# SPDX-FileCopyrightText: 2017 ladyada for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# We have a lot of attributes for this complex sensor.
# pylint: disable=too-many-instance-attributes
"""
`adafruit_bme680`
================================================================================
CircuitPython library for BME680 temperature, pressure and humidity sensor.
* Author(s): Limor Fried
Implementation Notes
--------------------
**Hardware:**
* `Adafruit BME680 Temp, Humidity, Pressure and Gas Sensor <https://www.adafruit.com/product/3660>`_
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://github.com/adafruit/circuitpython/releases
* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
"""
import time
import math
from micropython import const
try:
import struct
except ImportError:
import ustruct as struct
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BME680.git"
# I2C ADDRESS/BITS/SETTINGS
# -----------------------------------------------------------------------
_BME680_CHIPID = const(0x61)
_BME680_REG_CHIPID = const(0xD0)
_BME680_BME680_COEFF_ADDR1 = const(0x89)
_BME680_BME680_COEFF_ADDR2 = const(0xE1)
_BME680_BME680_RES_HEAT_0 = const(0x5A)
_BME680_BME680_GAS_WAIT_0 = const(0x64)
_BME680_REG_SOFTRESET = const(0xE0)
_BME680_REG_CTRL_GAS = const(0x71)
_BME680_REG_CTRL_HUM = const(0x72)
_BME680_REG_STATUS = const(0x73)
_BME680_REG_CTRL_MEAS = const(0x74)
_BME680_REG_CONFIG = const(0x75)
_BME680_REG_MEAS_STATUS = const(0x1D)
_BME680_REG_PDATA = const(0x1F)
_BME680_REG_TDATA = const(0x22)
_BME680_REG_HDATA = const(0x25)
_BME680_SAMPLERATES = (0, 1, 2, 4, 8, 16)
_BME680_FILTERSIZES = (0, 1, 3, 7, 15, 31, 63, 127)
_BME680_RUNGAS = const(0x10)
_LOOKUP_TABLE_1 = (
2147483647.0,
2147483647.0,
2147483647.0,
2147483647.0,
2147483647.0,
2126008810.0,
2147483647.0,
2130303777.0,
2147483647.0,
2147483647.0,
2143188679.0,
2136746228.0,
2147483647.0,
2126008810.0,
2147483647.0,
2147483647.0,
)
_LOOKUP_TABLE_2 = (
4096000000.0,
2048000000.0,
1024000000.0,
512000000.0,
255744255.0,
127110228.0,
64000000.0,
32258064.0,
16016016.0,
8000000.0,
4000000.0,
2000000.0,
1000000.0,
500000.0,
250000.0,
125000.0,
)
def _read24(arr):
"""Parse an unsigned 24-bit value as a floating point and return it."""
ret = 0.0
# print([hex(i) for i in arr])
for b in arr:
ret *= 256.0
ret += float(b & 0xFF)
return ret
[docs]class Adafruit_BME680:
"""Driver from BME680 air quality sensor
:param int refresh_rate: Maximum number of readings per second. Faster property reads
will be from the previous reading."""
def __init__(self, *, refresh_rate=10):
"""Check the BME680 was found, read the coefficients and enable the sensor for continuous
reads."""
self._write(_BME680_REG_SOFTRESET, [0xB6])
time.sleep(0.005)
# Check device ID.
chip_id = self._read_byte(_BME680_REG_CHIPID)
if chip_id != _BME680_CHIPID:
raise RuntimeError("Failed to find BME680! Chip ID 0x%x" % chip_id)
self._read_calibration()
# set up heater
self._write(_BME680_BME680_RES_HEAT_0, [0x73])
self._write(_BME680_BME680_GAS_WAIT_0, [0x65])
self.sea_level_pressure = 1013.25
"""Pressure in hectoPascals at sea level. Used to calibrate ``altitude``."""
# Default oversampling and filter register values.
self._pressure_oversample = 0b011
self._temp_oversample = 0b100
self._humidity_oversample = 0b010
self._filter = 0b010
self._adc_pres = None
self._adc_temp = None
self._adc_hum = None
self._adc_gas = None
self._gas_range = None
self._t_fine = None
self._last_reading = 0
self._min_refresh_time = 1 / refresh_rate
@property
def pressure_oversample(self):
"""The oversampling for pressure sensor"""
return _BME680_SAMPLERATES[self._pressure_oversample]
@pressure_oversample.setter
def pressure_oversample(self, sample_rate):
if sample_rate in _BME680_SAMPLERATES:
self._pressure_oversample = _BME680_SAMPLERATES.index(sample_rate)
else:
raise RuntimeError("Invalid oversample")
@property
def humidity_oversample(self):
"""The oversampling for humidity sensor"""
return _BME680_SAMPLERATES[self._humidity_oversample]
@humidity_oversample.setter
def humidity_oversample(self, sample_rate):
if sample_rate in _BME680_SAMPLERATES:
self._humidity_oversample = _BME680_SAMPLERATES.index(sample_rate)
else:
raise RuntimeError("Invalid oversample")
@property
def temperature_oversample(self):
"""The oversampling for temperature sensor"""
return _BME680_SAMPLERATES[self._temp_oversample]
@temperature_oversample.setter
def temperature_oversample(self, sample_rate):
if sample_rate in _BME680_SAMPLERATES:
self._temp_oversample = _BME680_SAMPLERATES.index(sample_rate)
else:
raise RuntimeError("Invalid oversample")
@property
def filter_size(self):
"""The filter size for the built in IIR filter"""
return _BME680_FILTERSIZES[self._filter]
@filter_size.setter
def filter_size(self, size):
if size in _BME680_FILTERSIZES:
self._filter = _BME680_FILTERSIZES.index(size)
else:
raise RuntimeError("Invalid size")
@property
def temperature(self):
"""The compensated temperature in degrees celsius."""
self._perform_reading()
calc_temp = ((self._t_fine * 5) + 128) / 256
return calc_temp / 100
@property
def pressure(self):
"""The barometric pressure in hectoPascals"""
self._perform_reading()
var1 = (self._t_fine / 2) - 64000
var2 = ((var1 / 4) * (var1 / 4)) / 2048
var2 = (var2 * self._pressure_calibration[5]) / 4
var2 = var2 + (var1 * self._pressure_calibration[4] * 2)
var2 = (var2 / 4) + (self._pressure_calibration[3] * 65536)
var1 = (
(((var1 / 4) * (var1 / 4)) / 8192)
* (self._pressure_calibration[2] * 32)
/ 8
) + ((self._pressure_calibration[1] * var1) / 2)
var1 = var1 / 262144
var1 = ((32768 + var1) * self._pressure_calibration[0]) / 32768
calc_pres = 1048576 - self._adc_pres
calc_pres = (calc_pres - (var2 / 4096)) * 3125
calc_pres = (calc_pres / var1) * 2
var1 = (
self._pressure_calibration[8] * (((calc_pres / 8) * (calc_pres / 8)) / 8192)
) / 4096
var2 = ((calc_pres / 4) * self._pressure_calibration[7]) / 8192
var3 = (((calc_pres / 256) ** 3) * self._pressure_calibration[9]) / 131072
calc_pres += (var1 + var2 + var3 + (self._pressure_calibration[6] * 128)) / 16
return calc_pres / 100
@property
def relative_humidity(self):
"""The relative humidity in RH %"""
return self.humidity
@property
def humidity(self):
"""The relative humidity in RH %"""
self._perform_reading()
temp_scaled = ((self._t_fine * 5) + 128) / 256
var1 = (self._adc_hum - (self._humidity_calibration[0] * 16)) - (
(temp_scaled * self._humidity_calibration[2]) / 200
)
var2 = (
self._humidity_calibration[1]
* (
((temp_scaled * self._humidity_calibration[3]) / 100)
+ (
(
(
temp_scaled
* ((temp_scaled * self._humidity_calibration[4]) / 100)
)
/ 64
)
/ 100
)
+ 16384
)
) / 1024
var3 = var1 * var2
var4 = self._humidity_calibration[5] * 128
var4 = (var4 + ((temp_scaled * self._humidity_calibration[6]) / 100)) / 16
var5 = ((var3 / 16384) * (var3 / 16384)) / 1024
var6 = (var4 * var5) / 2
calc_hum = (((var3 + var6) / 1024) * 1000) / 4096
calc_hum /= 1000 # get back to RH
if calc_hum > 100:
calc_hum = 100
if calc_hum < 0:
calc_hum = 0
return calc_hum
@property
def altitude(self):
"""The altitude based on current ``pressure`` vs the sea level pressure
(``sea_level_pressure``) - which you must enter ahead of time)"""
pressure = self.pressure # in Si units for hPascal
return 44330 * (1.0 - math.pow(pressure / self.sea_level_pressure, 0.1903))
@property
def gas(self):
"""The gas resistance in ohms"""
self._perform_reading()
var1 = (
(1340 + (5 * self._sw_err)) * (_LOOKUP_TABLE_1[self._gas_range])
) / 65536
var2 = ((self._adc_gas * 32768) - 16777216) + var1
var3 = (_LOOKUP_TABLE_2[self._gas_range] * var1) / 512
calc_gas_res = (var3 + (var2 / 2)) / var2
return int(calc_gas_res)
def _perform_reading(self):
"""Perform a single-shot reading from the sensor and fill internal data structure for
calculations"""
if time.monotonic() - self._last_reading < self._min_refresh_time:
return
# set filter
self._write(_BME680_REG_CONFIG, [self._filter << 2])
# turn on temp oversample & pressure oversample
self._write(
_BME680_REG_CTRL_MEAS,
[(self._temp_oversample << 5) | (self._pressure_oversample << 2)],
)
# turn on humidity oversample
self._write(_BME680_REG_CTRL_HUM, [self._humidity_oversample])
# gas measurements enabled
self._write(_BME680_REG_CTRL_GAS, [_BME680_RUNGAS])
ctrl = self._read_byte(_BME680_REG_CTRL_MEAS)
ctrl = (ctrl & 0xFC) | 0x01 # enable single shot!
self._write(_BME680_REG_CTRL_MEAS, [ctrl])
new_data = False
while not new_data:
data = self._read(_BME680_REG_MEAS_STATUS, 15)
new_data = data[0] & 0x80 != 0
time.sleep(0.005)
self._last_reading = time.monotonic()
self._adc_pres = _read24(data[2:5]) / 16
self._adc_temp = _read24(data[5:8]) / 16
self._adc_hum = struct.unpack(">H", bytes(data[8:10]))[0]
self._adc_gas = int(struct.unpack(">H", bytes(data[13:15]))[0] / 64)
self._gas_range = data[14] & 0x0F
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)
def _read_calibration(self):
"""Read & save the calibration coefficients"""
coeff = self._read(_BME680_BME680_COEFF_ADDR1, 25)
coeff += self._read(_BME680_BME680_COEFF_ADDR2, 16)
coeff = list(struct.unpack("<hbBHhbBhhbbHhhBBBHbbbBbHhbb", bytes(coeff[1:39])))
# print("\n\n",coeff)
coeff = [float(i) for i in coeff]
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]]
# flip around H1 & H2
self._humidity_calibration[1] *= 16
self._humidity_calibration[1] += self._humidity_calibration[0] % 16
self._humidity_calibration[0] /= 16
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
def _read_byte(self, register):
"""Read a byte register value and return it"""
return self._read(register, 1)[0]
def _read(self, register, length):
raise NotImplementedError()
def _write(self, register, values):
raise NotImplementedError()
[docs]class Adafruit_BME680_I2C(Adafruit_BME680):
"""Driver for I2C connected BME680.
:param int address: I2C device address
:param bool debug: Print debug statements when True.
:param int refresh_rate: Maximum number of readings per second. Faster property reads
will be from the previous reading."""
def __init__(self, i2c, address=0x77, debug=False, *, refresh_rate=10):
"""Initialize the I2C device at the 'address' given"""
from adafruit_bus_device import ( # pylint: disable=import-outside-toplevel
i2c_device,
)
self._i2c = i2c_device.I2CDevice(i2c, address)
self._debug = debug
super().__init__(refresh_rate=refresh_rate)
def _read(self, register, length):
"""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("\t$%02X => %s" % (register, [hex(i) for i in result]))
return result
def _write(self, register, values):
"""Writes an array of 'length' bytes to the 'register'"""
with self._i2c as i2c:
buffer = bytearray(2 * len(values))
for i, value in enumerate(values):
buffer[2 * i] = register + i
buffer[2 * i + 1] = value
i2c.write(buffer)
if self._debug:
print("\t$%02X <= %s" % (values[0], [hex(i) for i in values[1:]]))
[docs]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.
:param int baudrate: Clock rate, default is 100000
:param int refresh_rate: Maximum number of readings per second. Faster property reads
will be from the previous reading.
"""
def __init__(self, spi, cs, baudrate=100000, debug=False, *, refresh_rate=10):
from adafruit_bus_device import ( # pylint: disable=import-outside-toplevel
spi_device,
)
self._spi = spi_device.SPIDevice(spi, cs, baudrate=baudrate)
self._debug = debug
super().__init__(refresh_rate=refresh_rate)
def _read(self, register, length):
if register != _BME680_REG_STATUS:
# _BME680_REG_STATUS exists in both SPI memory pages
# For all other registers, we must set the correct memory page
self._set_spi_mem_page(register)
register = (register | 0x80) & 0xFF # Read single, bit 7 high.
with self._spi as spi:
spi.write(bytearray([register])) # pylint: disable=no-member
result = bytearray(length)
spi.readinto(result) # pylint: disable=no-member
if self._debug:
print("\t$%02X => %s" % (register, [hex(i) for i in result]))
return result
def _write(self, register, values):
if register != _BME680_REG_STATUS:
# _BME680_REG_STATUS exists in both SPI memory pages
# For all other registers, we must set the correct memory page
self._set_spi_mem_page(register)
register &= 0x7F # Write, bit 7 low.
with self._spi as spi:
buffer = bytearray(2 * len(values))
for i, value in enumerate(values):
buffer[2 * i] = register + i
buffer[2 * i + 1] = value & 0xFF
spi.write(buffer) # pylint: disable=no-member
if self._debug:
print("\t$%02X <= %s" % (values[0], [hex(i) for i in values[1:]]))
def _set_spi_mem_page(self, register):
spi_mem_page = 0x00
if register < 0x80:
spi_mem_page = 0x10
self._write(_BME680_REG_STATUS, [spi_mem_page])