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- # Obtain temperature using linear interpolation of ADC values
- #
- # Copyright (C) 2016-2018 Kevin O'Connor <kevin@koconnor.net>
- #
- # This file may be distributed under the terms of the GNU GPLv3 license.
- import logging, bisect
- SAMPLE_TIME = 0.001
- SAMPLE_COUNT = 8
- REPORT_TIME = 0.300
- # Linear style conversion chips calibrated with two temp measurements
- class Linear:
- def __init__(self, config, params):
- ppins = config.get_printer().lookup_object('pins')
- self.mcu_adc = ppins.setup_pin('adc', config.get('sensor_pin'))
- self.mcu_adc.setup_adc_callback(REPORT_TIME, self.adc_callback)
- self.temperature_callback = None
- self.adc_samples = []
- self.slope_samples = []
- self.calc_coefficients(config, params)
- def calc_coefficients(self, config, params):
- adc_voltage = config.getfloat('adc_voltage', 5., above=0.)
- last_volt = last_temp = None
- for volt, temp in sorted([(v, t) for t, v in params]):
- adc = volt / adc_voltage
- if adc < 0. or adc > 1.:
- logging.warn("Ignoring adc sample %.3f/%.3f in heater %s",
- temp, volt, config.get_name())
- continue
- if last_volt is None:
- last_volt = volt
- last_temp = temp
- continue
- if volt <= last_volt:
- raise config.error("adc_temperature duplicate voltage")
- slope = (temp - last_temp) / (volt - last_volt)
- gain = adc_voltage * slope
- offset = last_temp - last_volt * slope
- if self.slope_samples and self.slope_samples[-1] == (gain, offset):
- continue
- last_temp = temp
- last_volt = volt
- self.adc_samples.append(adc)
- self.slope_samples.append((gain, offset))
- if not self.adc_samples:
- raise config.error(
- "adc_temperature needs two volt and temperature measurements")
- self.adc_samples[-1] = 1.
- def setup_minmax(self, min_temp, max_temp):
- adc_range = [self.calc_adc(min_temp), self.calc_adc(max_temp)]
- self.mcu_adc.setup_minmax(SAMPLE_TIME, SAMPLE_COUNT,
- minval=min(adc_range), maxval=max(adc_range))
- def setup_callback(self, temperature_callback):
- self.temperature_callback = temperature_callback
- def get_report_time_delta(self):
- return REPORT_TIME
- def adc_callback(self, read_time, read_value):
- pos = bisect.bisect(self.adc_samples, read_value)
- gain, offset = self.slope_samples[pos]
- temp = read_value * gain + offset
- logging.info("temperature=%.6f from adc=%.6f at %.6f", temp, read_value, read_time)
- self.temperature_callback(read_time + SAMPLE_COUNT * SAMPLE_TIME, temp)
- def calc_adc(self, temp):
- temps = [adc * gain + offset for adc, (gain, offset) in zip(
- self.adc_samples, self.slope_samples)]
- if temps[0] < temps[-1]:
- pos = min([i for i in range(len(temps)) if temps[i] >= temp]
- + [len(temps) - 1])
- else:
- pos = min([i for i in range(len(temps)) if temps[i] <= temp]
- + [len(temps) - 1])
- gain, offset = self.slope_samples[pos]
- return (temp - offset) / gain
- # Custom defined sensors from the config file
- class CustomLinear:
- def __init__(self, config):
- self.name = " ".join(config.get_name().split()[1:])
- self.params = []
- for i in range(1, 1000):
- t = config.getfloat("temperature%d" % (i,), None)
- if t is None:
- break
- v = config.getfloat("voltage%d" % (i,))
- self.params.append((t, v))
- def create(self, config):
- return Linear(config, self.params)
- AD595 = [
- (0., .0027), (10., .101), (20., .200), (25., .250), (30., .300), (40., .401),
- (50., .503), (60., .605), (80., .810), (100., 1.015), (120., 1.219),
- (140., 1.420), (160., 1.620), (180., 1.817), (200., 2.015), (220., 2.213),
- (240., 2.413), (260., 2.614), (280., 2.817), (300., 3.022), (320., 3.227),
- (340., 3.434), (360., 3.641), (380., 3.849), (400., 4.057), (420., 4.266),
- (440., 4.476), (460., 4.686), (480., 4.896)
- ]
- PT100 = [
- (0, 0.00), (1, 1.11), (10, 1.15), (20, 1.20), (30, 1.24), (40, 1.28),
- (50, 1.32), (60, 1.36), (70, 1.40), (80, 1.44), (90, 1.48), (100, 1.52),
- (110, 1.56), (120, 1.61), (130, 1.65), (140, 1.68), (150, 1.72), (160, 1.76),
- (170, 1.80), (180, 1.84), (190, 1.88), (200, 1.92), (210, 1.96), (220, 2.00),
- (230, 2.04), (240, 2.07), (250, 2.11), (260, 2.15), (270, 2.18), (280, 2.22),
- (290, 2.26), (300, 2.29), (310, 2.33), (320, 2.37), (330, 2.41), (340, 2.44),
- (350, 2.48), (360, 2.51), (370, 2.55), (380, 2.58), (390, 2.62), (400, 2.66),
- (500, 3.00), (600, 3.33), (700, 3.63), (800, 3.93), (900, 4.21),
- (1000, 4.48), (1100, 4.73)
- ]
- def load_config(config):
- # Register default sensors
- pheater = config.get_printer().lookup_object("heater")
- for sensor_type, params in [("AD595", AD595), ("PT100 INA826", PT100)]:
- func = (lambda config, params=params: Linear(config, params))
- pheater.add_sensor(sensor_type, func)
- def load_config_prefix(config):
- linear = CustomLinear(config)
- pheater = config.get_printer().lookup_object("heater")
- pheater.add_sensor(linear.name, linear.create)
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