Python • BME280, convert temp C to F

Code:

from machine import I2Cimport time# BME280 default address.BME280_I2CADDR = 0x76# Operating ModesBME280_OSAMPLE_1 = 1BME280_OSAMPLE_2 = 2BME280_OSAMPLE_4 = 3BME280_OSAMPLE_8 = 4BME280_OSAMPLE_16 = 5# BME280 RegistersBME280_REGISTER_DIG_T1 = 0x88  # Trimming parameter registersBME280_REGISTER_DIG_T2 = 0x8ABME280_REGISTER_DIG_T3 = 0x8CBME280_REGISTER_DIG_P1 = 0x8EBME280_REGISTER_DIG_P2 = 0x90BME280_REGISTER_DIG_P3 = 0x92BME280_REGISTER_DIG_P4 = 0x94BME280_REGISTER_DIG_P5 = 0x96BME280_REGISTER_DIG_P6 = 0x98BME280_REGISTER_DIG_P7 = 0x9ABME280_REGISTER_DIG_P8 = 0x9CBME280_REGISTER_DIG_P9 = 0x9EBME280_REGISTER_DIG_H1 = 0xA1BME280_REGISTER_DIG_H2 = 0xE1BME280_REGISTER_DIG_H3 = 0xE3BME280_REGISTER_DIG_H4 = 0xE4BME280_REGISTER_DIG_H5 = 0xE5BME280_REGISTER_DIG_H6 = 0xE6BME280_REGISTER_DIG_H7 = 0xE7BME280_REGISTER_CHIPID = 0xD0BME280_REGISTER_VERSION = 0xD1BME280_REGISTER_SOFTRESET = 0xE0BME280_REGISTER_CONTROL_HUM = 0xF2BME280_REGISTER_CONTROL = 0xF4BME280_REGISTER_CONFIG = 0xF5BME280_REGISTER_PRESSURE_DATA = 0xF7BME280_REGISTER_TEMP_DATA = 0xFABME280_REGISTER_HUMIDITY_DATA = 0xFDclass Device:  """Class for communicating with an I2C device.  Allows reading and writing 8-bit, 16-bit, and byte array values to  registers on the device."""  def __init__(self, address, i2c):    """Create an instance of the I2C device at the specified address using    the specified I2C interface object."""    self._address = address    self._i2c = i2c  def writeRaw8(self, value):    """Write an 8-bit value on the bus (without register)."""    value = value & 0xFF    self._i2c.writeto(self._address, value)  def write8(self, register, value):    """Write an 8-bit value to the specified register."""    b=bytearray(1)    b[0]=value & 0xFF    self._i2c.writeto_mem(self._address, register, b)  def write16(self, register, value):    """Write a 16-bit value to the specified register."""    value = value & 0xFFFF    b=bytearray(2)    b[0]= value & 0xFF    b[1]= (value>>8) & 0xFF    self.i2c.writeto_mem(self._address, register, value)  def readRaw8(self):    """Read an 8-bit value on the bus (without register)."""    return int.from_bytes(self._i2c.readfrom(self._address, 1),'little') & 0xFF  def readU8(self, register):    """Read an unsigned byte from the specified register."""    return int.from_bytes(        self._i2c.readfrom_mem(self._address, register, 1),'little') & 0xFF  def readS8(self, register):    """Read a signed byte from the specified register."""    result = self.readU8(register)    if result > 127:      result -= 256    return result  def readU16(self, register, little_endian=True):    """Read an unsigned 16-bit value from the specified register, with the    specified endianness (default little endian, or least significant byte    first)."""    result = int.from_bytes(        self._i2c.readfrom_mem(self._address, register, 2),'little') & 0xFFFF    if not little_endian:      result = ((result << 8) & 0xFF00) + (result >> 8)    return result  def readS16(self, register, little_endian=True):    """Read a signed 16-bit value from the specified register, with the    specified endianness (default little endian, or least significant byte    first)."""    result = self.readU16(register, little_endian)    if result > 32767:      result -= 65536    return result  def readU16LE(self, register):    """Read an unsigned 16-bit value from the specified register, in little    endian byte order."""    return self.readU16(register, little_endian=True)  def readU16BE(self, register):    """Read an unsigned 16-bit value from the specified register, in big    endian byte order."""    return self.readU16(register, little_endian=False)  def readS16LE(self, register):    """Read a signed 16-bit value from the specified register, in little    endian byte order."""    return self.readS16(register, little_endian=True)  def readS16BE(self, register):    """Read a signed 16-bit value from the specified register, in big    endian byte order."""    return self.readS16(register, little_endian=False)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    # Create I2C device.    if i2c is None:      raise ValueError('An I2C object is required.')    self._device = Device(address, i2c)    # Load calibration values.    self._load_calibration()    self._device.write8(BME280_REGISTER_CONTROL, 0x3F)    self.t_fine = 0  def _load_calibration(self):    self.dig_T1 = self._device.readU16LE(BME280_REGISTER_DIG_T1)    self.dig_T2 = self._device.readS16LE(BME280_REGISTER_DIG_T2)    self.dig_T3 = self._device.readS16LE(BME280_REGISTER_DIG_T3)    self.dig_P1 = self._device.readU16LE(BME280_REGISTER_DIG_P1)    self.dig_P2 = self._device.readS16LE(BME280_REGISTER_DIG_P2)    self.dig_P3 = self._device.readS16LE(BME280_REGISTER_DIG_P3)    self.dig_P4 = self._device.readS16LE(BME280_REGISTER_DIG_P4)    self.dig_P5 = self._device.readS16LE(BME280_REGISTER_DIG_P5)    self.dig_P6 = self._device.readS16LE(BME280_REGISTER_DIG_P6)    self.dig_P7 = self._device.readS16LE(BME280_REGISTER_DIG_P7)    self.dig_P8 = self._device.readS16LE(BME280_REGISTER_DIG_P8)    self.dig_P9 = self._device.readS16LE(BME280_REGISTER_DIG_P9)    self.dig_H1 = self._device.readU8(BME280_REGISTER_DIG_H1)    self.dig_H2 = self._device.readS16LE(BME280_REGISTER_DIG_H2)    self.dig_H3 = self._device.readU8(BME280_REGISTER_DIG_H3)    self.dig_H6 = self._device.readS8(BME280_REGISTER_DIG_H7)    h4 = self._device.readS8(BME280_REGISTER_DIG_H4)    h4 = (h4 << 24) >> 20    self.dig_H4 = h4 | (self._device.readU8(BME280_REGISTER_DIG_H5) & 0x0F)    h5 = self._device.readS8(BME280_REGISTER_DIG_H6)    h5 = (h5 << 24) >> 20    self.dig_H5 = h5 | (        self._device.readU8(BME280_REGISTER_DIG_H5) >> 4 & 0x0F)  def read_raw_temp(self):    """Reads the raw (uncompensated) temperature from the sensor."""    meas = self._mode    self._device.write8(BME280_REGISTER_CONTROL_HUM, meas)    meas = self._mode << 5 | self._mode << 2 | 1    self._device.write8(BME280_REGISTER_CONTROL, meas)    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    msb = self._device.readU8(BME280_REGISTER_TEMP_DATA)    lsb = self._device.readU8(BME280_REGISTER_TEMP_DATA + 1)    xlsb = self._device.readU8(BME280_REGISTER_TEMP_DATA + 2)    raw = ((msb << 16) | (lsb << 8) | xlsb) >> 4    return raw  def read_raw_pressure(self):    """Reads the raw (uncompensated) pressure level from the sensor."""    """Assumes that the temperature has already been read """    """i.e. that enough delay has been provided"""    msb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA)    lsb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA + 1)    xlsb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA + 2)    raw = ((msb << 16) | (lsb << 8) | xlsb) >> 4    return raw  def read_raw_humidity(self):    """Assumes that the temperature has already been read """    """i.e. that enough delay has been provided"""    msb = self._device.readU8(BME280_REGISTER_HUMIDITY_DATA)    lsb = self._device.readU8(BME280_REGISTER_HUMIDITY_DATA + 1)    raw = (msb << 8) | lsb    return raw  def read_temperature(self):    """Get the compensated temperature in 0.01 of a degree celsius."""    adc = self.read_raw_temp()    var1 = ((adc >> 3) - (self.dig_T1 << 1)) * (self.dig_T2 >> 11)    var2 = ((        (((adc >> 4) - self.dig_T1) * ((adc >> 4) - self.dig_T1)) >> 12) *        self.dig_T3) >> 14    self.t_fine = var1 + var2    return (self.t_fine * 5 + 128) >> 8  def read_pressure(self):    """Gets the compensated pressure in Pascals."""    adc = self.read_raw_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:      return 0    p = 1048576 - adc    p = (((p << 31) - var2) * 3125) // var1    var1 = (self.dig_P9 * (p >> 13) * (p >> 13)) >> 25    var2 = (self.dig_P8 * p) >> 19    return ((p + var1 + var2) >> 8) + (self.dig_P7 << 4)  def read_humidity(self):    adc = self.read_raw_humidity()    # print 'Raw humidity = {0:d}'.format (adc)    h = self.t_fine - 76800    h = (((((adc << 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    return h >> 12  @property  def temperature(self):    "Return the temperature in degrees."    t = self.read_temperature()    ti = t // 100    td = t - ti * 100    return "{}.{:02d}C".format(ti, td)  @property  def pressure(self):    "Return the temperature in hPa."    p = self.read_pressure() // 256    pi = p // 100    pd = p - pi * 100    return "{}.{:02d}hPa".format(pi, pd)  @property  def humidity(self):    "Return the humidity in percent."    h = self.read_humidity()    hi = h // 1024    hd = h * 100 // 1024 - hi * 100    return "{}.{:02d}%".format(hi, hd)

Code:

  def read_temperature(self):    """Get the compensated temperature in 0.01 of a degree celsius."""    adc = self.read_raw_temp()    var1 = ((adc >> 3) - (self.dig_T1 << 1)) * (self.dig_T2 >> 11)    var2 = ((        (((adc >> 4) - self.dig_T1) * ((adc >> 4) - self.dig_T1)) >> 12) *        self.dig_T3) >> 14    self.t_fine = var1 + var2    return (self.t_fine * 5 + 128) >> 8