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Content # Authors: Paul Cunnane 2016, Peter Dahlebrg 2016 # # This module borrows from the Adafruit BME280 Python library. Original # Copyright notices are reproduced below. # # Those libraries were written for the Raspberry Pi. This modification is # intended for the MicroPython and esp8266 boards. # # Copyright (c) 2014 Adafruit Industries # Author: Tony DiCola # # Based on the BMP280 driver with BME280 changes provided by # 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. import time from ustruct import unpack, unpack_from from array import array # BME280 default address. BME280_I2CADDR = 0x76 # Operating Modes BME280_OSAMPLE_1 = 1 BME280_OSAMPLE_2 = 2 BME280_OSAMPLE_4 = 3 BME280_OSAMPLE_8 = 4 BME280_OSAMPLE_16 = 5 BME280_REGISTER_CONTROL_HUM = 0xF2 BME280_REGISTER_CONTROL = 0xF4 class BME280: def __init__(self, mode=BME280_OSAMPLE_1, address=BME280_I2CADDR, i2c=None, **kwargs): # Check that mode is valid. if mode not in [BME280_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4, BME280_OSAMPLE_8, BME280_OSAMPLE_16]: raise ValueError( 'Unexpected mode value {0}. Set mode to one of ' 'BME280_ULTRALOWPOWER, BME280_STANDARD, BME280_HIGHRES, or ' 'BME280_ULTRAHIGHRES'.format(mode)) self._mode = mode self.address = address if i2c is None: raise ValueError('An I2C object is required.') self.i2c = i2c # load calibration data dig_88_a1 = self.i2c.readfrom_mem(self.address, 0x88, 26) dig_e1_e7 = self.i2c.readfrom_mem(self.address, 0xE1, 7) self.dig_T1, self.dig_T2, self.dig_T3, self.dig_P1, \ self.dig_P2, self.dig_P3, self.dig_P4, self.dig_P5, \ self.dig_P6, self.dig_P7, self.dig_P8, self.dig_P9, \ _, self.dig_H1 = unpack("<HhhHhhhhhhhhBB", dig_88_a1) self.dig_H2, self.dig_H3 = unpack("<hB", dig_e1_e7) e4_sign = unpack_from("<b", dig_e1_e7, 3)[0] self.dig_H4 = (e4_sign << 4) | (dig_e1_e7[4] & 0xF) e6_sign = unpack_from("<b", dig_e1_e7, 5)[0] self.dig_H5 = (e6_sign << 4) | (dig_e1_e7[4] >> 4) self.dig_H6 = unpack_from("<b", dig_e1_e7, 6)[0] self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL, bytearray([0x3F])) self.t_fine = 0 # temporary data holders which stay allocated self._l1_barray = bytearray(1) self._l8_barray = bytearray(8) self._l3_resultarray = array("i", [0, 0, 0]) def read_raw_data(self, result): """ 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 """ self._l1_barray[0] = self._mode self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL_HUM, self._l1_barray) self._l1_barray[0] = self._mode << 5 | self._mode << 2 | 1 self.i2c.writeto_mem(self.address, BME280_REGISTER_CONTROL, self._l1_barray) sleep_time = 1250 + 2300 * (1 << self._mode) sleep_time = sleep_time + 2300 * (1 << self._mode) + 575 sleep_time = sleep_time + 2300 * (1 << self._mode) + 575 time.sleep_us(sleep_time) # Wait the required time # burst readout from 0xF7 to 0xFE, recommended by datasheet self.i2c.readfrom_mem_into(self.address, 0xF7, self._l8_barray) readout = self._l8_barray # 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 >> 3) - (self.dig_T1 << 1)) * (self.dig_T2 >> 11) var2 = (((((raw_temp >> 4) - self.dig_T1) * ((raw_temp >> 4) - self.dig_T1)) >> 12) * self.dig_T3) >> 14 self.t_fine = var1 + var2 temp = (self.t_fine * 5 + 128) >> 8 # 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 p = (((p << 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 pi = p // 100 pd = p - pi * 100 hi = h // 1024 hd = h * 100 // 1024 - hi * 100 return ("{}C".format(t / 100), "{}.{:02d}hPa".format(pi, pd), "{}.{:02d}%".format(hi, hd)) def tph(self): """ computer readable values """ t, p, h = self.read_compensated_data() p = p // 256 pi = p // 100 pd = p - pi * 100 hi = h // 1024 hd = h * 100 // 1024 - hi * 100 return ((t / 100), (pi+ (pd/100)),(hi+ (hd/100)))