kopia lustrzana https://github.com/peterhinch/mpy_bme280_esp8266
184 wiersze
6.9 KiB
Python
184 wiersze
6.9 KiB
Python
# Author: Paul Cunnane 2016
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#
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# This module borrows heavily from the Adafruit BME280 Python library
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# and the Adafruit GPIO/I2C library. Original copyright notices are reproduced
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# 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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# 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, mode=BME280_OSAMPLE_1, address=BME280_I2CADDR, 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("<HhhHhhhhhhhhB", 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)
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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)
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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)
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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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def read_raw_data(self):
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""" Reads the raw (uncompensated) data from the sensor.
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Returns:
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tuple with temperature, pressure, humidity
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"""
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meas = self._mode
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL_HUM,
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bytearray([meas]))
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meas = self._mode << 5 | self._mode << 2 | 1
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self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL,
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bytearray([meas]))
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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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readout = self.i2c.readfrom_mem(self.address, 0xF7, 8)
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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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return (raw_temp, raw_press, raw_hum)
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def read_compensated_data(self):
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""" Reads the data from the sensor and returns the compensated data.
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Returns:
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tuple with temperature, pressure, humidity
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"""
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raw_temp, raw_press, raw_hum = self.read_raw_data()
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#temperature
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var1 = ((raw_temp >> 3) - (self.dig_T1 << 1)) * (self.dig_T2 >> 11)
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var2 = ((
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(((raw_temp >> 4) - self.dig_T1) *
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((raw_temp >> 4) - self.dig_T1)) >> 12) *
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self.dig_T3) >> 14
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self.t_fine = var1 + var2
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temp = (self.t_fine * 5 + 128) >> 8
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# pressure
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var1 = self.t_fine - 128000
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var2 = var1 * var1 * self.dig_P6
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var2 = var2 + ((var1 * self.dig_P5) << 17)
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var2 = var2 + (self.dig_P4 << 35)
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var1 = (((var1 * var1 * self.dig_P3) >> 8) +
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((var1 * self.dig_P2) >> 12))
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var1 = (((1 << 47) + var1) * self.dig_P1) >> 33
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if var1 == 0:
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pressure = 0
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else:
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p = 1048576 - raw_press
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p = (((p << 31) - var2) * 3125) // var1
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var1 = (self.dig_P9 * (p >> 13) * (p >> 13)) >> 25
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var2 = (self.dig_P8 * p) >> 19
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pressure = ((p + var1 + var2) >> 8) + (self.dig_P7 << 4)
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#humidity
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h = self.t_fine - 76800
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h = (((((raw_hum << 14) - (self.dig_H4 << 20) - (self.dig_H5 * h)) +
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16384) >> 15) * (((((((h * self.dig_H6) >> 10) * (((h *
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self.dig_H3) >> 11) + 32768)) >> 10) + 2097152) *
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self.dig_H2 + 8192) >> 14))
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h = h - (((((h >> 15) * (h >> 15)) >> 7) * self.dig_H1) >> 4)
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h = 0 if h < 0 else h
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h = 419430400 if h > 419430400 else h
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humidity = h >> 12
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return (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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ti = t // 100
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td = t - ti * 100
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p = p // 256
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pi = p // 100
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pd = p - pi * 100
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hi = h // 1024
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hd = h * 100 // 1024 - hi * 100
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return ("{}.{:02d}C".format(ti, td), "{}.{:02d}hPa".format(pi, pd),
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"{}.{:02d}%".format(hi, hd))
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