kopia lustrzana https://github.com/robert-hh/BME280
bme280_xxx.py: Microypthon driver for the BME280 sensor
Initial commit. Files: bme280_int.py: Driver using integer arithmetic for compensation bme280_float.py: Driver using floating point arithmetic for compensation README.md: Documentation bmetest.py: Sample test code.pull/6/head
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# BME280 Micropython driver for the BME280 sensor
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This is a driver for the Bosch BME280 temperature/pressure/humidity sensor,
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for use with MicroPython on Pycom of ESP8266 boards. It is also compatible with
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the BMP280 which provides the same interface but temperature + pressure only.
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Two different variants of the library are supplied. bme20_int.py uses integer
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arithmetic. bme280_float.py uses float arithmetic for the compensation of the
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raw values. The results are (almost) the identical, but the format of the
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returned values differs.
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## About the BME280
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The Bosch BME280 Environmental Sensor is a combined temperature, pressure and
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humidity sensor. It can communicate via I2C or SPI; this driver uses I2C.
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See the datasheet at https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS002.pdf
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for details.
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## Class
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bme= BME280(i2c=i2c, mode=BME280_OSAMPLE_8, address=BME280_I2CADDR)
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mode is the setting for oversampling of the humidity value, address the i2c
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address used.
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## Property
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### values = BME280.value
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The `values` property is a convenience function that provides a tuple of
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human-readable string values to quickly check that the sensor is working.
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In practice, the method to use is `read_compensated_data()` which returns
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a `(temperature, pressure, humidity)`-tuple
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## Methods
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### values = read_compensated_data(result = None)
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Values is an array of either integers of floats, holding the values of temperature,
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pressure and humidity. The format differs for integers and floats:
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#### Integer formats:
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* `temperature`: the temperature in hundredths of a degree Celsius. For example,
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the value 2534 indicates a temperature of 25.34 degrees.
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* `pressure`: the atmospheric pressure. This 32-bit value consists of 24 bits
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indicating the integer value, and 8 bits indicating the fractional value. To get
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a value in Pascals, divide the return value by 256. For example, a value of
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24674867 indicates 96386.2Pa, or 963.862hPa.
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* `humidity`: the relative humidity. This 32-bit value consists of 22 bits
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indicating the integer value, and 10 bits indicating the fractional value.
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To get a value in %RH, divide the return value by 1024. For example, a value of
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47445 indicates 46.333%RH.
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#### Float formats
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* `temperature`: the temperature in degree Celsius.
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* `pressure`: the atmospheric pressure in Pascal.
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* `humidity`: the relative humidity in percent.
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If the parameter result is supplied as an array of the appropriate type, The
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return values will in addition be stored in that array, and the array will be
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returned.
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### read_raw_data(result)
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Store the raw sensor data into the array result, which must provide space for three
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32 bit integers, as provided for instance by `array("i", [0, 0, 0])`. This
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method is used internally.
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### Example
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Copy `bme280.py` onto the board. Then:
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``` python
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#
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# this script assumes the default connection of the I2C bus
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# On pycom devuces that is P9 = SDA, P10 = scl
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#
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import machine
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import bme280
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i2c = machine.I2C()
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bme = bme280.BME280(i2c=i2c)
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print(bme.values)
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```
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# Authors: Paul Cunnane 2016, Peter Dahlebrg 2016
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#
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# This module borrows from the Adafruit BME280 Python library. Original
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# Copyright notices are reproduced below.
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#
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# Those libraries were written for the Raspberry Pi. This modification is
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# intended for the MicroPython and esp8266 boards.
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#
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# Copyright (c) 2014 Adafruit Industries
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# Author: Tony DiCola
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#
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# Based on the BMP280 driver with BME280 changes provided by
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# David J Taylor, Edinburgh (www.satsignal.eu)
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#
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# Based on Adafruit_I2C.py created by Kevin Townsend.
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
|
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
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# copies of the Software, and to permit persons to whom the Software is
|
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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import time
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from ustruct import unpack, unpack_from
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from array import array
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# BME280 default address.
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BME280_I2CADDR = 0x76
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# Operating Modes
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BME280_OSAMPLE_1 = 1
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BME280_OSAMPLE_2 = 2
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BME280_OSAMPLE_4 = 3
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BME280_OSAMPLE_8 = 4
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BME280_OSAMPLE_16 = 5
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BME280_REGISTER_CONTROL_HUM = 0xF2
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BME280_REGISTER_CONTROL = 0xF4
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class BME280:
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def __init__(self,
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mode=BME280_OSAMPLE_8,
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address=BME280_I2CADDR,
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i2c=None,
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**kwargs):
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# Check that mode is valid.
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if mode not in [BME280_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4,
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BME280_OSAMPLE_8, BME280_OSAMPLE_16]:
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raise ValueError(
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'Unexpected mode value {0}. Set mode to one of '
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'BME280_ULTRALOWPOWER, BME280_STANDARD, BME280_HIGHRES, or '
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'BME280_ULTRAHIGHRES'.format(mode))
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self._mode = mode
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self.address = address
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if i2c is None:
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raise ValueError('An I2C object is required.')
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self.i2c = i2c
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# load calibration data
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dig_88_a1 = self.i2c.readfrom_mem(self.address, 0x88, 26)
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dig_e1_e7 = self.i2c.readfrom_mem(self.address, 0xE1, 7)
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self.dig_T1, self.dig_T2, self.dig_T3, self.dig_P1, \
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self.dig_P2, self.dig_P3, self.dig_P4, self.dig_P5, \
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self.dig_P6, self.dig_P7, self.dig_P8, self.dig_P9, \
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_, self.dig_H1 = unpack("<HhhHhhhhhhhhBB", dig_88_a1)
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self.dig_H2, self.dig_H3 = unpack("<hB", dig_e1_e7)
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e4_sign = unpack_from("<b", dig_e1_e7, 3)[0]
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self.dig_H4 = (e4_sign << 4) | (dig_e1_e7[4] & 0xF)
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e6_sign = unpack_from("<b", dig_e1_e7, 5)[0]
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self.dig_H5 = (e6_sign << 4) | ((dig_e1_e7[4] >> 4) & 0x0F)
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self.dig_H6 = unpack_from("<b", dig_e1_e7, 6)[0]
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL,
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bytearray([0x3F]))
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self.t_fine = 0
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# temporary data holders which stay allocated
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self._l1_barray = bytearray(1)
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self._l8_barray = bytearray(8)
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self._l3_resultarray = array("i", [0, 0, 0])
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def read_raw_data(self, result):
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""" Reads the raw (uncompensated) data from the sensor.
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Args:
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result: array of length 3 or alike where the result will be
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stored, in temperature, pressure, humidity order
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Returns:
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None
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"""
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self._l1_barray[0] = self._mode
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL_HUM,
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self._l1_barray)
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self._l1_barray[0] = self._mode << 5 | self._mode << 2 | 1
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL,
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self._l1_barray)
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sleep_time = 1250 + 2300 * (1 << self._mode)
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sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
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sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
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time.sleep_us(sleep_time) # Wait the required time
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# burst readout from 0xF7 to 0xFE, recommended by datasheet
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self.i2c.readfrom_mem_into(self.address, 0xF7, self._l8_barray)
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readout = self._l8_barray
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# pressure(0xF7): ((msb << 16) | (lsb << 8) | xlsb) >> 4
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raw_press = ((readout[0] << 16) | (readout[1] << 8) | readout[2]) >> 4
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# temperature(0xFA): ((msb << 16) | (lsb << 8) | xlsb) >> 4
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raw_temp = ((readout[3] << 16) | (readout[4] << 8) | readout[5]) >> 4
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# humidity(0xFD): (msb << 8) | lsb
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raw_hum = (readout[6] << 8) | readout[7]
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result[0] = raw_temp
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result[1] = raw_press
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result[2] = raw_hum
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def read_compensated_data(self, result=None):
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""" Reads the data from the sensor and returns the compensated data.
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Args:
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result: array of length 3 or alike where the result will be
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stored, in temperature, pressure, humidity order. You may use
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this to read out the sensor without allocating heap memory
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Returns:
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array with temperature, pressure, humidity. Will be the one from
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the result parameter if not None
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"""
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self.read_raw_data(self._l3_resultarray)
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raw_temp, raw_press, raw_hum = self._l3_resultarray
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# temperature
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var1 = (raw_temp/16384.0 - self.dig_T1/1024.0) * self.dig_T2
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var2 = raw_temp/131072.0 - self.dig_T1/8192.0
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var2 = var2 * var2 * self.dig_T3
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self.t_fine = int(var1 + var2)
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temp = (var1 + var2) / 5120.0
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temp = max(-40, min(85, temp))
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# pressure
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var1 = (self.t_fine/2.0) - 64000.0
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var2 = var1 * var1 * self.dig_P6 / 32768.0 + var1 * self.dig_P5 * 2.0
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var2 = (var2 / 4.0) + (self.dig_P4 * 65536.0)
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var1 = (self.dig_P3 * var1 * var1 / 524288.0 + self.dig_P2 * var1) / 524288.0
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var1 = (1.0 + var1 / 32768.0) * self.dig_P1
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if (var1 == 0.0):
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pressure = 30000 # avoid exception caused by division by zero
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else:
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p = ((1048576.0 - raw_press) - (var2 / 4096.0)) * 6250.0 / var1
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var1 = self.dig_P9 * p * p / 2147483648.0
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var2 = p * self.dig_P8 / 32768.0
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pressure = p + (var1 + var2 + self.dig_P7) / 16.0
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pressure = max(30000, min(110000, pressure))
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# humidity
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h = (self.t_fine - 76800.0)
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h = ((raw_hum - (self.dig_H4 * 64.0 + self.dig_H5 / 16384.0 * h)) *
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(self.dig_H2 / 65536.0 * (1.0 + self.dig_H6 / 67108864.0 * h *
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(1.0 + self.dig_H3 / 67108864.0 * h))))
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humidity = h * (1.0 - self.dig_H1 * h / 524288.0)
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humidity = max(0, min(100, humidity))
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if result:
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result[0] = temp
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result[1] = pressure
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result[2] = humidity
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return result
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return array("f", (temp, pressure, humidity))
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@property
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def values(self):
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""" human readable values """
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t, p, h = self.read_compensated_data()
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return ("{:.2f}C".format(t), "{:.2f}hPa".format(p/100),
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"{:.2f}%".format(h))
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@ -0,0 +1,203 @@
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# Authors: Paul Cunnane 2016, Peter Dahlebrg 2016
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#
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# This module borrows from the Adafruit BME280 Python library. Original
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||||
# Copyright notices are reproduced below.
|
||||
#
|
||||
# Those libraries were written for the Raspberry Pi. This modification is
|
||||
# intended for the MicroPython and esp8266 boards.
|
||||
#
|
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# Copyright (c) 2014 Adafruit Industries
|
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# Author: Tony DiCola
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#
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# Based on the BMP280 driver with BME280 changes provided by
|
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# David J Taylor, Edinburgh (www.satsignal.eu)
|
||||
#
|
||||
# Based on Adafruit_I2C.py created by Kevin Townsend.
|
||||
#
|
||||
# Permission is hereby granted, free of charge, to any person obtaining a copy
|
||||
# of this software and associated documentation files (the "Software"), to deal
|
||||
# in the Software without restriction, including without limitation the rights
|
||||
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
||||
# copies of the Software, and to permit persons to whom the Software is
|
||||
# furnished to do so, subject to the following conditions:
|
||||
#
|
||||
# The above copyright notice and this permission notice shall be included in
|
||||
# all copies or substantial portions of the Software.
|
||||
#
|
||||
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||||
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
||||
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
||||
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
||||
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
||||
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
||||
# THE SOFTWARE.
|
||||
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import time
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from ustruct import unpack, unpack_from
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from array import array
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# BME280 default address.
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BME280_I2CADDR = 0x76
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# Operating Modes
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BME280_OSAMPLE_1 = 1
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BME280_OSAMPLE_2 = 2
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BME280_OSAMPLE_4 = 3
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BME280_OSAMPLE_8 = 4
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BME280_OSAMPLE_16 = 5
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BME280_REGISTER_CONTROL_HUM = 0xF2
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BME280_REGISTER_CONTROL = 0xF4
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class BME280:
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def __init__(self,
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mode=BME280_OSAMPLE_8,
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address=BME280_I2CADDR,
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i2c=None,
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**kwargs):
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# Check that mode is valid.
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if mode not in [BME280_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4,
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BME280_OSAMPLE_8, BME280_OSAMPLE_16]:
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raise ValueError(
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'Unexpected mode value {0}. Set mode to one of '
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'BME280_ULTRALOWPOWER, BME280_STANDARD, BME280_HIGHRES, or '
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'BME280_ULTRAHIGHRES'.format(mode))
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self._mode = mode
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self.address = address
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if i2c is None:
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raise ValueError('An I2C object is required.')
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self.i2c = i2c
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# load calibration data
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dig_88_a1 = self.i2c.readfrom_mem(self.address, 0x88, 26)
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dig_e1_e7 = self.i2c.readfrom_mem(self.address, 0xE1, 7)
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self.dig_T1, self.dig_T2, self.dig_T3, self.dig_P1, \
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self.dig_P2, self.dig_P3, self.dig_P4, self.dig_P5, \
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self.dig_P6, self.dig_P7, self.dig_P8, self.dig_P9, \
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_, self.dig_H1 = unpack("<HhhHhhhhhhhhBB", dig_88_a1)
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self.dig_H2, self.dig_H3 = unpack("<hB", dig_e1_e7)
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e4_sign = unpack_from("<b", dig_e1_e7, 3)[0]
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self.dig_H4 = (e4_sign << 4) | (dig_e1_e7[4] & 0xF)
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e6_sign = unpack_from("<b", dig_e1_e7, 5)[0]
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self.dig_H5 = (e6_sign << 4) | (dig_e1_e7[4] >> 4)
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self.dig_H6 = unpack_from("<b", dig_e1_e7, 6)[0]
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL,
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bytearray([0x3F]))
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self.t_fine = 0
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# temporary data holders which stay allocated
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self._l1_barray = bytearray(1)
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self._l8_barray = bytearray(8)
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self._l3_resultarray = array("i", [0, 0, 0])
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def read_raw_data(self, result):
|
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""" Reads the raw (uncompensated) data from the sensor.
|
||||
|
||||
Args:
|
||||
result: array of length 3 or alike where the result will be
|
||||
stored, in temperature, pressure, humidity order
|
||||
Returns:
|
||||
None
|
||||
"""
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self._l1_barray[0] = self._mode
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL_HUM,
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self._l1_barray)
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self._l1_barray[0] = self._mode << 5 | self._mode << 2 | 1
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL,
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self._l1_barray)
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sleep_time = 1250 + 2300 * (1 << self._mode)
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sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
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sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
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time.sleep_us(sleep_time) # Wait the required time
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# burst readout from 0xF7 to 0xFE, recommended by datasheet
|
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self.i2c.readfrom_mem_into(self.address, 0xF7, self._l8_barray)
|
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readout = self._l8_barray
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# pressure(0xF7): ((msb << 16) | (lsb << 8) | xlsb) >> 4
|
||||
raw_press = ((readout[0] << 16) | (readout[1] << 8) | readout[2]) >> 4
|
||||
# temperature(0xFA): ((msb << 16) | (lsb << 8) | xlsb) >> 4
|
||||
raw_temp = ((readout[3] << 16) | (readout[4] << 8) | readout[5]) >> 4
|
||||
# humidity(0xFD): (msb << 8) | lsb
|
||||
raw_hum = (readout[6] << 8) | readout[7]
|
||||
|
||||
result[0] = raw_temp
|
||||
result[1] = raw_press
|
||||
result[2] = raw_hum
|
||||
|
||||
def read_compensated_data(self, result=None):
|
||||
""" Reads the data from the sensor and returns the compensated data.
|
||||
|
||||
Args:
|
||||
result: array of length 3 or alike where the result will be
|
||||
stored, in temperature, pressure, humidity order. You may use
|
||||
this to read out the sensor without allocating heap memory
|
||||
|
||||
Returns:
|
||||
array with temperature, pressure, humidity. Will be the one from
|
||||
the result parameter if not None
|
||||
"""
|
||||
self.read_raw_data(self._l3_resultarray)
|
||||
raw_temp, raw_press, raw_hum = self._l3_resultarray
|
||||
# temperature
|
||||
var1 = (((raw_temp // 8) - (self.dig_T1 * 2)) * self.dig_T2) // 2048
|
||||
var2 = (raw_temp // 16) - self.dig_T1
|
||||
var2 = (((var2 * var2) // 4096) * self.dig_T3) // 16384
|
||||
self.t_fine = var1 + var2
|
||||
temp = (self.t_fine * 5 + 128) // 256
|
||||
|
||||
# pressure
|
||||
var1 = self.t_fine - 128000
|
||||
var2 = var1 * var1 * self.dig_P6
|
||||
var2 = var2 + ((var1 * self.dig_P5) << 17)
|
||||
var2 = var2 + (self.dig_P4 << 35)
|
||||
var1 = (((var1 * var1 * self.dig_P3) >> 8) +
|
||||
((var1 * self.dig_P2) << 12))
|
||||
var1 = (((1 << 47) + var1) * self.dig_P1) >> 33
|
||||
if var1 == 0:
|
||||
pressure = 0
|
||||
else:
|
||||
p = ((((1048576 - raw_press) << 31) - var2) * 3125) // var1
|
||||
var1 = (self.dig_P9 * (p >> 13) * (p >> 13)) >> 25
|
||||
var2 = (self.dig_P8 * p) >> 19
|
||||
pressure = ((p + var1 + var2) >> 8) + (self.dig_P7 << 4)
|
||||
|
||||
# humidity
|
||||
h = self.t_fine - 76800
|
||||
h = (((((raw_hum << 14) - (self.dig_H4 << 20) -
|
||||
(self.dig_H5 * h)) + 16384)
|
||||
>> 15) * (((((((h * self.dig_H6) >> 10) *
|
||||
(((h * self.dig_H3) >> 11) + 32768)) >> 10) +
|
||||
2097152) * self.dig_H2 + 8192) >> 14))
|
||||
h = h - (((((h >> 15) * (h >> 15)) >> 7) * self.dig_H1) >> 4)
|
||||
h = 0 if h < 0 else h
|
||||
h = 419430400 if h > 419430400 else h
|
||||
humidity = h >> 12
|
||||
|
||||
if result:
|
||||
result[0] = temp
|
||||
result[1] = pressure
|
||||
result[2] = humidity
|
||||
return result
|
||||
|
||||
return array("i", (temp, pressure, humidity))
|
||||
|
||||
@property
|
||||
def values(self):
|
||||
""" human readable values """
|
||||
|
||||
t, p, h = self.read_compensated_data()
|
||||
|
||||
p = p / 256
|
||||
|
||||
h = h / 1024
|
||||
return ("{}C".format(t / 100), "{:.02f}hPa".format(p/100),
|
||||
"{:.02f}%".format(h))
|
||||
|
||||
|
|
@ -0,0 +1,9 @@
|
|||
#
|
||||
# Example. Using I2C at P9, P10
|
||||
#
|
||||
from machine import I2C
|
||||
from bme280 import *
|
||||
i2c=I2C()
|
||||
bme280 = BME280(i2c=i2c)
|
||||
bme280.values
|
||||
|
||||
Ładowanie…
Reference in New Issue