mirror of
https://github.com/osmarks/random-stuff
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84 lines
3.1 KiB
Python
84 lines
3.1 KiB
Python
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import smbus
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import struct
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import time
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from prometheus_client import start_http_server, Gauge
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import sys
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location = sys.argv[1]
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bus = smbus.SMBus(1)
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ADDR = 0x76
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ID_REGISTER = 0xD0
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TARGET_ID = 0x58
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CTRL_MEAS_REGISTER = 0xF4
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PRESSURE_REGISTER_BASE = 0xF7
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TEMP_REGISTER_BASE = 0xFA
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CALIBRAITON_VALUES = {
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"dig_T1": {"address": (0x88, 0x89), "unpack": "<H"},
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"dig_T2": {"address": (0x8A, 0x8B), "unpack": "<h"},
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"dig_T3": {"address": (0x8C, 0x8D), "unpack": "<h"},
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"dig_P1": {"address": (0x8E, 0x8F), "unpack": "<H"},
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"dig_P2": {"address": (0x90, 0x91), "unpack": "<h"},
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"dig_P3": {"address": (0x92, 0x93), "unpack": "<h"},
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"dig_P4": {"address": (0x94, 0x95), "unpack": "<h"},
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"dig_P5": {"address": (0x96, 0x97), "unpack": "<h"},
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"dig_P6": {"address": (0x98, 0x99), "unpack": "<h"},
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"dig_P7": {"address": (0x9A, 0x9B), "unpack": "<h"},
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"dig_P8": {"address": (0x9C, 0x9D), "unpack": "<h"},
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"dig_P9": {"address": (0x9E, 0x9F), "unpack": "<h"}
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}
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def setup():
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assert bus.read_byte_data(ADDR, ID_REGISTER) == TARGET_ID
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bus.write_byte_data(ADDR, CTRL_MEAS_REGISTER, 0b101_101_11) # max oversampling mode (we don"t really care about power), power on
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calibration = {}
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for key, value in CALIBRAITON_VALUES.items():
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calibration[key] = struct.unpack(value["unpack"], bytes([bus.read_byte_data(ADDR, value["address"][0]), bus.read_byte_data(ADDR, value["address"][1])]))[0]
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return calibration
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def read_raw_adc(base):
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msb, lsb, xlsb = bus.read_i2c_block_data(ADDR, base, 3)
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return (msb << 16 | lsb << 8 | xlsb) >> 4
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def bmp280_compensate_T_double(adc_T, dig_T1, dig_T2, dig_T3, **kwargs):
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var1 = (adc_T / 16384.0 - dig_T1 / 1024.0) * dig_T2
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var2 = ((adc_T / 131072.0 - dig_T1 / 8192.0) *
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(adc_T / 131072.0 - dig_T1 / 8192.0)) * dig_T3
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t_fine = int(var1 + var2)
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T = (var1 + var2) / 5120.0
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return T, t_fine
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def bmp280_compensate_P_double(adc_P, t_fine, dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9, **kwargs):
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var1 = t_fine / 2.0 - 64000.0
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var2 = var1 * var1 * dig_P6 / 32768.0
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var2 = var2 + var1 * dig_P5 * 2.0
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var2 = (var2 / 4.0) + (dig_P4 * 65536.0)
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var1 = (dig_P3 * var1 * var1 / 524288.0 + dig_P2 * var1) / 524288.0
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var1 = (1.0 + var1 / 32768.0) * dig_P1
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if var1 == 0.0:
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return 0 # avoid exception caused by division by zero
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p = 1048576.0 - adc_P
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p = (p - (var2 / 4096.0)) * 6250.0 / var1
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var1 = dig_P9 * p * p / 2147483648.0
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var2 = p * dig_P8 / 32768.0
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p = p + (var1 + var2 + dig_P7) / 16.0
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return p
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calibration = setup()
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temperature = Gauge("bmp280_temperature", "Temperature in Celsius", ("location",))
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pressure = Gauge("bmp280_pressure", "Pressure in Pascals", ("location",))
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def read_temperature_pressure():
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adc_T = read_raw_adc(TEMP_REGISTER_BASE)
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adc_P = read_raw_adc(PRESSURE_REGISTER_BASE)
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T, t_fine = bmp280_compensate_T_double(adc_T, **calibration)
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P = bmp280_compensate_P_double(adc_P, t_fine, **calibration)
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temperature.labels(location=location).set(T)
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pressure.labels(location=location).set(P)
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start_http_server(9091)
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while True:
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read_temperature_pressure()
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time.sleep(1)
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