Rahix
37b58a1529
To sanity-check the filtered result, also plot the raw value alongside it each time.
51 lines
1.1 KiB
Python
51 lines
1.1 KiB
Python
import math
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import time
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from cs1237 import CS1237
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from machine import Pin
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clock = Pin(2)
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data = Pin(4)
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ADC_RATE = 40
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cs1237 = CS1237(clock, data)
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cs1237.config(gain=1, rate=ADC_RATE)
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cs1237.get_config()
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THERMISTOR_BETA = 3950.0
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THERMISTOR_R25 = 10e3
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THERMISTOR_RINF = THERMISTOR_R25 * math.exp(-THERMISTOR_BETA / 298.15)
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# Filter constant in seconds
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FILTER_RC = 100
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FILTER_A = 1 / ADC_RATE / (FILTER_RC / 1 / ADC_RATE)
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temperature_filtered = -1
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# Ignore the first 5 seconds
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last_report = time.ticks_ms() + 5000
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while True:
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raw_value = cs1237.read()
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value = float(raw_value) / (2**24 - 1)
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if value > 0.9999:
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value = 0
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else:
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value = 10e3 * 1 / (1 / value - 1)
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temperature = THERMISTOR_BETA / math.log(value / THERMISTOR_RINF) - 273.15
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if temperature_filtered == -1:
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temperature_filtered = temperature
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temperature_filtered = (
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temperature_filtered * (1 - FILTER_A) + temperature * FILTER_A
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)
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now = time.ticks_ms()
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elapsed = now - last_report
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if elapsed >= 200 or elapsed < 0:
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print(f"{temperature:.6f},{temperature_filtered:.6f}")
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last_report = now
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