====== BMP280 - Pressure & Temperature ====== High Precision Atmospheric Pressure Sensor Module {{:components:bmp280.png?nolink&200|}} |Operation range|Pressure: 300...1100 hPa, Temperature: -40…85°C| |Absolute accuracy (950...1050 hPa, 0…+40°C)|~ ±1 hPa| |Relative accuracy p = 700…900hPa (Temp. @ 25°C)|± 0.12 hPa (typical) equivalent to ±1 m| |Average typical current consumption (1 Hz data rate)|3.4 μA @ 1 Hz| |Average current consumption (1 Hz data refresh rate)|2.74 μA, typical, (ultra-low power mode) |Average current consumption in sleep mode|0.1 μA| |Average measurement time|5.5 msec (ultra-low power preset)| |Supply voltage VDDIO|1.2 ... 3.6 V| |Supply voltage VDD|1.71 ... 3.6 V| |Resolution of data|Pressure: 0.01 hPa ( < 10 cm), Temperature: 0.01° C| |Temperature coefficient offset (+25°…+40°C @900hPa)|1.5 Pa/K, equiv. to 12.6 cm/K| |Interface|I²C and SPI| ====== Code ====== ===== Library Integer version ===== # Updated 2018 # This module is based on the below cited resources, which are all # based on the documentation as provided in the Bosch Data Sheet and # the sample implementation provided therein. # # Final Document: BST-BME280-DS002-15 # # 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. # # Based on the documentation as provided in the Bosch Data Sheet and # the sample implementation provided therein. # Document BST-BME280-DS002-15 # 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_STATUS = 0xF3 BME280_REGISTER_CONTROL = 0xF4 MODE_SLEEP = const(0) MODE_FORCED = const(1) MODE_NORMAL = const(3) class BME280: def __init__(self, mode=BME280_OSAMPLE_8, 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_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4,' 'BME280_OSAMPLE_8, BME280_OSAMPLE_16'.format(mode)) self._mode = mode self.address = address if i2c is None: raise ValueError('An I2C object is required.') self.i2c = i2c self.__sealevel = 101325 # 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("> 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 sealevel(self): return self.__sealevel @sealevel.setter def sealevel(self, value): if 300 < value < 1200: # just ensure some reasonable value self.__sealevel = value @property def altitude(self): ''' Altitude in m. ''' from math import pow try: p = 44330 * (1.0 - pow((self.read_compensated_data()[1] / 256) / self.__sealevel, 0.1903)) except: p = 0.0 return p @property def dew_point(self): """ Compute the dew point temperature for the current Temperature and Humidity measured pair """ from math import log t, p, h = self.read_compensated_data() t /= 100 h /= 1024 h = (log(h, 10) - 2) / 0.4343 + (17.62 * t) / (243.12 + t) return (243.12 * h / (17.62 - h)) * 100 @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)) ===== Library Float version ===== # Updated 2018 # This module is based on the below cited resources, which are all # based on the documentation as provided in the Bosch Data Sheet and # the sample implementation provided therein. # # Final Document: BST-BME280-DS002-15 # # 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. # from micropython import const 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_STATUS = 0xF3 BME280_REGISTER_CONTROL = 0xF4 MODE_SLEEP = const(0) MODE_FORCED = const(1) MODE_NORMAL = const(3) class BME280: def __init__(self, mode=BME280_OSAMPLE_8, address=BME280_I2CADDR, i2c=None, tempCorrection=0, **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_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4,' 'BME280_OSAMPLE_8, BME280_OSAMPLE_16'.format(mode)) self._mode = mode self.address = address if i2c is None: raise ValueError('An I2C object is required.') self.i2c = i2c self.__sealevel = 101325 self.tempCorVal = tempCorrection # 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("> 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/16384.0 - self.dig_T1/1024.0) * self.dig_T2 var2 = raw_temp/131072.0 - self.dig_T1/8192.0 var2 = var2 * var2 * self.dig_T3 self.t_fine = int(var1 + var2) temp = (var1 + var2) / 5120.0 temp = max(-40, min(85, temp)) # pressure var1 = (self.t_fine/2.0) - 64000.0 var2 = var1 * var1 * self.dig_P6 / 32768.0 + var1 * self.dig_P5 * 2.0 var2 = (var2 / 4.0) + (self.dig_P4 * 65536.0) var1 = (self.dig_P3 * var1 * var1 / 524288.0 + self.dig_P2 * var1) / 524288.0 var1 = (1.0 + var1 / 32768.0) * self.dig_P1 if (var1 == 0.0): pressure = 30000 # avoid exception caused by division by zero else: p = ((1048576.0 - raw_press) - (var2 / 4096.0)) * 6250.0 / var1 var1 = self.dig_P9 * p * p / 2147483648.0 var2 = p * self.dig_P8 / 32768.0 pressure = p + (var1 + var2 + self.dig_P7) / 16.0 pressure = max(30000, min(110000, pressure)) # humidity h = (self.t_fine - 76800.0) h = ((raw_hum - (self.dig_H4 * 64.0 + self.dig_H5 / 16384.0 * h)) * (self.dig_H2 / 65536.0 * (1.0 + self.dig_H6 / 67108864.0 * h * (1.0 + self.dig_H3 / 67108864.0 * h)))) humidity = h * (1.0 - self.dig_H1 * h / 524288.0) # humidity = max(0, min(100, humidity)) if result: result[0] = temp result[1] = pressure result[2] = humidity return result return array("f", (temp + self.tempCorVal, pressure, humidity)) @property def sealevel(self): return self.__sealevel @sealevel.setter def sealevel(self, value): if 30000 < value < 120000: # just ensure some reasonable value self.__sealevel = value @property def altitude(self): ''' Altitude in m. ''' from math import pow try: p = 44330 * (1.0 - pow(self.read_compensated_data()[1] / self.__sealevel, 0.1903)) except: p = 0.0 return p @property def dew_point(self): """ Compute the dew point temperature for the current Temperature and Humidity measured pair """ from math import log t, p, h = self.read_compensated_data() h = (log(h, 10) - 2) / 0.4343 + (17.62 * t) / (243.12 + t) return 243.12 * h / (17.62 - h) @property def values(self): """ human readable values """ t, p, h = self.read_compensated_data() return ("{:.1f}".format(t), "{:.1f}".format(p/100), "{:.1f}".format(h))