Example #1
0
 def get_humidity(self):
     """Reads the humidity from the sensor. This call blocks
     for 250ms to allow the sensor to return the data"""
     self.transaction(
         writing_bytes(self._I2C_ADDRESS, self._CMD_HUMIDITY_NO_HOLD))
     time.sleep(0.250)
     data = self.transaction(reading(self._I2C_ADDRESS, 3))[0]
     if _calculate_checksum(data, 2) != data[2]:
         raise ChecksumFailedError("Humidity checksum failed.")
     else:
         return _get_humidity_from_buffer(data)
 def get_humidity(self):
     """Reads the humidity from the sensor. This call blocks
     for 250ms to allow the sensor to return the data"""
     self.transaction(
         writing_bytes(self._I2C_ADDRESS,
                       self._CMD_HUMIDITY_NO_HOLD))
     time.sleep(0.250)
     data = self.transaction(reading(self._I2C_ADDRESS, 3))[0]
     if _calculate_checksum(data, 2) != data[2]:
         raise ChecksumFailedError("Humidity checksum failed.")
     else:
         return _get_humidity_from_buffer(data)
Example #3
0
 def get_temperature(self):
     """Reads the temperature from the sensor. This call blocks
     for 250ms to allow the sensor to return the data.
     """
     self.transaction(
         writing_bytes(self._I2C_ADDRESS, self._CMD_TEMPERATURE_NO_HOLD))
     time.sleep(0.250)
     data = self.transaction(reading(self._I2C_ADDRESS, 3))[0]
     if _calculate_checksum(data, 2) != data[2]:
         raise ChecksumFailedError("Temperature checksum failed.")
     else:
         return _get_temperature_from_buffer(data)
 def get_temperature(self):
     """Reads the temperature from the sensor. This call blocks
     for 250ms to allow the sensor to return the data.
     """
     self.transaction(
         writing_bytes(self._I2C_ADDRESS,
                       self._CMD_TEMPERATURE_NO_HOLD))
     time.sleep(0.250)
     data = self.transaction(reading(self._I2C_ADDRESS, 3))[0]
     if _calculate_checksum(data, 2) != data[2]:
         raise ChecksumFailedError("Temperature checksum failed.")
     else:
         return _get_temperature_from_buffer(data)
Example #5
0
    def get_xyz(self, raw=False, res12=True):
        """Returns the x, y and z values as a dictionary. By default it returns
        signed values at 12-bit resolution. You can specify a lower resolution
        (8-bit) or request the raw register values. Signed values are
        in G's. You can alter the recording range with `set_g_range()`.

        :param raw: If True: return raw, unsigned data, else: sign values
        :type raw: boolean (default: False)
        :param res12: If True: read 12-bit resolution, else: 8-bit
        :type res12: boolean (default: True)
        """
        # Since we can't read arbitary registers from this chip over I2C
        # (because there is no decent SMBus implementation, in Python 3 at
        # least) we have to just read the first 7 registers and pull the
        # XYZ data from that.

        # Notes:

        # - 12-bit resolution from OUT MSB and OUT LSB registers:

        #     +--------+-----------------+
        #     | msb    | lsb             |
        #     +--------+--------+--------+
        #     | 8 bits | 4 bits | 4 bits |
        #     +--------+--------+--------+
        #     | value (12 bits) | unused |
        #     +--------+--------+--------+

        # - 8-bit resolution just from OUT MSB:

        #     +--------+--------+
        #     | msb    | lsb    |
        #     +--------+--------+
        #     | 8 bits | 8 bits |
        #     +--------+--------+
        #     | value  | unused |
        #     +--------+--------+

        # bulk read works
        buf = self.transaction(reading(self.i2c_address, 7))[0]
        # status = buf[0]
        if res12:
            x = (buf[1] << 4) | (buf[2] >> 4)
            y = (buf[3] << 4) | (buf[4] >> 4)
            z = (buf[5] << 4) | (buf[6] >> 4)
        else:
            x, y, z = buf[1], buf[3], buf[5]

        if not raw:
            # get range
            fsr = self._xyz_data_cfg_value & 0x03
            g_ranges = {XYZ_DATA_CFG_FSR_2G: 2,
                        XYZ_DATA_CFG_FSR_4G: 4,
                        XYZ_DATA_CFG_FSR_8G: 8}
            g_range = g_ranges[fsr]
            resolution = 12 if res12 else 8
            gmul = g_range / (2 ** (resolution - 1))
            x = twos_complement(x, resolution) * gmul
            y = twos_complement(y, resolution) * gmul
            z = twos_complement(z, resolution) * gmul

        return {'x': x, 'y': y, 'z': z}