE_SLOPE = .1
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class ControlPID:
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def __init__(self, heater, config):
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self.heater = heater
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self.Kp = config.getfloat('pid_Kp') / PID_PARAM_BASE
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self.Ki = config.getfloat('pid_Ki') / PID_PARAM_BASE
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self.Kd = config.getfloat('pid_Kd') / PID_PARAM_BASE
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self.min_deriv_time = config.getfloat('pid_deriv_time', 2., above=0.)
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imax = config.getfloat('pid_integral_max', heater.max_power, minval=0.)
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self.temp_integ_max = imax / self.Ki
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self.prev_temp = AMBIENT_TEMP
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self.prev_temp_time = 0.
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self.prev_temp_deriv = 0.
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self.prev_temp_integ = 0.
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def temperature_callback(self, read_time, temp):
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time_diff = read_time - self.prev_temp_time
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# Calculate change of temperature
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temp_diff = temp - self.prev_temp
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if time_diff >= self.min_deriv_time:
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temp_deriv = temp_diff / time_diff
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else:
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temp_deriv = (self.prev_temp_deriv * (self.min_deriv_time-time_diff)
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+ temp_diff) / self.min_deriv_time
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# Calculate accumulated temperature "error"
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temp_err = self.heater.target_temp - temp
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temp_integ = self.prev_temp_integ + temp_err * time_diff
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temp_integ = max(0., min(self.temp_integ_max, temp_integ))
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# Calculate output
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co = self.Kp*temp_err + self.Ki*temp_integ - self.Kd*temp_deriv
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#logging.debug("pid: %f@%.3f -> diff=%f deriv=%f err=%f integ=%f co=%d",
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# temp, read_time, temp_diff, temp_deriv, temp_err, temp_integ, co)
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bounded_co = max(0., min(self.heater.max_power, co))
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self.heater.set_pwm(read_time, bounded_co)
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# Store state for next measurement
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self.prev_temp = temp
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self.prev_temp_time = read_time
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self.prev_temp_deriv = temp_deriv
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if co == bounded_co:
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self.prev_temp_integ = temp_integ
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def check_busy(self, eventtime):
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temp_diff = self.heater.target_temp - self.heater.last_temp
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return (abs(temp_diff) > PID_SETTLE_DELTA
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or abs(self.prev_temp_deriv) > PID_SETTLE_SLOPE)
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######################################################################
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# Sensor and heater lookup
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######################################################################
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class PrinterHeaters:
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def __init__(self, printer, config):
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self.printer = printer
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self.sensors = {}
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self.heaters = {}
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def add_sensor(self, sensor_type, sensor_factory):
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self.sensors[sensor_type] = sensor_factory
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def setup_heater(self, config):
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heater_name = config.get_name()
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if heater_name == 'extruder':
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heater_name = 'extruder0'
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if heater_name in self.heaters:
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raise config.error("Heater %s already registered" % (heater_name,))
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# Setup sensor
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self.printer.try_load_module(config, "thermistor")
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self.printer.try_load_module(config, "adc_temperature")
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sensor_type = config.get('sensor_type')
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if sensor_type not in self.sensors:
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raise self.printer.config_error("Unknown temperature sensor '%s'" % (
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sensor_type,))
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sensor = self.sensors[sensor_type](config)
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# Create heater
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self.heaters[heater_name] = heater = Heater(config, sensor)
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return heater
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def lookup_heater(self, heater_name):
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if heater_name == 'extruder':
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heater_name = 'extruder0'
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if heater_name not in self.heaters:
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raise self.printer.config_error(
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"Unknown heater '%s'" % (heater_name,))
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return self.heaters[heater_name]
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def add_printer_objects(printer, config):
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printer.add_object('heater', PrinterHeaters(printer, config))
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