560 lines
21 KiB
Python
560 lines
21 KiB
Python
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# Author(s): Jonathan Hanson 2018
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#
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# This is more or less a straight read of the Bosch data sheet at:
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# https://www.bosch-sensortec.com/bst/products/all_products/bme280
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# and specifically:
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# https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-12.pdf
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#
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# Modeled on the reference library Bosch Sensortec C library at:
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# https://github.com/BoschSensortec/BME280_driver
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#
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# The development of this module was heavily guided by the prior work done
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# by Peter Dahlberg et al at:
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# https://github.com/catdog2/mpy_bme280_esp8266
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from micropython import const
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from ustruct import unpack, unpack_from
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from utime import sleep_ms
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# BME280 default address
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BME280_I2C_ADDR_PRIM = const(0x76)
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BME280_I2C_ADDR_SEC = const(0x77)
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# Sensor Power Mode Options
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BME280_SLEEP_MODE = const(0x00)
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BME280_FORCED_MODE = const(0x01)
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BME280_NORMAL_MODE = const(0x03)
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# Oversampling Options
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BME280_NO_OVERSAMPLING = const(0x00)
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BME280_OVERSAMPLING_1X = const(0x01)
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BME280_OVERSAMPLING_2X = const(0x02)
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BME280_OVERSAMPLING_4X = const(0x03)
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BME280_OVERSAMPLING_8X = const(0x04)
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BME280_OVERSAMPLING_16X = const(0x05)
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# Standby Duration Options
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BME280_STANDBY_TIME_500_US = const(0x00) # Note this is microseconds, so 0.5 ms
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BME280_STANDBY_TIME_62_5_MS = const(0x01)
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BME280_STANDBY_TIME_125_MS = const(0x02)
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BME280_STANDBY_TIME_250_MS = const(0x03)
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BME280_STANDBY_TIME_500_MS = const(0x04)
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BME280_STANDBY_TIME_1000_MS = const(0x05)
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BME280_STANDBY_TIME_10_MS = const(0x06)
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BME280_STANDBY_TIME_20_MS = const(0x07)
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# Filter Coefficient Options
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BME280_FILTER_COEFF_OFF = const(0x00)
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BME280_FILTER_COEFF_2 = const(0x01)
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BME280_FILTER_COEFF_4 = const(0x02)
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BME280_FILTER_COEFF_8 = const(0x03)
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BME280_FILTER_COEFF_16 = const(0x04)
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# BME280 Chip ID
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_BME280_CHIP_ID = const(0x60)
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# Register Addresses
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_BME280_CHIP_ID_ADDR = const(0xD0)
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_BME280_RESET_ADDR = const(0xE0)
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_BME280_TEMP_PRESS_CALIB_DATA_ADDR = const(0x88)
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_BME280_HUMIDITY_CALIB_DATA_ADDR = const(0xE1)
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_BME280_PWR_CTRL_ADDR = const(0xF4)
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_BME280_CTRL_HUM_ADDR = const(0xF2)
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_BME280_CTRL_MEAS_ADDR = const(0xF4)
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_BME280_CONFIG_ADDR = const(0xF5)
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_BME280_DATA_ADDR = const(0xF7)
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# Register range sizes
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_BME280_TEMP_PRESS_CALIB_DATA_LEN = const(26)
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_BME280_HUMIDITY_CALIB_DATA_LEN = const(7)
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_BME280_P_T_H_DATA_LEN = const(8)
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class BME280_I2C:
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def __init__(self, address: int = BME280_I2C_ADDR_PRIM, i2c=None):
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"""
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Ensure I2C communication with the sensor is working, reset the sensor,
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and load its calibration data into memory.
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"""
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self.address = address
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if i2c is None:
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raise ValueError('A configured I2C object is required.')
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self.i2c = i2c
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self._read_chip_id()
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self._soft_reset()
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self._load_calibration_data()
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def _read_chip_id(self):
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"""
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Read the chip ID from the sensor and verify it's correct.
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If the value isn't correct, wait 1ms and try again.
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If 5 tries don't work, raise an exception.
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"""
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for x in range(5):
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mem = self.i2c.readfrom_mem(self.address, _BME280_CHIP_ID_ADDR, 1)
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if mem[0] == _BME280_CHIP_ID:
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return
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sleep_ms(1)
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raise Exception("Couldn't read BME280 chip ID after 5 attempts.")
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def _soft_reset(self):
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"""
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Write the reset command to the sensor's reset address.
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Wait 2ms, per the reference library's example.
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"""
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self.i2c.writeto_mem(self.address, _BME280_RESET_ADDR, bytearray([0xB6]))
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sleep_ms(2)
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def _load_calibration_data(self):
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"""
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Load the read-only calibration values out of the sensor's memory, to be
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used later in calibrating the raw reads. These get stored in various
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self.cal_dig_* object properties.
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See https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L1192
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See https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L1216
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See https://github.com/catdog2/mpy_bme280_esp8266/blob/master/bme280.py#L73
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"""
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# Load the temperature and pressure calibration data
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# (note that the first value of the humidity data is stuffed in here)
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tp_cal_mem = self.i2c.readfrom_mem(self.address,
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_BME280_TEMP_PRESS_CALIB_DATA_ADDR,
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_BME280_TEMP_PRESS_CALIB_DATA_LEN)
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(self.cal_dig_T1, self.cal_dig_T2, self.cal_dig_T3,
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self.cal_dig_P1, self.cal_dig_P2, self.cal_dig_P3,
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self.cal_dig_P4, self.cal_dig_P5, self.cal_dig_P6,
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self.cal_dig_P7, self.cal_dig_P8, self.cal_dig_P9,
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_,
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self.cal_dig_H1) = unpack("<HhhHhhhhhhhhBB", tp_cal_mem)
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# Load the rest of the humidity calibration data
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hum_cal_mem = self.i2c.readfrom_mem(self.address,
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_BME280_HUMIDITY_CALIB_DATA_ADDR,
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_BME280_HUMIDITY_CALIB_DATA_LEN)
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self.cal_dig_H2, self.cal_dig_H3 = unpack("<hB", hum_cal_mem)
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e4_sign = unpack_from("<b", hum_cal_mem, 3)[0]
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self.cal_dig_H4 = (e4_sign << 4) | (hum_cal_mem[4] & 0b00001111)
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e6_sign = unpack_from("<b", hum_cal_mem, 5)[0]
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self.cal_dig_H5 = (e6_sign << 4) | (hum_cal_mem[4] >> 4)
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self.cal_dig_H6 = unpack_from("<b", hum_cal_mem, 6)[0]
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# Initialize the cal_t_fine carry-over value used during compensation
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self.cal_t_fine = 0
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def get_measurement_settings(self):
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"""
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Return a parsed set of the sensor's measurement settings as a dict
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These values include oversampling settings for each measurement,
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the IIR filter coefficient, and the standby duration for normal
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power mode.
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See the data sheet, section 3 and 5
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"""
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mem = self.i2c.readfrom_mem(self.address, _BME280_CTRL_HUM_ADDR, 4)
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ctrl_hum, _, ctrl_meas, config = unpack("<BBBB", mem)
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return {
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"osr_h": (ctrl_hum & 0b00000111),
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"osr_p": (ctrl_meas >> 2) & 0b00000111,
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"osr_t": (ctrl_meas >> 5) & 0b00000111,
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"filter": (config >> 2) & 0b00000111,
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"standby_time": (config >> 5) & 0b00000111,
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}
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def set_measurement_settings(self, settings: dict):
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"""
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Set the sensor's settings for each measurement's oversampling,
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the pressure IIR filter coefficient, and standby duration
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during normal power mode.
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The settings dict can have keys osr_h, osr_p, osr_t, filter, and
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standby_time. All values are optional, and omitting any will retain
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the pre-existing value.
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See the data sheet, section 3 and 5
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"""
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self._validate_settings(settings)
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self._ensure_sensor_is_asleep()
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self._write_measurement_settings(settings)
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def _validate_settings(self, settings: dict):
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oversampling_options = [
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BME280_NO_OVERSAMPLING, BME280_OVERSAMPLING_1X,
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BME280_OVERSAMPLING_2X, BME280_OVERSAMPLING_4X,
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BME280_OVERSAMPLING_8X, BME280_OVERSAMPLING_16X]
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filter_options = [
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BME280_FILTER_COEFF_OFF, BME280_FILTER_COEFF_2,
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BME280_FILTER_COEFF_4, BME280_FILTER_COEFF_8,
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BME280_FILTER_COEFF_16]
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standby_time_options = [
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BME280_STANDBY_TIME_500_US,
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BME280_STANDBY_TIME_62_5_MS, BME280_STANDBY_TIME_125_MS,
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BME280_STANDBY_TIME_250_MS, BME280_STANDBY_TIME_500_MS,
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BME280_STANDBY_TIME_1000_MS, BME280_STANDBY_TIME_10_MS,
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BME280_STANDBY_TIME_20_MS]
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if 'osr_h' in settings:
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if settings['osr_h'] not in oversampling_options:
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raise ValueError("osr_h must be one of the oversampling defines")
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if 'osr_p' in settings:
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if settings['osr_h'] not in oversampling_options:
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raise ValueError("osr_p must be one of the oversampling defines")
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if 'osr_t' in settings:
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if settings['osr_h'] not in oversampling_options:
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raise ValueError("osr_t must be one of the oversampling defines")
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if 'filter' in settings:
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if settings['filter'] not in filter_options:
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raise ValueError("filter filter coefficient defines")
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if 'standby_time' in settings:
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if settings['standby_time'] not in standby_time_options:
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raise ValueError("standby_time must be one of the standby time duration defines")
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def _write_measurement_settings(self, settings: dict):
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# Read in the existing configuration, to modify
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mem = self.i2c.readfrom_mem(self.address, _BME280_CTRL_HUM_ADDR, 4)
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ctrl_hum, _, ctrl_meas, config = unpack("<BBBB", mem)
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# Make any changes necessary to the ctrl_hum register
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if "osr_h" in settings:
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newval = (ctrl_hum & 0b11111000) | (settings['osr_h'] & 0b00000111)
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self.i2c.writeto_mem(self.address, _BME280_CTRL_HUM_ADDR, bytearray([newval]))
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# according to the data sheet, ctrl_hum needs a write to
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# ctrl_meas in order to take effect
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self.i2c.writeto_mem(self.address, _BME280_CTRL_MEAS_ADDR, bytearray([ctrl_meas]))
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# Make any changes necessary to the ctrl_meas register
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if "osr_p" in settings or "osr_t" in settings:
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newval = ctrl_meas
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if "osr_p" in settings:
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newval = (newval & 0b11100011) | ((settings['osr_p'] << 2) & 0b00011100)
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if "osr_t" in settings:
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newval = (newval & 0b00011111) | ((settings['osr_t'] << 5) & 0b11100000)
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self.i2c.writeto_mem(self.address, _BME280_CTRL_MEAS_ADDR, bytearray([newval]))
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# Make any changes necessary to the config register
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if "filter" in settings or "standby_time" in settings:
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newval = config
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if "filter" in settings:
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newval = (newval & 0b11100011) | ((settings['filter'] << 2) & 0b00011100)
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if "standby_time" in settings:
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newval = (newval & 0b00011111) | ((settings['standby_time'] << 5) & 0b11100000)
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self.i2c.writeto_mem(self.address, _BME280_CONFIG_ADDR, bytearray([newval]))
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def get_power_mode(self):
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"""
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Result will be one of BME280_SLEEP_MODE, BME280_FORCED_MODE, or
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BME280_NORMAL_MODE.
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See the data sheet, section 3.3
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"""
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mem = self.i2c.readfrom_mem(self.address, _BME280_PWR_CTRL_ADDR, 1)
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return (mem[0] & 0b00000011)
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def set_power_mode(self, new_power_mode: int):
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"""
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Configure the sensor's power mode (BME280_SLEEP_MODE,
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BME280_FORCED_MODE, or BME280_NORMAL_MODE)
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Note that setting to forced mode will immediately set the sensor back
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to sleep mode after taking a measurement.
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See the data sheet, section 3.3
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"""
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if new_power_mode not in [BME280_SLEEP_MODE, BME280_FORCED_MODE, BME280_NORMAL_MODE]:
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raise ValueError("New power mode must be sleep, forced, or normal constant")
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self._ensure_sensor_is_asleep()
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# Read the current register, mask out and set the new power mode,
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# and write the register back to the device.
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mem = self.i2c.readfrom_mem(self.address, _BME280_PWR_CTRL_ADDR, 1)
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newval = (mem[0] & 0b11111100) | (new_power_mode & 0b00000011)
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self.i2c.writeto_mem(self.address, _BME280_PWR_CTRL_ADDR, bytearray([newval]))
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def _ensure_sensor_is_asleep(self):
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"""
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If the sensor mode isn't already "sleep", then put it to sleep.
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This is done by reading out the configuration values we want to keep,
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and then doing a soft reset and writing those values back.
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"""
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if self.get_power_mode() != BME280_SLEEP_MODE:
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settings = self.get_measurement_settings()
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self._soft_reset()
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self._write_measurement_settings(settings)
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def get_measurement(self):
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"""
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Return a set of measurements in decimal value, compensated with the
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sensor's stored calibration data.
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"""
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uncompensated_data = self._read_uncompensated_data()
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# Be sure to call self._compensate_temperature() first, as it sets a
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# global "fine" calibration value for the other two compensation
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# functions
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return {
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"temperature": self._compensate_temperature(uncompensated_data['temperature']),
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"pressure": self._compensate_pressure(uncompensated_data['pressure']),
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"humidity": self._compensate_humidity(uncompensated_data['humidity']),
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}
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def _read_uncompensated_data(self):
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# Read the uncompensated temperature, pressure, and humidity data
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mem = self.i2c.readfrom_mem(self.address, _BME280_DATA_ADDR, _BME280_P_T_H_DATA_LEN)
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(press_msb, press_lsb, press_xlsb,
|
||
|
|
temp_msb, temp_lsb, temp_xlsb,
|
||
|
|
hum_msb, hum_lsb) = unpack("<BBBBBBBB", mem)
|
||
|
|
|
||
|
|
# Assemble the values from the memory fragments and return a dict.
|
||
|
|
#
|
||
|
|
# Note that we're calling temperature first, since it sets the
|
||
|
|
# cal_t_fine value used in humidity and pressure.
|
||
|
|
return {
|
||
|
|
"temperature": (temp_msb << 12) | (temp_lsb << 4) | (temp_xlsb >> 4),
|
||
|
|
"pressure": (press_msb << 12) | (press_lsb << 4) | (press_xlsb >> 4),
|
||
|
|
"humidity": (hum_msb << 8) | (hum_lsb),
|
||
|
|
}
|
||
|
|
|
||
|
|
##
|
||
|
|
# Float Implementations
|
||
|
|
##
|
||
|
|
|
||
|
|
# def _compensate_temperature(self, adc_T: int) -> float:
|
||
|
|
# """
|
||
|
|
# Output value of “25.0” equals 25.0 DegC.
|
||
|
|
#
|
||
|
|
# See the floating-point implementation in the reference library:
|
||
|
|
# https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L884
|
||
|
|
# """
|
||
|
|
# temperature_min = -40
|
||
|
|
# temperature_max = 85
|
||
|
|
#
|
||
|
|
# var1 = (adc_T / 16384.0) - (self.cal_dig_T1 / 1024.0)
|
||
|
|
# var1 = var1 * self.cal_dig_T2
|
||
|
|
#
|
||
|
|
# var2 = (adc_T / 131072.0) - (self.cal_dig_T1 / 8192.0)
|
||
|
|
# var2 = var2 * var2 * self.cal_dig_T3
|
||
|
|
#
|
||
|
|
# self.cal_t_fine = int(var1 + var2)
|
||
|
|
#
|
||
|
|
# temperature = (var1 + var2) / 5120.0
|
||
|
|
#
|
||
|
|
# if temperature < temperature_min:
|
||
|
|
# temperature = temperature_min
|
||
|
|
# elif temperature > temperature_max:
|
||
|
|
# temperature = temperature_max
|
||
|
|
#
|
||
|
|
# return temperature
|
||
|
|
|
||
|
|
# def _compensate_pressure(self, adc_P: int) -> float:
|
||
|
|
# """
|
||
|
|
# Output value of “96386.0” equals 96386 Pa = 963.86 hPa
|
||
|
|
#
|
||
|
|
# See the floating-point implementation in the reference library:
|
||
|
|
# https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L912
|
||
|
|
# """
|
||
|
|
# pressure_min = 30000.0
|
||
|
|
# pressure_max = 110000.0
|
||
|
|
#
|
||
|
|
# var1 = (self.cal_t_fine / 2.0) - 64000.0
|
||
|
|
#
|
||
|
|
# var2 = var1 * var1 * self.cal_dig_P6 / 32768.0
|
||
|
|
# var2 = var2 + (var1 * self.cal_dig_P5 * 2.0)
|
||
|
|
# var2 = (var2 / 4.0) + (self.cal_dig_P4 * 65536.0)
|
||
|
|
#
|
||
|
|
# var3 = self.cal_dig_P3 * var1 * var1 / 524288.0
|
||
|
|
#
|
||
|
|
# var1 = (var3 + self.cal_dig_P2 * var1) / 524288.0
|
||
|
|
# var1 = (1.0 + var1 / 32768.0) * self.cal_dig_P1
|
||
|
|
#
|
||
|
|
# # avoid exception caused by division by zero
|
||
|
|
# if var1:
|
||
|
|
# pressure = 1048576.0 - adc_P
|
||
|
|
# pressure = (pressure - (var2 / 4096.0)) * 6250.0 / var1
|
||
|
|
# var1 = self.cal_dig_P9 * pressure * pressure / 2147483648.0
|
||
|
|
# var2 = pressure * self.cal_dig_P8 / 32768.0
|
||
|
|
# pressure = pressure + (var1 + var2 + self.cal_dig_P7) / 16.0
|
||
|
|
#
|
||
|
|
# if pressure < pressure_min:
|
||
|
|
# pressure = pressure_min
|
||
|
|
# elif pressure > pressure_max:
|
||
|
|
# pressure = pressure_max
|
||
|
|
#
|
||
|
|
# else:
|
||
|
|
# # Invalid case
|
||
|
|
# pressure = pressure_min
|
||
|
|
#
|
||
|
|
# return pressure
|
||
|
|
|
||
|
|
# def _compensate_humidity(self, adc_H: int) -> float:
|
||
|
|
# """
|
||
|
|
# Output value between 0.0 and 100.0, where 100.0 is 100%RH
|
||
|
|
#
|
||
|
|
# See the floating-point implementation in the reference library:
|
||
|
|
# https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L952
|
||
|
|
# """
|
||
|
|
# humidity_min = 0.0
|
||
|
|
# humidity_max = 100.0
|
||
|
|
#
|
||
|
|
# var1 = self.cal_t_fine - 76800.0
|
||
|
|
#
|
||
|
|
# var2 = self.cal_dig_H4 * 64.0 + (self.cal_dig_H5 / 16384.0) * var1
|
||
|
|
#
|
||
|
|
# var3 = adc_H - var2
|
||
|
|
#
|
||
|
|
# var4 = self.cal_dig_H2 / 65536.0
|
||
|
|
#
|
||
|
|
# var5 = 1.0 + (self.cal_dig_H3 / 67108864.0) * var1
|
||
|
|
#
|
||
|
|
# var6 = 1.0 + (self.cal_dig_H6 / 67108864.0) * var1 * var5
|
||
|
|
# var6 = var3 * var4 * (var5 * var6)
|
||
|
|
#
|
||
|
|
# humidity = var6 * (1.0 - self.cal_dig_H1 * var6 / 524288.0)
|
||
|
|
#
|
||
|
|
# if humidity > humidity_max:
|
||
|
|
# humidity = humidity_max
|
||
|
|
# elif humidity < humidity_min:
|
||
|
|
# humidity = humidity_min
|
||
|
|
#
|
||
|
|
# return humidity
|
||
|
|
|
||
|
|
##
|
||
|
|
# 32-Bit Integer Implementations
|
||
|
|
##
|
||
|
|
|
||
|
|
def _compensate_temperature(self, adc_T: int) -> float:
|
||
|
|
"""
|
||
|
|
Output value of “25.0” equals 25.0 DegC.
|
||
|
|
|
||
|
|
See the integer implementation in the data sheet, section 4.2.3
|
||
|
|
And the reference library:
|
||
|
|
https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L987
|
||
|
|
"""
|
||
|
|
temperature_min = -4000
|
||
|
|
temperature_max = 8500
|
||
|
|
|
||
|
|
var1 = (((adc_T // 8) - (self.cal_dig_T1 * 2)) * self.cal_dig_T2) // 2048
|
||
|
|
|
||
|
|
var2 = (((((adc_T // 16) - self.cal_dig_T1) * ((adc_T // 16) - self.cal_dig_T1)) // 4096) * self.cal_dig_T3) // 16384
|
||
|
|
|
||
|
|
self.cal_t_fine = var1 + var2
|
||
|
|
|
||
|
|
temperature = (self.cal_t_fine * 5 + 128) // 256
|
||
|
|
|
||
|
|
if temperature < temperature_min:
|
||
|
|
temperature = temperature_min
|
||
|
|
elif temperature > temperature_max:
|
||
|
|
temperature = temperature_max
|
||
|
|
|
||
|
|
return temperature / 100
|
||
|
|
|
||
|
|
def _compensate_pressure(self, adc_P: int) -> float:
|
||
|
|
"""
|
||
|
|
Output value of “96386.0” equals 96386 Pa = 963.86 hPa
|
||
|
|
|
||
|
|
See the 32-bit integer implementation in the data sheet, section 4.2.3
|
||
|
|
And the reference library:
|
||
|
|
https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#L1059
|
||
|
|
|
||
|
|
Note that there's a 64-bit version of this function in the reference
|
||
|
|
library on line 1016 that we're leaving unimplemented.
|
||
|
|
"""
|
||
|
|
pressure_min = 30000
|
||
|
|
pressure_max = 110000
|
||
|
|
|
||
|
|
var1 = (self.cal_t_fine // 2) - 64000
|
||
|
|
|
||
|
|
var2 = (((var1 // 4) * (var1 // 4)) // 2048) * self.cal_dig_P6
|
||
|
|
var2 = var2 + ((var1 * self.cal_dig_P5) * 2)
|
||
|
|
var2 = (var2 // 4) + (self.cal_dig_P4 * 65536)
|
||
|
|
|
||
|
|
var3 = (self.cal_dig_P3 * (((var1 // 4) * (var1 // 4)) // 8192)) // 8
|
||
|
|
|
||
|
|
var4 = (self.cal_dig_P2 * var1) // 2
|
||
|
|
|
||
|
|
var1 = (var3 + var4) // 262144
|
||
|
|
var1 = ((32768 + var1) * self.cal_dig_P1) // 32768
|
||
|
|
|
||
|
|
# avoid exception caused by division by zero
|
||
|
|
if var1:
|
||
|
|
var5 = 1048576 - adc_P
|
||
|
|
|
||
|
|
pressure = (var5 - (var2 // 4096)) * 3125
|
||
|
|
|
||
|
|
if pressure < 0x80000000:
|
||
|
|
pressure = (pressure << 1) // var1
|
||
|
|
else:
|
||
|
|
pressure = (pressure // var1) * 2
|
||
|
|
|
||
|
|
var1 = (self.cal_dig_P9 * (((pressure // 8) * (pressure // 8)) // 8192)) // 4096
|
||
|
|
|
||
|
|
var2 = (((pressure // 4)) * self.cal_dig_P8) // 8192
|
||
|
|
|
||
|
|
pressure = pressure + ((var1 + var2 + self.cal_dig_P7) // 16)
|
||
|
|
|
||
|
|
if pressure < pressure_min:
|
||
|
|
pressure = pressure_min
|
||
|
|
elif pressure > pressure_max:
|
||
|
|
pressure = pressure_max
|
||
|
|
|
||
|
|
else:
|
||
|
|
# Invalid case
|
||
|
|
pressure = pressure_min
|
||
|
|
|
||
|
|
return pressure
|
||
|
|
|
||
|
|
def _compensate_humidity(self, adc_H: int) -> float:
|
||
|
|
"""
|
||
|
|
Output value between 0.0 and 100.0, where 100.0 is 100%RH
|
||
|
|
|
||
|
|
See the floating-point implementation in the reference library:
|
||
|
|
https://github.com/BoschSensortec/BME280_driver/blob/bme280_v3.3.4/bme280.c#1108
|
||
|
|
"""
|
||
|
|
|
||
|
|
humidity_max = 102400
|
||
|
|
|
||
|
|
var1 = self.cal_t_fine - 76800
|
||
|
|
|
||
|
|
var2 = adc_H * 16384
|
||
|
|
|
||
|
|
var3 = self.cal_dig_H4 * 1048576
|
||
|
|
|
||
|
|
var4 = self.cal_dig_H5 * var1
|
||
|
|
|
||
|
|
var5 = (((var2 - var3) - var4) + 16384) // 32768
|
||
|
|
|
||
|
|
var2 = (var1 * self.cal_dig_H6) // 1024
|
||
|
|
|
||
|
|
var3 = (var1 * self.cal_dig_H3) // 2048
|
||
|
|
|
||
|
|
var4 = ((var2 * (var3 + 32768)) // 1024) + 2097152
|
||
|
|
|
||
|
|
var2 = ((var4 * self.cal_dig_H2) + 8192) // 16384
|
||
|
|
|
||
|
|
var3 = var5 * var2
|
||
|
|
|
||
|
|
var4 = ((var3 // 32768) * (var3 // 32768)) // 128
|
||
|
|
|
||
|
|
var5 = var3 - ((var4 * self.cal_dig_H1) // 16)
|
||
|
|
if var5 < 0:
|
||
|
|
var5 = 0
|
||
|
|
if var5 > 419430400:
|
||
|
|
var5 = 419430400
|
||
|
|
|
||
|
|
humidity = var5 // 4096
|
||
|
|
|
||
|
|
if (humidity > humidity_max):
|
||
|
|
humidity = humidity_max
|
||
|
|
|
||
|
|
return humidity / 1024
|