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)
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)
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}