123 lines
5.3 KiB
Python
123 lines
5.3 KiB
Python
# Obtain temperature using linear interpolation of ADC values
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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, bisect
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SAMPLE_TIME = 0.001
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SAMPLE_COUNT = 8
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REPORT_TIME = 0.300
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RANGE_CHECK_COUNT = 4
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# Linear style conversion chips calibrated with two temp measurements
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class Linear:
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def __init__(self, config, params):
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ppins = config.get_printer().lookup_object('pins')
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self.mcu_adc = ppins.setup_pin('adc', config.get('sensor_pin'))
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self.mcu_adc.setup_adc_callback(REPORT_TIME, self.adc_callback)
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self.temperature_callback = None
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self.adc_samples = []
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self.slope_samples = []
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self.calc_coefficients(config, params)
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def calc_coefficients(self, config, params):
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adc_voltage = config.getfloat('adc_voltage', 5., above=0.)
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last_volt = last_temp = None
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for volt, temp in sorted([(v, t) for t, v in params]):
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adc = volt / adc_voltage
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if adc < 0. or adc > 1.:
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logging.warn("Ignoring adc sample %.3f/%.3f in heater %s",
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temp, volt, config.get_name())
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continue
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if last_volt is None:
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last_volt = volt
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last_temp = temp
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continue
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if volt <= last_volt:
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raise config.error("adc_temperature duplicate voltage")
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slope = (temp - last_temp) / (volt - last_volt)
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gain = adc_voltage * slope
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offset = last_temp - last_volt * slope
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if self.slope_samples and self.slope_samples[-1] == (gain, offset):
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continue
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last_temp = temp
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last_volt = volt
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self.adc_samples.append(adc)
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self.slope_samples.append((gain, offset))
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if not self.adc_samples:
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raise config.error(
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"adc_temperature needs two volt and temperature measurements")
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self.adc_samples[-1] = 1.
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def setup_minmax(self, min_temp, max_temp):
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adc_range = [self.calc_adc(min_temp), self.calc_adc(max_temp)]
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self.mcu_adc.setup_minmax(SAMPLE_TIME, SAMPLE_COUNT,
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minval=min(adc_range), maxval=max(adc_range),
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range_check_count=RANGE_CHECK_COUNT)
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def setup_callback(self, temperature_callback):
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self.temperature_callback = temperature_callback
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def get_report_time_delta(self):
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return REPORT_TIME
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def adc_callback(self, read_time, read_value):
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pos = bisect.bisect(self.adc_samples, read_value)
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gain, offset = self.slope_samples[pos]
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temp = read_value * gain + offset
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self.temperature_callback(read_time + SAMPLE_COUNT * SAMPLE_TIME, temp)
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def calc_adc(self, temp):
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temps = [adc * gain + offset for adc, (gain, offset) in zip(
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self.adc_samples, self.slope_samples)]
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if temps[0] < temps[-1]:
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pos = min([i for i in range(len(temps)) if temps[i] >= temp]
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+ [len(temps) - 1])
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else:
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pos = min([i for i in range(len(temps)) if temps[i] <= temp]
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+ [len(temps) - 1])
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gain, offset = self.slope_samples[pos]
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return (temp - offset) / gain
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# Custom defined sensors from the config file
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class CustomLinear:
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def __init__(self, config):
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self.name = " ".join(config.get_name().split()[1:])
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self.params = []
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for i in range(1, 1000):
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t = config.getfloat("temperature%d" % (i,), None)
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if t is None:
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break
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v = config.getfloat("voltage%d" % (i,))
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self.params.append((t, v))
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def create(self, config):
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return Linear(config, self.params)
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AD595 = [
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(0., .0027), (10., .101), (20., .200), (25., .250), (30., .300), (40., .401),
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(50., .503), (60., .605), (80., .810), (100., 1.015), (120., 1.219),
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(140., 1.420), (160., 1.620), (180., 1.817), (200., 2.015), (220., 2.213),
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(240., 2.413), (260., 2.614), (280., 2.817), (300., 3.022), (320., 3.227),
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(340., 3.434), (360., 3.641), (380., 3.849), (400., 4.057), (420., 4.266),
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(440., 4.476), (460., 4.686), (480., 4.896)
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]
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PT100 = [
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(0, 0.00), (1, 1.11), (10, 1.15), (20, 1.20), (30, 1.24), (40, 1.28),
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(50, 1.32), (60, 1.36), (70, 1.40), (80, 1.44), (90, 1.48), (100, 1.52),
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(110, 1.56), (120, 1.61), (130, 1.65), (140, 1.68), (150, 1.72), (160, 1.76),
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(170, 1.80), (180, 1.84), (190, 1.88), (200, 1.92), (210, 1.96), (220, 2.00),
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(230, 2.04), (240, 2.07), (250, 2.11), (260, 2.15), (270, 2.18), (280, 2.22),
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(290, 2.26), (300, 2.29), (310, 2.33), (320, 2.37), (330, 2.41), (340, 2.44),
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(350, 2.48), (360, 2.51), (370, 2.55), (380, 2.58), (390, 2.62), (400, 2.66),
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(500, 3.00), (600, 3.33), (700, 3.63), (800, 3.93), (900, 4.21),
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(1000, 4.48), (1100, 4.73)
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]
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def load_config(config):
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# Register default sensors
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pheater = config.get_printer().lookup_object("heater")
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for sensor_type, params in [("AD595", AD595), ("PT100 INA826", PT100)]:
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func = (lambda config, params=params: Linear(config, params))
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pheater.add_sensor(sensor_type, func)
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def load_config_prefix(config):
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linear = CustomLinear(config)
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pheater = config.get_printer().lookup_object("heater")
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pheater.add_sensor(linear.name, linear.create)
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