def load_calibration_params(bus, address=DEFAULT_PORT):
"""
The BME280 output consists of the ADC output values. However, each sensing
element behaves differently. Therefore, the actual pressure and temperature
must be calculated using a set of calibration parameters.
The calibration parameters are subsequently used to with some compensation
formula to perform temperature readout in degC, humidity in % and pressure
in hPA.
"""
read = reader(bus, address)
compensation_params = params()
# Temperature trimming params
compensation_params.dig_T1 = read.unsigned_short(0x88)
compensation_params.dig_T2 = read.signed_short(0x8A)
compensation_params.dig_T3 = read.signed_short(0x8C)
# Pressure trimming params
compensation_params.dig_P1 = read.unsigned_short(0x8E)
compensation_params.dig_P2 = read.signed_short(0x90)
compensation_params.dig_P3 = read.signed_short(0x92)
compensation_params.dig_P4 = read.signed_short(0x94)
compensation_params.dig_P5 = read.signed_short(0x96)
compensation_params.dig_P6 = read.signed_short(0x98)
compensation_params.dig_P7 = read.signed_short(0x9A)
compensation_params.dig_P8 = read.signed_short(0x9C)
compensation_params.dig_P9 = read.signed_short(0x9E)
# Humidity trimming params
compensation_params.dig_H1 = read.unsigned_byte(0xA1)
compensation_params.dig_H2 = read.signed_short(0xE1)
compensation_params.dig_H3 = read.signed_byte(0xE3)
e4 = read.signed_byte(0xE4)
e5 = read.signed_byte(0xE5)
e6 = read.signed_byte(0xE6)
compensation_params.dig_H4 = e4 << 4 | e5 & 0x0F
compensation_params.dig_H5 = ((e5 >> 4) & 0x0F) | (e6 << 4)
compensation_params.dig_H6 = read.signed_byte(0xE7)
return compensation_params
def test_signed_short():
smbus.read_word_data = MagicMock(return_value=0xCAFEBABE)
read = reader(bus=smbus, address=0x76)
assert read.signed_short(register=0x19A) == 0xBABE - 0x10000
smbus.read_word_data.assert_called_with(0x76, 0x19A)
def test_signed_byte():
smbus.read_byte_data = MagicMock(return_value=0xEE)
read = reader(bus=smbus, address=0x76)
assert read.signed_byte(register=0x19A) == 0xEE - 0x100
smbus.read_byte_data.assert_called_with(0x76, 0x19A)
def test_unsigned_short():
smbus.read_word_data = MagicMock(return_value=0xDEADBEEF)
read = reader(bus=smbus, address=0x76)
assert read.unsigned_short(register=0x19A) == 0xBEEF
smbus.read_word_data.assert_called_with(0x76, 0x19A)