diff options
Diffstat (limited to 'klippy/heater.py')
| -rw-r--r-- | klippy/heater.py | 113 |
1 files changed, 70 insertions, 43 deletions
diff --git a/klippy/heater.py b/klippy/heater.py index a2b8a7fa..8d1e658e 100644 --- a/klippy/heater.py +++ b/klippy/heater.py @@ -1,28 +1,83 @@ # Printer heater support # -# Copyright (C) 2016 Kevin O'Connor <kevin@koconnor.net> +# Copyright (C) 2016,2017 Kevin O'Connor <kevin@koconnor.net> # # This file may be distributed under the terms of the GNU GPLv3 license. import math, logging, threading + +###################################################################### +# Sensors +###################################################################### + +KELVIN_TO_CELCIUS = -273.15 + +# Thermistor calibrated with three temp measurements +class Thermistor: + def __init__(self, config, params): + self.pullup = config.getfloat('pullup_resistor', 4700., above=0.) + # Calculate Steinhart-Hart coefficents from temp measurements + inv_t1 = 1. / (params['t1'] - KELVIN_TO_CELCIUS) + inv_t2 = 1. / (params['t2'] - KELVIN_TO_CELCIUS) + inv_t3 = 1. / (params['t3'] - KELVIN_TO_CELCIUS) + ln_r1 = math.log(params['r1']) + ln_r2 = math.log(params['r2']) + ln_r3 = math.log(params['r3']) + ln3_r1, ln3_r2, ln3_r3 = ln_r1**3., ln_r2**3., ln_r3**3. + + inv_t12, inv_t13 = inv_t1-inv_t2, inv_t1 - inv_t3 + ln_r12, ln_r13 = ln_r1 - ln_r2, ln_r1 - ln_r3 + ln3_r12, ln3_r13 = ln3_r1 - ln3_r2, ln3_r1 - ln3_r3 + + self.c3 = ((inv_t12 - inv_t13 * ln_r12 / ln_r13) + / (ln3_r12 - ln3_r13 * ln_r12 / ln_r13)) + self.c2 = (inv_t12 - self.c3 * ln3_r12) / ln_r12 + self.c1 = inv_t1 - self.c3 * ln3_r1 - self.c2 * ln_r1 + def calc_temp(self, adc): + r = self.pullup * adc / (1.0 - adc) + ln_r = math.log(r) + temp_inv = self.c1 + self.c2*ln_r + self.c3*math.pow(ln_r, 3.) + return 1.0/temp_inv + KELVIN_TO_CELCIUS + def calc_adc(self, temp): + temp -= KELVIN_TO_CELCIUS + temp_inv = 1./temp + y = (self.c1 - temp_inv) / (2. * self.c3) + x = math.sqrt(math.pow(self.c2 / (3.*self.c3), 3.) + math.pow(y, 2.)) + r = math.exp(math.pow(x-y, 1./3.) - math.pow(x+y, 1./3.)) + return r / (self.pullup + r) + +# Linear style conversion chips calibrated with two temp measurements +class Linear: + def __init__(self, config, params): + adc_voltage = config.getfloat('adc_voltage', 5., above=0.) + slope = (params['t2'] - params['t1']) / (params['v2'] - params['v1']) + self.gain = adc_voltage * slope + self.offset = params['t1'] - params['v1'] * slope + def calc_temp(self, adc): + return adc * self.gain + self.offset + def calc_adc(self, temp): + return (temp - self.offset) / self.gain + # Available sensors Sensors = { - # Common thermistors and their Steinhart-Hart coefficients - "EPCOS 100K B57560G104F": ( - "thermistor", - 0.000722136308968056, 0.000216766566488498, 8.92935804531095e-08), - "ATC Semitec 104GT-2": ( - "thermistor", - 0.000809651054275124, 0.000211636030735685, 7.07420883993973e-08), - # Linear style conversion chips and their gain/offset - "AD595": ("linear", 300.0 / 3.022, 0.), + "EPCOS 100K B57560G104F": { + 'class': Thermistor, 't1': 25., 'r1': 100000., + 't2': 150., 'r2': 1641.9, 't3': 250., 'r3': 226.15 }, + "ATC Semitec 104GT-2": { + 'class': Thermistor, 't1': 20., 'r1': 126800., + 't2': 150., 'r2': 1360., 't3': 300., 'r3': 80.65 }, + "AD595": { 'class': Linear, 't1': 25., 'v1': .25, 't2': 300., 'v2': 3.022 }, } + +###################################################################### +# Heater +###################################################################### + SAMPLE_TIME = 0.001 SAMPLE_COUNT = 8 REPORT_TIME = 0.300 PWM_CYCLE_TIME = 0.100 -KELVIN_TO_CELCIUS = -273.15 MAX_HEAT_TIME = 5.0 AMBIENT_TEMP = 25. PID_PARAM_BASE = 255. @@ -35,13 +90,7 @@ class PrinterHeater: def __init__(self, printer, config): self.name = config.section sensor_params = config.getchoice('sensor_type', Sensors) - self.is_linear_sensor = (sensor_params[0] == 'linear') - if self.is_linear_sensor: - adc_voltage = config.getfloat('adc_voltage', 5., above=0.) - self.sensor_coef = sensor_params[1] * adc_voltage, sensor_params[2] - else: - pullup = config.getfloat('pullup_resistor', 4700., above=0.) - self.sensor_coef = sensor_params[1:] + (pullup,) + self.sensor = sensor_params['class'](config, sensor_params) self.min_temp = config.getfloat('min_temp', minval=0.) self.max_temp = config.getfloat('max_temp', above=self.min_temp) self.min_extrude_temp = config.getfloat( @@ -64,7 +113,8 @@ class PrinterHeater: self.mcu_pwm = printer.mcu.create_pwm( heater_pin, PWM_CYCLE_TIME, 0, MAX_HEAT_TIME) self.mcu_adc = printer.mcu.create_adc(sensor_pin) - adc_range = [self.calc_adc(self.min_temp), self.calc_adc(self.max_temp)] + adc_range = [self.sensor.calc_adc(self.min_temp), + self.sensor.calc_adc(self.max_temp)] self.mcu_adc.set_minmax(SAMPLE_TIME, SAMPLE_COUNT, minval=min(adc_range), maxval=max(adc_range)) self.mcu_adc.set_adc_callback(REPORT_TIME, self.adc_callback) @@ -86,31 +136,8 @@ class PrinterHeater: self.name, value, pwm_time, self.last_temp, self.last_temp_time, self.target_temp)) self.mcu_pwm.set_pwm(pwm_time, value) - # Temperature calculation - def calc_temp(self, adc): - if self.is_linear_sensor: - gain, offset = self.sensor_coef - return adc * gain + offset - c1, c2, c3, pullup = self.sensor_coef - r = pullup * adc / (1.0 - adc) - ln_r = math.log(r) - temp_inv = c1 + c2*ln_r + c3*math.pow(ln_r, 3) - return 1.0/temp_inv + KELVIN_TO_CELCIUS - def calc_adc(self, temp): - if temp is None: - return None - if self.is_linear_sensor: - gain, offset = self.sensor_coef - return (temp - offset) / gain - c1, c2, c3, pullup = self.sensor_coef - temp -= KELVIN_TO_CELCIUS - temp_inv = 1./temp - y = (c1 - temp_inv) / (2*c3) - x = math.sqrt(math.pow(c2 / (3.*c3), 3.) + math.pow(y, 2.)) - r = math.exp(math.pow(x-y, 1./3.) - math.pow(x+y, 1./3.)) - return r / (pullup + r) def adc_callback(self, read_time, read_value): - temp = self.calc_temp(read_value) + temp = self.sensor.calc_temp(read_value) with self.lock: self.last_temp = temp self.last_temp_time = read_time |