#!/usr/bin/env python # -*- coding: utf-8 -*- import smbus import time # BME280 default address. BME280_I2CADDR = 0x76 # BME280 Registers BME280_CONTROL_MEAS = 0xF4 BME280_CONTROL_HUM = 0xF2 BME280_CONFIG = 0xF5 BME280_PRESSURE = 0xF7 BME280_TEMP = 0xFA BME280_HUMIDITY = 0xFD BME280_DIG_T1 = 0x88 BME280_DIG_T2 = 0x8A BME280_DIG_T3 = 0x8C BME280_DIG_P1 = 0x8E BME280_DIG_P2 = 0x90 BME280_DIG_P3 = 0x92 BME280_DIG_P4 = 0x94 BME280_DIG_P5 = 0x96 BME280_DIG_P6 = 0x98 BME280_DIG_P7 = 0x9A BME280_DIG_P8 = 0x9C BME280_DIG_P9 = 0x9E BME280_DIG_H1 = 0xA1 BME280_DIG_H2 = 0xE1 BME280_DIG_H3 = 0xE3 BME280_DIG_H4 = 0xE4 BME280_DIG_H5 = 0xE5 BME280_DIG_H6 = 0xE7 # Oversampling Setting BME280_OVERS_T1 = 0x20 BME280_OVERS_T2 = 0x40 BME280_OVERS_T4 = 0x60 BME280_OVERS_T8 = 0x80 BME280_OVERS_T16 = 0xA0 BME280_OVERS_P1 = 0x04 BME280_OVERS_P2 = 0x08 BME280_OVERS_P4 = 0x0C BME280_OVERS_P8 = 0x10 BME280_OVERS_P16 = 0x14 BME280_OVERS_H1 = 0x01 BME280_OVERS_H2 = 0x02 BME280_OVERS_H4 = 0x03 BME280_OVERS_H8 = 0x04 BME280_OVERS_H16 = 0x05 # Power Modes. # This lib uses NORMAL mode only! #BME280_SLEEP_MODE = 0x00 #BME280_FORCED_MODE = 0x01 BME280_NORMAL_MODE = 0x03 BME280_TSB_0_5 = 0x00 BME280_TSB_62_5 = 0x20 BME280_TSB_125 = 0x40 BME280_TSB_250 = 0x60 BME280_TSB_500 = 0x80 BME280_TSB_1000 = 0xA0 BME280_TSB_2000 = 0xC0 BME280_TSB_4000 = 0xE0 BME280_FILTER_OFF = 0x00 BME280_FILTER_COEFFICIENT2 = 0x04 BME280_FILTER_COEFFICIENT4 = 0x08 BME280_FILTER_COEFFICIENT8 = 0x0C BME280_FILTER_COEFFICIENT16 = 0x10 BME280_SPI_OFF = 0x00 BME280_SPI_ON = 0x01 BME280_CONTROL_MEAS_SET = (BME280_OVERS_T16 | BME280_OVERS_P16 | BME280_NORMAL_MODE) BME280_CONTROL_HUM_SET = BME280_OVERS_H2 BME280_CONFIG_SET = (BME280_TSB_0_5 | BME280_FILTER_COEFFICIENT16 | BME280_SPI_OFF) class BME280(object): def __init__(self, port=1, address=BME280_I2CADDR): self.bus = smbus.SMBus(port) self.address = address # Read calibration values self.dig_t1 = self.read_word(BME280_DIG_T1) # Unsigned self.dig_t2 = self.read_word_sign(BME280_DIG_T2) self.dig_t3 = self.read_word_sign(BME280_DIG_T3) print "dig_t1=", self.dig_t1, "dig_t2=",self.dig_t2,"dig_t3=",self.dig_t3 self.dig_p1 = self.read_word(BME280_DIG_P1) # Unsigned self.dig_p2 = self.read_word_sign(BME280_DIG_P2) self.dig_p3 = self.read_word_sign(BME280_DIG_P3) print "dig_p1=", self.dig_p1, "dig_p2=",self.dig_p2,"dig_p3=",self.dig_p3 self.dig_p4 = self.read_word_sign(BME280_DIG_P4) self.dig_p5 = self.read_word_sign(BME280_DIG_P5) self.dig_p6 = self.read_word_sign(BME280_DIG_P6) print "dig_p4=", self.dig_p4, "dig_p5=",self.dig_p5,"dig_p6=",self.dig_p6 self.dig_p7 = self.read_word_sign(BME280_DIG_P7) self.dig_p8 = self.read_word_sign(BME280_DIG_P8) self.dig_p9 = self.read_word_sign(BME280_DIG_P9) print "dig_p7=", self.dig_p7, "dig_p8=",self.dig_p8,"dig_p9=",self.dig_p9 self.dig_h1 = self.read_byte(BME280_DIG_H1) # unsigned char self.dig_h2 = self.read_word_sign(BME280_DIG_H2) self.dig_h3 = self.read_byte(BME280_DIG_H3) # unsigned char print "dig_h1=", self.dig_h1, "dig_h2=",self.dig_h2,"dig_h3=",self.dig_h3 self.dig_h4 = (self.read_byte(BME280_DIG_H4) << 24) >> 20 self.dig_h4 = self.dig_h4 | self.read_byte(BME280_DIG_H4+1) & 0x0F self.dig_h5 = (self.read_byte(BME280_DIG_H5+1) << 24) >> 20 self.dig_h5 = self.dig_h5 | (self.read_byte(BME280_DIG_H5) >> 4) & 0x0F self.dig_h6 = self.read_byte(BME280_DIG_H6) # signed char if self.dig_h6 > 127: self.dig_h6 = 127-self.dig_h6 print "dig_h4=", self.dig_h4, "dig_h5=",self.dig_h5,"dig_h6=",self.dig_h6 # Set Configuration self.write_byte(BME280_CONFIG, BME280_CONFIG_SET) self.write_byte(BME280_CONTROL_HUM, BME280_CONTROL_HUM_SET) self.write_byte(BME280_CONTROL_MEAS, BME280_CONTROL_MEAS_SET) def get_data(self): adc_t = self.read_adc_long(BME280_TEMP) adc_p = self.read_adc_long(BME280_PRESSURE) adc_h = self.read_adc_word(BME280_HUMIDITY) var1 = (adc_t/16384.0 - self.dig_t1/1024.0) * self.dig_t2; var2 = ((adc_t/131072.0 - self.dig_t1/8192.0) * (adc_t/131072.0 - self.dig_t1/8192.0)) * self.dig_t3; t_fine = (var1 + var2); temperature = round((t_fine / 5120.0), 2); var1 = (t_fine/2.0) - 64000.0; var2 = var1 * var1 * self.dig_p6 / 32768.0; var2 = var2 + 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; # Avoid exception caused by division by zero if (var1 == 0.0): return -1 p = 1048576.0 - adc_p; p = (p - (var2 / 4096.0)) * 6250.0 / var1; var1 = self.dig_p9 * p * p / 2147483648.0; var2 = p * self.dig_p8 / 32768.0; pressure = round((p + (var1 + var2 + self.dig_p7) / 16.0), 2); var_H = t_fine - 76800.0 var_H = (adc_h-(self.dig_h4*64.0+self.dig_h5 / 16384.0 * var_H))*(self.dig_h2/65536.0 * (1.0 + self.dig_h6/67108864.0 * var_H * (1.0+self.dig_h3/67108864.0 * var_H))) humidity = round(var_H * (1.0 - self.dig_h1*var_H/524288.0), 2) print "adc_h=", adc_h if (humidity > 100.0): humidity = 100.0 else: if(humidity < 0.0): humidity = 0.0 return {'t':temperature, 'p':pressure, 'h':humidity} def get_altitude(self, pressure): temp = pressure/101325; temp = 1-pow(temp, 0.19029); altitude = round(44330*temp, 3); return altitude; def read_byte(self, adr): return self.bus.read_byte_data(self.address, adr) def read_word(self, adr): # ATANTION! Joke from Bosch! LBS before HBS. For calibration registers only! lbs = self.bus.read_byte_data(self.address, adr) hbs = self.bus.read_byte_data(self.address, adr+1) return (hbs << 8) + lbs def read_word_sign(self, adr): val = self.read_word(adr) if (val >= 0x8000): return -((65535 - val) + 1) else: return val def read_adc_long(self, adr): mbs = self.bus.read_byte_data(self.address, adr) lbs = self.bus.read_byte_data(self.address, adr+1) xbs = self.bus.read_byte_data(self.address, adr+2) val = (mbs << 16) + (lbs << 8) + xbs val = (val >> 4) return val def read_adc_word(self, adr): mbs = self.bus.read_byte_data(self.address, adr) lbs = self.bus.read_byte_data(self.address, adr+1) val = (mbs << 8) + lbs return val def write_byte(self, adr, byte): self.bus.write_byte_data(self.address, adr, byte)