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""" |
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`adafruit_bme680` |
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================================================================================ |
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CircuitPython library for BME680 temperature, pressure and humidity sensor. |
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* Author(s): Limor Fried, William Garber, many others |
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Implementation Notes |
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-------------------- |
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**Hardware:** |
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* `Adafruit BME680 Temp, Humidity, Pressure and Gas Sensor <https://www.adafruit.com/product/3660>`_ |
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**Software and Dependencies:** |
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* Adafruit CircuitPython firmware for the supported boards: |
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https://github.com/adafruit/circuitpython/releases |
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* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice |
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""" |
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import math |
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import struct |
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import time |
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from micropython import const |
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def delay_microseconds(nusec): |
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"""HELP must be same as dev->delay_us""" |
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time.sleep(nusec / 1000000.0) |
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try: |
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import typing |
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from busio import I2C, SPI |
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from circuitpython_typing import ReadableBuffer |
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from digitalio import DigitalInOut |
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except ImportError: |
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pass |
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__version__ = "3.7.9" |
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__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BME680.git" |
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_BME68X_ENABLE_HEATER = const(0x00) |
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_BME68X_DISABLE_HEATER = const(0x01) |
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_BME68X_DISABLE_GAS_MEAS = const(0x00) |
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_BME68X_ENABLE_GAS_MEAS_L = const(0x01) |
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_BME68X_ENABLE_GAS_MEAS_H = const(0x02) |
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_BME68X_SLEEP_MODE = const(0) |
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_BME68X_FORCED_MODE = const(1) |
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_BME68X_VARIANT_GAS_LOW = const(0x00) |
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_BME68X_VARIANT_GAS_HIGH = const(0x01) |
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_BME68X_HCTRL_MSK = const(0x08) |
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_BME68X_HCTRL_POS = const(3) |
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_BME68X_NBCONV_MSK = const(0x0F) |
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_BME68X_RUN_GAS_MSK = const(0x30) |
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_BME68X_RUN_GAS_POS = const(4) |
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_BME68X_MODE_MSK = const(0x03) |
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_BME68X_PERIOD_POLL = const(10000) |
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_BME68X_REG_CTRL_GAS_0 = const(0x70) |
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_BME68X_REG_CTRL_GAS_1 = const(0x71) |
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_BME680_CHIPID = const(0x61) |
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_BME680_REG_CHIPID = const(0xD0) |
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_BME68X_REG_VARIANT = const(0xF0) |
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_BME680_BME680_COEFF_ADDR1 = const(0x89) |
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_BME680_BME680_COEFF_ADDR2 = const(0xE1) |
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_BME680_BME680_RES_HEAT_0 = const(0x5A) |
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_BME680_BME680_GAS_WAIT_0 = const(0x64) |
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_BME680_REG_SOFTRESET = const(0xE0) |
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_BME680_REG_CTRL_GAS = const(0x71) |
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_BME680_REG_CTRL_HUM = const(0x72) |
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_BME680_REG_STATUS = const(0x73) |
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_BME680_REG_CTRL_MEAS = const(0x74) |
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_BME680_REG_CONFIG = const(0x75) |
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_BME680_REG_MEAS_STATUS = const(0x1D) |
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_BME680_REG_PDATA = const(0x1F) |
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_BME680_REG_TDATA = const(0x22) |
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_BME680_REG_HDATA = const(0x25) |
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_BME680_SAMPLERATES = (0, 1, 2, 4, 8, 16) |
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_BME680_FILTERSIZES = (0, 1, 3, 7, 15, 31, 63, 127) |
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_BME680_RUNGAS = const(0x10) |
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_LOOKUP_TABLE_1 = ( |
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2147483647.0, |
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2147483647.0, |
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2147483647.0, |
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2147483647.0, |
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2147483647.0, |
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2126008810.0, |
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2147483647.0, |
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2130303777.0, |
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2147483647.0, |
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2147483647.0, |
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2143188679.0, |
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2136746228.0, |
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2147483647.0, |
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2126008810.0, |
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2147483647.0, |
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2147483647.0, |
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) |
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_LOOKUP_TABLE_2 = ( |
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4096000000.0, |
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2048000000.0, |
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1024000000.0, |
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512000000.0, |
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255744255.0, |
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127110228.0, |
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64000000.0, |
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32258064.0, |
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16016016.0, |
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8000000.0, |
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4000000.0, |
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2000000.0, |
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1000000.0, |
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500000.0, |
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250000.0, |
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125000.0, |
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) |
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def bme_set_bits(reg_data, bitname_msk, bitname_pos, data): |
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""" |
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Macro to set bits |
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data2 = data << bitname_pos |
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set masked bits from data2 in reg_data |
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""" |
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return (reg_data & ~bitname_msk) | ((data << bitname_pos) & bitname_msk) |
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def bme_set_bits_pos_0(reg_data, bitname_msk, data): |
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""" |
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Macro to set bits starting from position 0 |
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set masked bits from data in reg_data |
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""" |
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return (reg_data & ~bitname_msk) | (data & bitname_msk) |
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def _read24(arr: ReadableBuffer) -> float: |
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"""Parse an unsigned 24-bit value as a floating point and return it.""" |
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ret = 0.0 |
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for b in arr: |
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ret *= 256.0 |
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ret += float(b & 0xFF) |
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return ret |
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class Adafruit_BME680: |
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"""Driver from BME680 air quality sensor |
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:param int refresh_rate: Maximum number of readings per second. Faster property reads |
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will be from the previous reading.""" |
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def __init__(self, *, refresh_rate: int = 10) -> None: |
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"""Check the BME680 was found, read the coefficients and enable the sensor for continuous |
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reads.""" |
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self._write(_BME680_REG_SOFTRESET, [0xB6]) |
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time.sleep(0.005) |
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chip_id = self._read_byte(_BME680_REG_CHIPID) |
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if chip_id != _BME680_CHIPID: |
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raise RuntimeError("Failed to find BME680! Chip ID 0x%x" % chip_id) |
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self._chip_variant = self._read_byte(_BME68X_REG_VARIANT) |
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self._read_calibration() |
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self._write(_BME680_BME680_RES_HEAT_0, [0x73]) |
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self._write(_BME680_BME680_GAS_WAIT_0, [0x65]) |
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self.sea_level_pressure = 1013.25 |
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"""Pressure in hectoPascals at sea level. Used to calibrate :attr:`altitude`.""" |
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self._pressure_oversample = 0b011 |
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self._temp_oversample = 0b100 |
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self._humidity_oversample = 0b010 |
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self._filter = 0b010 |
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self._run_gas = 0xFF |
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self._adc_pres = None |
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self._adc_temp = None |
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self._adc_hum = None |
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self._adc_gas = None |
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self._gas_range = None |
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self._t_fine = None |
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self._last_reading = 0 |
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self._min_refresh_time = 1 / refresh_rate |
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self._amb_temp = 25 |
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self.set_gas_heater(320, 150) |
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@property |
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def pressure_oversample(self) -> int: |
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"""The oversampling for pressure sensor""" |
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return _BME680_SAMPLERATES[self._pressure_oversample] |
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@pressure_oversample.setter |
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def pressure_oversample(self, sample_rate: int) -> None: |
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if sample_rate in _BME680_SAMPLERATES: |
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self._pressure_oversample = _BME680_SAMPLERATES.index(sample_rate) |
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else: |
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raise RuntimeError("Invalid oversample") |
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@property |
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def humidity_oversample(self) -> int: |
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"""The oversampling for humidity sensor""" |
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return _BME680_SAMPLERATES[self._humidity_oversample] |
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@humidity_oversample.setter |
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def humidity_oversample(self, sample_rate: int) -> None: |
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if sample_rate in _BME680_SAMPLERATES: |
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self._humidity_oversample = _BME680_SAMPLERATES.index(sample_rate) |
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else: |
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raise RuntimeError("Invalid oversample") |
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@property |
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def temperature_oversample(self) -> int: |
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"""The oversampling for temperature sensor""" |
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return _BME680_SAMPLERATES[self._temp_oversample] |
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@temperature_oversample.setter |
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def temperature_oversample(self, sample_rate: int) -> None: |
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if sample_rate in _BME680_SAMPLERATES: |
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self._temp_oversample = _BME680_SAMPLERATES.index(sample_rate) |
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else: |
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raise RuntimeError("Invalid oversample") |
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@property |
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def filter_size(self) -> int: |
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"""The filter size for the built in IIR filter""" |
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return _BME680_FILTERSIZES[self._filter] |
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@filter_size.setter |
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def filter_size(self, size: int) -> None: |
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if size in _BME680_FILTERSIZES: |
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self._filter = _BME680_FILTERSIZES.index(size) |
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else: |
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raise RuntimeError("Invalid size") |
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@property |
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def temperature(self) -> float: |
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"""The compensated temperature in degrees Celsius.""" |
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self._perform_reading() |
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calc_temp = ((self._t_fine * 5) + 128) / 256 |
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return calc_temp / 100 |
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@property |
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def pressure(self) -> float: |
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"""The barometric pressure in hectoPascals""" |
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self._perform_reading() |
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var1 = (self._t_fine / 2) - 64000 |
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var2 = ((var1 / 4) * (var1 / 4)) / 2048 |
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var2 = (var2 * self._pressure_calibration[5]) / 4 |
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var2 = var2 + (var1 * self._pressure_calibration[4] * 2) |
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var2 = (var2 / 4) + (self._pressure_calibration[3] * 65536) |
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var1 = ((((var1 / 4) * (var1 / 4)) / 8192) * (self._pressure_calibration[2] * 32) / 8) + ( |
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(self._pressure_calibration[1] * var1) / 2 |
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) |
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var1 = var1 / 262144 |
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var1 = ((32768 + var1) * self._pressure_calibration[0]) / 32768 |
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calc_pres = 1048576 - self._adc_pres |
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calc_pres = (calc_pres - (var2 / 4096)) * 3125 |
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calc_pres = (calc_pres / var1) * 2 |
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var1 = (self._pressure_calibration[8] * (((calc_pres / 8) * (calc_pres / 8)) / 8192)) / 4096 |
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var2 = ((calc_pres / 4) * self._pressure_calibration[7]) / 8192 |
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var3 = (((calc_pres / 256) ** 3) * self._pressure_calibration[9]) / 131072 |
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calc_pres += (var1 + var2 + var3 + (self._pressure_calibration[6] * 128)) / 16 |
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return calc_pres / 100 |
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@property |
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def relative_humidity(self) -> float: |
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"""The relative humidity in RH %""" |
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return self.humidity |
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@property |
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def humidity(self) -> float: |
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"""The relative humidity in RH %""" |
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self._perform_reading() |
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temp_scaled = ((self._t_fine * 5) + 128) / 256 |
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var1 = (self._adc_hum - (self._humidity_calibration[0] * 16)) - ( |
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(temp_scaled * self._humidity_calibration[2]) / 200 |
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) |
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var2 = ( |
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self._humidity_calibration[1] |
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* ( |
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((temp_scaled * self._humidity_calibration[3]) / 100) |
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+ ( |
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((temp_scaled * ((temp_scaled * self._humidity_calibration[4]) / 100)) / 64) |
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/ 100 |
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) |
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+ 16384 |
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) |
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) / 1024 |
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var3 = var1 * var2 |
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var4 = self._humidity_calibration[5] * 128 |
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var4 = (var4 + ((temp_scaled * self._humidity_calibration[6]) / 100)) / 16 |
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var5 = ((var3 / 16384) * (var3 / 16384)) / 1024 |
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var6 = (var4 * var5) / 2 |
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calc_hum = (((var3 + var6) / 1024) * 1000) / 4096 |
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calc_hum /= 1000 |
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calc_hum = min(calc_hum, 100) |
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calc_hum = max(calc_hum, 0) |
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return calc_hum |
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@property |
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def altitude(self) -> float: |
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"""The altitude based on current :attr:`pressure` vs the sea level pressure |
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(:attr:`sea_level_pressure`) - which you must enter ahead of time)""" |
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pressure = self.pressure |
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return 44330 * (1.0 - math.pow(pressure / self.sea_level_pressure, 0.1903)) |
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@property |
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def gas(self) -> int: |
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"""The gas resistance in ohms""" |
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self._perform_reading() |
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if self._chip_variant == 0x01: |
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var1 = 262144 >> self._gas_range |
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var2 = self._adc_gas - 512 |
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var2 *= 3 |
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var2 = 4096 + var2 |
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calc_gas_res = (10000 * var1) / var2 |
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calc_gas_res = calc_gas_res * 100 |
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else: |
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var1 = ((1340 + (5 * self._sw_err)) * (_LOOKUP_TABLE_1[self._gas_range])) / 65536 |
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var2 = ((self._adc_gas * 32768) - 16777216) + var1 |
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var3 = (_LOOKUP_TABLE_2[self._gas_range] * var1) / 512 |
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calc_gas_res = (var3 + (var2 / 2)) / var2 |
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return int(calc_gas_res) |
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def _perform_reading(self) -> None: |
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"""Perform a single-shot reading from the sensor and fill internal data structure for |
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calculations""" |
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if time.monotonic() - self._last_reading < self._min_refresh_time: |
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return |
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self._write(_BME680_REG_CONFIG, [self._filter << 2]) |
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self._write( |
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_BME680_REG_CTRL_MEAS, |
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[(self._temp_oversample << 5) | (self._pressure_oversample << 2)], |
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) |
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self._write(_BME680_REG_CTRL_HUM, [self._humidity_oversample]) |
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if self._chip_variant == 0x01: |
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self._write(_BME680_REG_CTRL_GAS, [(self._run_gas & _BME680_RUNGAS) << 1]) |
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else: |
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self._write(_BME680_REG_CTRL_GAS, [(self._run_gas & _BME680_RUNGAS)]) |
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ctrl = self._read_byte(_BME680_REG_CTRL_MEAS) |
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ctrl = (ctrl & 0xFC) | 0x01 |
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self._write(_BME680_REG_CTRL_MEAS, [ctrl]) |
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new_data = False |
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while not new_data: |
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data = self._read(_BME680_REG_MEAS_STATUS, 17) |
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new_data = data[0] & 0x80 != 0 |
|
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time.sleep(0.005) |
|
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self._last_reading = time.monotonic() |
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self._adc_pres = _read24(data[2:5]) / 16 |
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self._adc_temp = _read24(data[5:8]) / 16 |
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self._adc_hum = struct.unpack(">H", bytes(data[8:10]))[0] |
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if self._chip_variant == 0x01: |
|
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self._adc_gas = int(struct.unpack(">H", bytes(data[15:17]))[0] / 64) |
|
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self._gas_range = data[16] & 0x0F |
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else: |
|
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self._adc_gas = int(struct.unpack(">H", bytes(data[13:15]))[0] / 64) |
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self._gas_range = data[14] & 0x0F |
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|
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var1 = (self._adc_temp / 8) - (self._temp_calibration[0] * 2) |
|
|
var2 = (var1 * self._temp_calibration[1]) / 2048 |
|
|
var3 = ((var1 / 2) * (var1 / 2)) / 4096 |
|
|
var3 = (var3 * self._temp_calibration[2] * 16) / 16384 |
|
|
self._t_fine = int(var2 + var3) |
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|
|
def _read_calibration(self) -> None: |
|
|
"""Read & save the calibration coefficients""" |
|
|
coeff = self._read(_BME680_BME680_COEFF_ADDR1, 25) |
|
|
coeff += self._read(_BME680_BME680_COEFF_ADDR2, 16) |
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|
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coeff = list(struct.unpack("<hbBHhbBhhbbHhhBBBHbbbBbHhbb", bytes(coeff[1:39]))) |
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|
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coeff = [float(i) for i in coeff] |
|
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self._temp_calibration = [coeff[x] for x in [23, 0, 1]] |
|
|
self._pressure_calibration = [coeff[x] for x in [3, 4, 5, 7, 8, 10, 9, 12, 13, 14]] |
|
|
self._humidity_calibration = [coeff[x] for x in [17, 16, 18, 19, 20, 21, 22]] |
|
|
self._gas_calibration = [coeff[x] for x in [25, 24, 26]] |
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|
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self._humidity_calibration[1] *= 16 |
|
|
self._humidity_calibration[1] += self._humidity_calibration[0] % 16 |
|
|
self._humidity_calibration[0] /= 16 |
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|
|
self._heat_range = (self._read_byte(0x02) & 0x30) / 16 |
|
|
self._heat_val = self._read_byte(0x00) |
|
|
self._sw_err = (self._read_byte(0x04) & 0xF0) / 16 |
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|
|
def _read_byte(self, register: int) -> int: |
|
|
"""Read a byte register value and return it""" |
|
|
return self._read(register, 1)[0] |
|
|
|
|
|
def _read(self, register: int, length: int) -> bytearray: |
|
|
raise NotImplementedError() |
|
|
|
|
|
def _write(self, register: int, values: bytearray) -> None: |
|
|
raise NotImplementedError() |
|
|
|
|
|
def set_gas_heater(self, heater_temp: int, heater_time: int) -> bool: |
|
|
""" |
|
|
Enable and configure gas reading + heater (None disables) |
|
|
:param heater_temp: Desired temperature in degrees Centigrade |
|
|
:param heater_time: Time to keep heater on in milliseconds |
|
|
:return: True on success, False on failure |
|
|
""" |
|
|
try: |
|
|
if (heater_temp is None) or (heater_time is None): |
|
|
self._set_heatr_conf(heater_temp or 0, heater_time or 0, enable=False) |
|
|
else: |
|
|
self._set_heatr_conf(heater_temp, heater_time) |
|
|
except OSError: |
|
|
return False |
|
|
return True |
|
|
|
|
|
def _set_heatr_conf(self, heater_temp: int, heater_time: int, enable: bool = True) -> None: |
|
|
|
|
|
op_mode: int = _BME68X_FORCED_MODE |
|
|
nb_conv: int = 0 |
|
|
hctrl: int = _BME68X_ENABLE_HEATER |
|
|
run_gas: int = 0 |
|
|
ctrl_gas_data_0: int = 0 |
|
|
ctrl_gas_data_1: int = 0 |
|
|
|
|
|
self._set_op_mode(_BME68X_SLEEP_MODE) |
|
|
self._set_conf(heater_temp, heater_time, op_mode) |
|
|
ctrl_gas_data_0 = self._read_byte(_BME68X_REG_CTRL_GAS_0) |
|
|
ctrl_gas_data_1 = self._read_byte(_BME68X_REG_CTRL_GAS_1) |
|
|
if enable: |
|
|
hctrl = _BME68X_ENABLE_HEATER |
|
|
if self._chip_variant == _BME68X_VARIANT_GAS_HIGH: |
|
|
run_gas = _BME68X_ENABLE_GAS_MEAS_H |
|
|
else: |
|
|
run_gas = _BME68X_ENABLE_GAS_MEAS_L |
|
|
else: |
|
|
hctrl = _BME68X_DISABLE_HEATER |
|
|
run_gas = _BME68X_DISABLE_GAS_MEAS |
|
|
self._run_gas = ~(run_gas - 1) |
|
|
|
|
|
ctrl_gas_data_0 = bme_set_bits(ctrl_gas_data_0, _BME68X_HCTRL_MSK, _BME68X_HCTRL_POS, hctrl) |
|
|
ctrl_gas_data_1 = bme_set_bits_pos_0(ctrl_gas_data_1, _BME68X_NBCONV_MSK, nb_conv) |
|
|
ctrl_gas_data_1 = bme_set_bits( |
|
|
ctrl_gas_data_1, _BME68X_RUN_GAS_MSK, _BME68X_RUN_GAS_POS, run_gas |
|
|
) |
|
|
self._write(_BME68X_REG_CTRL_GAS_0, [ctrl_gas_data_0]) |
|
|
self._write(_BME68X_REG_CTRL_GAS_1, [ctrl_gas_data_1]) |
|
|
|
|
|
def _set_op_mode(self, op_mode: int) -> None: |
|
|
""" |
|
|
* @brief This API is used to set the operation mode of the sensor |
|
|
""" |
|
|
tmp_pow_mode: int = 0 |
|
|
pow_mode: int = _BME68X_FORCED_MODE |
|
|
|
|
|
|
|
|
|
|
|
while pow_mode != _BME68X_SLEEP_MODE: |
|
|
tmp_pow_mode = self._read_byte(_BME680_REG_CTRL_MEAS) |
|
|
|
|
|
pow_mode = tmp_pow_mode & _BME68X_MODE_MSK |
|
|
if pow_mode != _BME68X_SLEEP_MODE: |
|
|
tmp_pow_mode &= ~_BME68X_MODE_MSK |
|
|
self._write(_BME680_REG_CTRL_MEAS, [tmp_pow_mode]) |
|
|
|
|
|
delay_microseconds(_BME68X_PERIOD_POLL) |
|
|
|
|
|
if op_mode != _BME68X_SLEEP_MODE: |
|
|
tmp_pow_mode = (tmp_pow_mode & ~_BME68X_MODE_MSK) | (op_mode & _BME68X_MODE_MSK) |
|
|
self._write(_BME680_REG_CTRL_MEAS, [tmp_pow_mode]) |
|
|
|
|
|
def _set_conf(self, heater_temp: int, heater_time: int, op_mode: int) -> None: |
|
|
""" |
|
|
This internal API is used to set heater configurations |
|
|
""" |
|
|
|
|
|
if op_mode != _BME68X_FORCED_MODE: |
|
|
raise OSError("GasHeaterException: _set_conf not forced mode") |
|
|
rh_reg_data: int = self._calc_res_heat(heater_temp) |
|
|
gw_reg_data: int = self._calc_gas_wait(heater_time) |
|
|
self._write(_BME680_BME680_RES_HEAT_0, [rh_reg_data]) |
|
|
self._write(_BME680_BME680_GAS_WAIT_0, [gw_reg_data]) |
|
|
|
|
|
def _calc_res_heat(self, temp: int) -> int: |
|
|
""" |
|
|
This internal API is used to calculate the heater resistance value using float |
|
|
""" |
|
|
gh1: int = self._gas_calibration[0] |
|
|
gh2: int = self._gas_calibration[1] |
|
|
gh3: int = self._gas_calibration[2] |
|
|
htr: int = self._heat_range |
|
|
htv: int = self._heat_val |
|
|
amb: int = self._amb_temp |
|
|
|
|
|
temp = min(temp, 400) |
|
|
|
|
|
var1: int = ((int(amb) * gh3) / 1000) * 256 |
|
|
var2: int = (gh1 + 784) * (((((gh2 + 154009) * temp * 5) / 100) + 3276800) / 10) |
|
|
var3: int = var1 + (var2 / 2) |
|
|
var4: int = var3 / (htr + 4) |
|
|
var5: int = (131 * htv) + 65536 |
|
|
heatr_res_x100: int = int(((var4 / var5) - 250) * 34) |
|
|
heatr_res: int = int((heatr_res_x100 + 50) / 100) |
|
|
|
|
|
return heatr_res |
|
|
|
|
|
def _calc_res_heat(self, temp: int) -> int: |
|
|
""" |
|
|
This internal API is used to calculate the heater resistance value |
|
|
""" |
|
|
gh1: float = float(self._gas_calibration[0]) |
|
|
gh2: float = float(self._gas_calibration[1]) |
|
|
gh3: float = float(self._gas_calibration[2]) |
|
|
htr: float = float(self._heat_range) |
|
|
htv: float = float(self._heat_val) |
|
|
amb: float = float(self._amb_temp) |
|
|
|
|
|
temp = min(temp, 400) |
|
|
|
|
|
var1: float = (gh1 / (16.0)) + 49.0 |
|
|
var2: float = ((gh2 / (32768.0)) * (0.0005)) + 0.00235 |
|
|
var3: float = gh3 / (1024.0) |
|
|
var4: float = var1 * (1.0 + (var2 * float(temp))) |
|
|
var5: float = var4 + (var3 * amb) |
|
|
res_heat: int = int(3.4 * ((var5 * (4 / (4 + htr)) * (1 / (1 + (htv * 0.002)))) - 25)) |
|
|
return res_heat |
|
|
|
|
|
def _calc_gas_wait(self, dur: int) -> int: |
|
|
""" |
|
|
This internal API is used to calculate the gas wait |
|
|
""" |
|
|
factor: int = 0 |
|
|
durval: int = 0xFF |
|
|
|
|
|
if dur >= 0xFC0: |
|
|
return durval |
|
|
while dur > 0x3F: |
|
|
dur = dur / 4 |
|
|
factor += 1 |
|
|
durval = int(dur + (factor * 64)) |
|
|
return durval |
|
|
|
|
|
|
|
|
class Adafruit_BME680_I2C(Adafruit_BME680): |
|
|
"""Driver for I2C connected BME680. |
|
|
|
|
|
:param ~busio.I2C i2c: The I2C bus the BME680 is connected to. |
|
|
:param int address: I2C device address. Defaults to :const:`0x77` |
|
|
:param bool debug: Print debug statements when `True`. Defaults to `False` |
|
|
:param int refresh_rate: Maximum number of readings per second. Faster property reads |
|
|
will be from the previous reading. |
|
|
|
|
|
**Quickstart: Importing and using the BME680** |
|
|
|
|
|
Here is an example of using the :class:`BMP680_I2C` class. |
|
|
First you will need to import the libraries to use the sensor |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
import board |
|
|
import adafruit_bme680 |
|
|
|
|
|
Once this is done you can define your ``board.I2C`` object and define your sensor object |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
i2c = board.I2C() # uses board.SCL and board.SDA |
|
|
bme680 = adafruit_bme680.Adafruit_BME680_I2C(i2c) |
|
|
|
|
|
You need to setup the pressure at sea level |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
bme680.sea_level_pressure = 1013.25 |
|
|
|
|
|
Now you have access to the :attr:`temperature`, :attr:`gas`, :attr:`relative_humidity`, |
|
|
:attr:`pressure` and :attr:`altitude` attributes |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
temperature = bme680.temperature |
|
|
gas = bme680.gas |
|
|
relative_humidity = bme680.relative_humidity |
|
|
pressure = bme680.pressure |
|
|
altitude = bme680.altitude |
|
|
|
|
|
""" |
|
|
|
|
|
def __init__( |
|
|
self, |
|
|
i2c: I2C, |
|
|
address: int = 0x77, |
|
|
debug: bool = False, |
|
|
*, |
|
|
refresh_rate: int = 10, |
|
|
) -> None: |
|
|
"""Initialize the I2C device at the 'address' given""" |
|
|
from adafruit_bus_device import ( |
|
|
i2c_device, |
|
|
) |
|
|
|
|
|
self._i2c = i2c_device.I2CDevice(i2c, address) |
|
|
self._debug = debug |
|
|
super().__init__(refresh_rate=refresh_rate) |
|
|
|
|
|
def _read(self, register: int, length: int) -> bytearray: |
|
|
"""Returns an array of 'length' bytes from the 'register'""" |
|
|
with self._i2c as i2c: |
|
|
i2c.write(bytes([register & 0xFF])) |
|
|
result = bytearray(length) |
|
|
i2c.readinto(result) |
|
|
if self._debug: |
|
|
print(f"\t${register:02X} => {[hex(i) for i in result]}") |
|
|
return result |
|
|
|
|
|
def _write(self, register: int, values: ReadableBuffer) -> None: |
|
|
"""Writes an array of 'length' bytes to the 'register'""" |
|
|
with self._i2c as i2c: |
|
|
buffer = bytearray(2 * len(values)) |
|
|
for i, value in enumerate(values): |
|
|
buffer[2 * i] = register + i |
|
|
buffer[2 * i + 1] = value |
|
|
i2c.write(buffer) |
|
|
if self._debug: |
|
|
print(f"\t${values[0]:02X} <= {[hex(i) for i in values[1:]]}") |
|
|
|
|
|
|
|
|
class Adafruit_BME680_SPI(Adafruit_BME680): |
|
|
"""Driver for SPI connected BME680. |
|
|
|
|
|
:param ~busio.SPI spi: SPI device |
|
|
:param ~digitalio.DigitalInOut cs: Chip Select |
|
|
:param bool debug: Print debug statements when `True`. Defaults to `False` |
|
|
:param int baudrate: Clock rate, default is :const:`100000` |
|
|
:param int refresh_rate: Maximum number of readings per second. Faster property reads |
|
|
will be from the previous reading. |
|
|
|
|
|
|
|
|
**Quickstart: Importing and using the BME680** |
|
|
|
|
|
Here is an example of using the :class:`BMP680_SPI` class. |
|
|
First you will need to import the libraries to use the sensor |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
import board |
|
|
from digitalio import DigitalInOut, Direction |
|
|
import adafruit_bme680 |
|
|
|
|
|
Once this is done you can define your ``board.SPI`` object and define your sensor object |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
cs = digitalio.DigitalInOut(board.D10) |
|
|
spi = board.SPI() |
|
|
bme680 = adafruit_bme680.Adafruit_BME680_SPI(spi, cs) |
|
|
|
|
|
You need to setup the pressure at sea level |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
bme680.sea_level_pressure = 1013.25 |
|
|
|
|
|
Now you have access to the :attr:`temperature`, :attr:`gas`, :attr:`relative_humidity`, |
|
|
:attr:`pressure` and :attr:`altitude` attributes |
|
|
|
|
|
.. code-block:: python |
|
|
|
|
|
temperature = bme680.temperature |
|
|
gas = bme680.gas |
|
|
relative_humidity = bme680.relative_humidity |
|
|
pressure = bme680.pressure |
|
|
altitude = bme680.altitude |
|
|
|
|
|
""" |
|
|
|
|
|
def __init__( |
|
|
self, |
|
|
spi: SPI, |
|
|
cs: DigitalInOut, |
|
|
baudrate: int = 100000, |
|
|
debug: bool = False, |
|
|
*, |
|
|
refresh_rate: int = 10, |
|
|
) -> None: |
|
|
from adafruit_bus_device import ( |
|
|
spi_device, |
|
|
) |
|
|
|
|
|
self._spi = spi_device.SPIDevice(spi, cs, baudrate=baudrate) |
|
|
self._debug = debug |
|
|
super().__init__(refresh_rate=refresh_rate) |
|
|
|
|
|
def _read(self, register: int, length: int) -> bytearray: |
|
|
if register != _BME680_REG_STATUS: |
|
|
|
|
|
|
|
|
self._set_spi_mem_page(register) |
|
|
|
|
|
register = (register | 0x80) & 0xFF |
|
|
with self._spi as spi: |
|
|
spi.write(bytearray([register])) |
|
|
result = bytearray(length) |
|
|
spi.readinto(result) |
|
|
if self._debug: |
|
|
print(f"\t${register:02X} => {[hex(i) for i in result]}") |
|
|
return result |
|
|
|
|
|
def _write(self, register: int, values: ReadableBuffer) -> None: |
|
|
if register != _BME680_REG_STATUS: |
|
|
|
|
|
|
|
|
self._set_spi_mem_page(register) |
|
|
register &= 0x7F |
|
|
with self._spi as spi: |
|
|
buffer = bytearray(2 * len(values)) |
|
|
for i, value in enumerate(values): |
|
|
buffer[2 * i] = register + i |
|
|
buffer[2 * i + 1] = value & 0xFF |
|
|
spi.write(buffer) |
|
|
if self._debug: |
|
|
print(f"\t${values[0]:02X} <= {[hex(i) for i in values[1:]]}") |
|
|
|
|
|
def _set_spi_mem_page(self, register: int) -> None: |
|
|
spi_mem_page = 0x00 |
|
|
if register < 0x80: |
|
|
spi_mem_page = 0x10 |
|
|
self._write(_BME680_REG_STATUS, [spi_mem_page]) |
|
|
|