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added set_temp_offset function and example

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This commit is contained in:
Lars Lühr 2018-05-28 21:18:20 +00:00
parent 40b4b63b93
commit 1c9ba41306
2 changed files with 61 additions and 2 deletions
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46
examples/temp-offset.py Normal file
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@ -0,0 +1,46 @@
#!/usr/bin/env python
import bme680
print("""Display Temperature, Pressure and Humidity with different offsets.
""")
sensor = bme680.BME680()
# These oversampling settings can be tweaked to
# change the balance between accuracy and noise in
# the data.
sensor.set_humidity_oversample(bme680.OS_2X)
sensor.set_pressure_oversample(bme680.OS_4X)
sensor.set_temperature_oversample(bme680.OS_8X)
sensor.set_filter(bme680.FILTER_SIZE_3)
print("Initial readings")
sensor.get_sensor_data()
output = "{0:.2f} C,{1:.2f} hPa,{2:.3f} %RH".format(sensor.data.temperature, sensor.data.pressure, sensor.data.humidity)
print(output)
print("SET offset 4 degrees celsius")
sensor.set_temp_offset(4)
sensor.get_sensor_data()
output = "{0:.2f} C,{1:.2f} hPa,{2:.3f} %RH".format(sensor.data.temperature, sensor.data.pressure, sensor.data.humidity)
print(output)
print("SET offset -10 degrees celsius")
sensor.set_temp_offset(-10)
sensor.get_sensor_data()
output = "{0:.2f} C,{1:.2f} hPa,{2:.3f} %RH".format(sensor.data.temperature, sensor.data.pressure, sensor.data.humidity)
print(output)
print("SET offset -100 degrees celsius")
sensor.set_temp_offset(-100)
sensor.get_sensor_data()
output = "{0:.2f} C,{1:.2f} hPa,{2:.3f} %RH".format(sensor.data.temperature, sensor.data.pressure, sensor.data.humidity)
print(output)
print("SET offset 0 degrees celsius")
sensor.set_temp_offset(0)
sensor.get_sensor_data()
output = "{0:.2f} C,{1:.2f} hPa,{2:.3f} %RH".format(sensor.data.temperature, sensor.data.pressure, sensor.data.humidity)
print(output)

17
library/bme680/__init__.py
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@ -36,7 +36,7 @@ class BME680(BME680Data):
self.set_temperature_oversample(OS_8X)
self.set_filter(FILTER_SIZE_3)
self.set_gas_status(ENABLE_GAS_MEAS)
self.set_temp_offset(0)
self.get_sensor_data()
def _get_calibration_data(self):
@ -56,6 +56,19 @@ class BME680(BME680Data):
self._set_regs(SOFT_RESET_ADDR, SOFT_RESET_CMD)
time.sleep(RESET_PERIOD / 1000.0)
def set_temp_offset(self, value):
"""Set temperature offset in celsius
If set, the temperature t_fine will be increased by given value in celsius.
:param value: Temperature offset in Celsius, eg. 4, -8
"""
if value == 0:
self.offset_temp_in_t_fine = 0
elif value < 0:
self.offset_temp_in_t_fine = -int((((abs(value) * 100) << 8) - 128) / 5)
else:
self.offset_temp_in_t_fine = int((((abs(value) * 100) << 8) - 128) / 5)
def set_humidity_oversample(self, value):
"""Set humidity oversampling
@ -293,7 +306,7 @@ class BME680(BME680Data):
var3 = ((var3) * (self.calibration_data.par_t3 << 4)) >> 14
# Save teperature data for pressure calculations
self.calibration_data.t_fine = (var2 + var3)
self.calibration_data.t_fine = (var2 + var3) + self.offset_temp_in_t_fine
calc_temp = (((self.calibration_data.t_fine * 5) + 128) >> 8)
return calc_temp