425 lines
17 KiB
Python
425 lines
17 KiB
Python
"""BME680 Temperature, Pressure, Humidity & Gas Sensor."""
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from .constants import lookupTable1, lookupTable2
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from .constants import BME680Data
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from . import constants
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import math
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import time
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__version__ = '1.0.5'
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# Export constants to global namespace
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# so end-users can "from BME680 import NAME"
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for key in constants.__dict__:
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value = constants.__dict__[key]
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if key not in globals():
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globals()[key] = value
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class BME680(BME680Data):
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"""BOSCH BME680.
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Gas, pressure, temperature and humidity sensor.
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:param i2c_addr: One of I2C_ADDR_PRIMARY (0x76) or I2C_ADDR_SECONDARY (0x77)
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:param i2c_device: Optional smbus or compatible instance for facilitating i2c communications.
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"""
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def __init__(self, i2c_addr=constants.I2C_ADDR_PRIMARY, i2c_device=None):
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"""Initialise BME680 sensor instance and verify device presence.
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:param i2c_addr: i2c address of BME680
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:param i2c_device: Optional SMBus-compatible instance for i2c transport
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"""
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BME680Data.__init__(self)
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self.i2c_addr = i2c_addr
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self._i2c = i2c_device
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if self._i2c is None:
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import smbus
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self._i2c = smbus.SMBus(1)
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self.chip_id = self._get_regs(constants.CHIP_ID_ADDR, 1)
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if self.chip_id != constants.CHIP_ID:
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raise RuntimeError('BME680 Not Found. Invalid CHIP ID: 0x{0:02x}'.format(self.chip_id))
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self.soft_reset()
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self.set_power_mode(constants.SLEEP_MODE)
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self._get_calibration_data()
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self.set_humidity_oversample(constants.OS_2X)
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self.set_pressure_oversample(constants.OS_4X)
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self.set_temperature_oversample(constants.OS_8X)
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self.set_filter(constants.FILTER_SIZE_3)
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self.set_gas_status(constants.ENABLE_GAS_MEAS)
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self.set_temp_offset(0)
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self.get_sensor_data()
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def _get_calibration_data(self):
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"""Retrieve the sensor calibration data and store it in .calibration_data."""
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calibration = self._get_regs(constants.COEFF_ADDR1, constants.COEFF_ADDR1_LEN)
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calibration += self._get_regs(constants.COEFF_ADDR2, constants.COEFF_ADDR2_LEN)
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heat_range = self._get_regs(constants.ADDR_RES_HEAT_RANGE_ADDR, 1)
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heat_value = constants.twos_comp(self._get_regs(constants.ADDR_RES_HEAT_VAL_ADDR, 1), bits=8)
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sw_error = constants.twos_comp(self._get_regs(constants.ADDR_RANGE_SW_ERR_ADDR, 1), bits=8)
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self.calibration_data.set_from_array(calibration)
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self.calibration_data.set_other(heat_range, heat_value, sw_error)
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def soft_reset(self):
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"""Trigger a soft reset."""
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self._set_regs(constants.SOFT_RESET_ADDR, constants.SOFT_RESET_CMD)
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time.sleep(constants.RESET_PERIOD / 1000.0)
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def set_temp_offset(self, value):
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"""Set temperature offset in celsius.
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If set, the temperature t_fine will be increased by given value in celsius.
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:param value: Temperature offset in Celsius, eg. 4, -8, 1.25
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"""
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if value == 0:
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self.offset_temp_in_t_fine = 0
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else:
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self.offset_temp_in_t_fine = int(math.copysign((((int(abs(value) * 100)) << 8) - 128) / 5, value))
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def set_humidity_oversample(self, value):
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"""Set humidity oversampling.
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A higher oversampling value means more stable sensor readings,
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with less noise and jitter.
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However each step of oversampling adds about 2ms to the latency,
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causing a slower response time to fast transients.
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:param value: Oversampling value, one of: OS_NONE, OS_1X, OS_2X, OS_4X, OS_8X, OS_16X
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"""
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self.tph_settings.os_hum = value
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self._set_bits(constants.CONF_OS_H_ADDR, constants.OSH_MSK, constants.OSH_POS, value)
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def get_humidity_oversample(self):
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"""Get humidity oversampling."""
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return (self._get_regs(constants.CONF_OS_H_ADDR, 1) & constants.OSH_MSK) >> constants.OSH_POS
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def set_pressure_oversample(self, value):
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"""Set temperature oversampling.
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A higher oversampling value means more stable sensor readings,
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with less noise and jitter.
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However each step of oversampling adds about 2ms to the latency,
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causing a slower response time to fast transients.
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:param value: Oversampling value, one of: OS_NONE, OS_1X, OS_2X, OS_4X, OS_8X, OS_16X
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"""
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self.tph_settings.os_pres = value
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self._set_bits(constants.CONF_T_P_MODE_ADDR, constants.OSP_MSK, constants.OSP_POS, value)
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def get_pressure_oversample(self):
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"""Get pressure oversampling."""
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return (self._get_regs(constants.CONF_T_P_MODE_ADDR, 1) & constants.OSP_MSK) >> constants.OSP_POS
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def set_temperature_oversample(self, value):
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"""Set pressure oversampling.
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A higher oversampling value means more stable sensor readings,
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with less noise and jitter.
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However each step of oversampling adds about 2ms to the latency,
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causing a slower response time to fast transients.
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:param value: Oversampling value, one of: OS_NONE, OS_1X, OS_2X, OS_4X, OS_8X, OS_16X
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"""
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self.tph_settings.os_temp = value
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self._set_bits(constants.CONF_T_P_MODE_ADDR, constants.OST_MSK, constants.OST_POS, value)
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def get_temperature_oversample(self):
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"""Get temperature oversampling."""
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return (self._get_regs(constants.CONF_T_P_MODE_ADDR, 1) & constants.OST_MSK) >> constants.OST_POS
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def set_filter(self, value):
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"""Set IIR filter size.
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Optionally remove short term fluctuations from the temperature and pressure readings,
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increasing their resolution but reducing their bandwidth.
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Enabling the IIR filter does not slow down the time a reading takes, but will slow
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down the BME680s response to changes in temperature and pressure.
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When the IIR filter is enabled, the temperature and pressure resolution is effectively 20bit.
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When it is disabled, it is 16bit + oversampling-1 bits.
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"""
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self.tph_settings.filter = value
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self._set_bits(constants.CONF_ODR_FILT_ADDR, constants.FILTER_MSK, constants.FILTER_POS, value)
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def get_filter(self):
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"""Get filter size."""
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return (self._get_regs(constants.CONF_ODR_FILT_ADDR, 1) & constants.FILTER_MSK) >> constants.FILTER_POS
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def select_gas_heater_profile(self, value):
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"""Set current gas sensor conversion profile.
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Select one of the 10 configured heating durations/set points.
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:param value: Profile index from 0 to 9
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"""
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if value > constants.NBCONV_MAX or value < constants.NBCONV_MIN:
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raise ValueError("Profile '{}' should be between {} and {}".format(value, constants.NBCONV_MIN, constants.NBCONV_MAX))
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self.gas_settings.nb_conv = value
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self._set_bits(constants.CONF_ODR_RUN_GAS_NBC_ADDR, constants.NBCONV_MSK, constants.NBCONV_POS, value)
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def get_gas_heater_profile(self):
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"""Get gas sensor conversion profile: 0 to 9."""
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return self._get_regs(constants.CONF_ODR_RUN_GAS_NBC_ADDR, 1) & constants.NBCONV_MSK
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def set_gas_status(self, value):
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"""Enable/disable gas sensor."""
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self.gas_settings.run_gas = value
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self._set_bits(constants.CONF_ODR_RUN_GAS_NBC_ADDR, constants.RUN_GAS_MSK, constants.RUN_GAS_POS, value)
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def get_gas_status(self):
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"""Get the current gas status."""
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return (self._get_regs(constants.CONF_ODR_RUN_GAS_NBC_ADDR, 1) & constants.RUN_GAS_MSK) >> constants.RUN_GAS_POS
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def set_gas_heater_profile(self, temperature, duration, nb_profile=0):
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"""Set temperature and duration of gas sensor heater.
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:param temperature: Target temperature in degrees celsius, between 200 and 400
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:param durarion: Target duration in milliseconds, between 1 and 4032
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:param nb_profile: Target profile, between 0 and 9
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"""
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self.set_gas_heater_temperature(temperature, nb_profile=nb_profile)
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self.set_gas_heater_duration(duration, nb_profile=nb_profile)
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def set_gas_heater_temperature(self, value, nb_profile=0):
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"""Set gas sensor heater temperature.
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:param value: Target temperature in degrees celsius, between 200 and 400
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When setting an nb_profile other than 0,
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make sure to select it with select_gas_heater_profile.
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"""
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if nb_profile > constants.NBCONV_MAX or value < constants.NBCONV_MIN:
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raise ValueError('Profile "{}" should be between {} and {}'.format(nb_profile, constants.NBCONV_MIN, constants.NBCONV_MAX))
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self.gas_settings.heatr_temp = value
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temp = int(self._calc_heater_resistance(self.gas_settings.heatr_temp))
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self._set_regs(constants.RES_HEAT0_ADDR + nb_profile, temp)
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def set_gas_heater_duration(self, value, nb_profile=0):
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"""Set gas sensor heater duration.
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Heating durations between 1 ms and 4032 ms can be configured.
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Approximately 20-30 ms are necessary for the heater to reach the intended target temperature.
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:param value: Heating duration in milliseconds.
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When setting an nb_profile other than 0,
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make sure to select it with select_gas_heater_profile.
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"""
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if nb_profile > constants.NBCONV_MAX or value < constants.NBCONV_MIN:
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raise ValueError('Profile "{}" should be between {} and {}'.format(nb_profile, constants.NBCONV_MIN, constants.NBCONV_MAX))
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self.gas_settings.heatr_dur = value
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temp = self._calc_heater_duration(self.gas_settings.heatr_dur)
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self._set_regs(constants.GAS_WAIT0_ADDR + nb_profile, temp)
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def set_power_mode(self, value, blocking=True):
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"""Set power mode."""
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if value not in (constants.SLEEP_MODE, constants.FORCED_MODE):
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raise ValueError('Power mode should be one of SLEEP_MODE or FORCED_MODE')
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self.power_mode = value
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self._set_bits(constants.CONF_T_P_MODE_ADDR, constants.MODE_MSK, constants.MODE_POS, value)
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while blocking and self.get_power_mode() != self.power_mode:
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time.sleep(constants.POLL_PERIOD_MS / 1000.0)
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def get_power_mode(self):
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"""Get power mode."""
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self.power_mode = self._get_regs(constants.CONF_T_P_MODE_ADDR, 1)
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return self.power_mode
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def get_sensor_data(self):
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"""Get sensor data.
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Stores data in .data and returns True upon success.
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"""
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self.set_power_mode(constants.FORCED_MODE)
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for attempt in range(10):
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status = self._get_regs(constants.FIELD0_ADDR, 1)
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if (status & constants.NEW_DATA_MSK) == 0:
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time.sleep(constants.POLL_PERIOD_MS / 1000.0)
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continue
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regs = self._get_regs(constants.FIELD0_ADDR, constants.FIELD_LENGTH)
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self.data.status = regs[0] & constants.NEW_DATA_MSK
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# Contains the nb_profile used to obtain the current measurement
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self.data.gas_index = regs[0] & constants.GAS_INDEX_MSK
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self.data.meas_index = regs[1]
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adc_pres = (regs[2] << 12) | (regs[3] << 4) | (regs[4] >> 4)
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adc_temp = (regs[5] << 12) | (regs[6] << 4) | (regs[7] >> 4)
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adc_hum = (regs[8] << 8) | regs[9]
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adc_gas_res = (regs[13] << 2) | (regs[14] >> 6)
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gas_range = regs[14] & constants.GAS_RANGE_MSK
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self.data.status |= regs[14] & constants.GASM_VALID_MSK
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self.data.status |= regs[14] & constants.HEAT_STAB_MSK
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self.data.heat_stable = (self.data.status & constants.HEAT_STAB_MSK) > 0
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temperature = self._calc_temperature(adc_temp)
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self.data.temperature = temperature / 100.0
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self.ambient_temperature = temperature # Saved for heater calc
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self.data.pressure = self._calc_pressure(adc_pres) / 100.0
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self.data.humidity = self._calc_humidity(adc_hum) / 1000.0
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self.data.gas_resistance = self._calc_gas_resistance(adc_gas_res, gas_range)
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return True
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return False
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def _set_bits(self, register, mask, position, value):
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"""Mask out and set one or more bits in a register."""
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temp = self._get_regs(register, 1)
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temp &= ~mask
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temp |= value << position
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self._set_regs(register, temp)
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def _set_regs(self, register, value):
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"""Set one or more registers."""
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if isinstance(value, int):
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self._i2c.write_byte_data(self.i2c_addr, register, value)
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else:
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self._i2c.write_i2c_block_data(self.i2c_addr, register, value)
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def _get_regs(self, register, length):
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"""Get one or more registers."""
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if length == 1:
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return self._i2c.read_byte_data(self.i2c_addr, register)
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else:
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return self._i2c.read_i2c_block_data(self.i2c_addr, register, length)
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def _calc_temperature(self, temperature_adc):
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"""Convert the raw temperature to degrees C using calibration_data."""
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var1 = (temperature_adc >> 3) - (self.calibration_data.par_t1 << 1)
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var2 = (var1 * self.calibration_data.par_t2) >> 11
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var3 = ((var1 >> 1) * (var1 >> 1)) >> 12
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var3 = ((var3) * (self.calibration_data.par_t3 << 4)) >> 14
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# Save teperature data for pressure calculations
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self.calibration_data.t_fine = (var2 + var3) + self.offset_temp_in_t_fine
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calc_temp = (((self.calibration_data.t_fine * 5) + 128) >> 8)
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return calc_temp
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def _calc_pressure(self, pressure_adc):
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"""Convert the raw pressure using calibration data."""
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var1 = ((self.calibration_data.t_fine) >> 1) - 64000
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var2 = ((((var1 >> 2) * (var1 >> 2)) >> 11) *
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self.calibration_data.par_p6) >> 2
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var2 = var2 + ((var1 * self.calibration_data.par_p5) << 1)
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var2 = (var2 >> 2) + (self.calibration_data.par_p4 << 16)
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var1 = (((((var1 >> 2) * (var1 >> 2)) >> 13) *
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((self.calibration_data.par_p3 << 5)) >> 3) +
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((self.calibration_data.par_p2 * var1) >> 1))
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var1 = var1 >> 18
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var1 = ((32768 + var1) * self.calibration_data.par_p1) >> 15
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calc_pressure = 1048576 - pressure_adc
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calc_pressure = ((calc_pressure - (var2 >> 12)) * (3125))
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if calc_pressure >= (1 << 31):
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calc_pressure = ((calc_pressure // var1) << 1)
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else:
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calc_pressure = ((calc_pressure << 1) // var1)
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var1 = (self.calibration_data.par_p9 * (((calc_pressure >> 3) *
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(calc_pressure >> 3)) >> 13)) >> 12
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var2 = ((calc_pressure >> 2) *
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self.calibration_data.par_p8) >> 13
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var3 = ((calc_pressure >> 8) * (calc_pressure >> 8) *
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(calc_pressure >> 8) *
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self.calibration_data.par_p10) >> 17
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calc_pressure = (calc_pressure) + ((var1 + var2 + var3 +
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(self.calibration_data.par_p7 << 7)) >> 4)
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return calc_pressure
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def _calc_humidity(self, humidity_adc):
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"""Convert the raw humidity using calibration data."""
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temp_scaled = ((self.calibration_data.t_fine * 5) + 128) >> 8
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var1 = (humidity_adc - ((self.calibration_data.par_h1 * 16))) -\
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(((temp_scaled * self.calibration_data.par_h3) // (100)) >> 1)
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var2 = (self.calibration_data.par_h2 *
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(((temp_scaled * self.calibration_data.par_h4) // (100)) +
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(((temp_scaled * ((temp_scaled * self.calibration_data.par_h5) // (100))) >> 6) //
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(100)) + (1 * 16384))) >> 10
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var3 = var1 * var2
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var4 = self.calibration_data.par_h6 << 7
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var4 = ((var4) + ((temp_scaled * self.calibration_data.par_h7) // (100))) >> 4
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var5 = ((var3 >> 14) * (var3 >> 14)) >> 10
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var6 = (var4 * var5) >> 1
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calc_hum = (((var3 + var6) >> 10) * (1000)) >> 12
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return min(max(calc_hum, 0), 100000)
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def _calc_gas_resistance(self, gas_res_adc, gas_range):
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"""Convert the raw gas resistance using calibration data."""
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var1 = ((1340 + (5 * self.calibration_data.range_sw_err)) * (lookupTable1[gas_range])) >> 16
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var2 = (((gas_res_adc << 15) - (16777216)) + var1)
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var3 = ((lookupTable2[gas_range] * var1) >> 9)
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calc_gas_res = ((var3 + (var2 >> 1)) / var2)
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if calc_gas_res < 0:
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calc_gas_res = (1 << 32) + calc_gas_res
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return calc_gas_res
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def _calc_heater_resistance(self, temperature):
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"""Convert raw heater resistance using calibration data."""
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temperature = min(max(temperature, 200), 400)
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var1 = ((self.ambient_temperature * self.calibration_data.par_gh3) / 1000) * 256
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var2 = (self.calibration_data.par_gh1 + 784) * (((((self.calibration_data.par_gh2 + 154009) * temperature * 5) / 100) + 3276800) / 10)
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var3 = var1 + (var2 / 2)
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var4 = (var3 / (self.calibration_data.res_heat_range + 4))
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var5 = (131 * self.calibration_data.res_heat_val) + 65536
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heatr_res_x100 = (((var4 / var5) - 250) * 34)
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heatr_res = ((heatr_res_x100 + 50) / 100)
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return heatr_res
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def _calc_heater_duration(self, duration):
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"""Calculate correct value for heater duration setting from milliseconds."""
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if duration < 0xfc0:
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factor = 0
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while duration > 0x3f:
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duration /= 4
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factor += 1
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return int(duration + (factor * 64))
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return 0xff
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