I have a BME680 sensor interfaced using I2C to a Beaglebone Black SBC. It's functioning OK but I'm confused by what the 'gas heater' does.
I guess that the heater is to get the air quality measurements going but does it also affect the temperature and humidity readings?
I'm using the bme680 package from PyPi installed using pip.
Running this it goes into 'polling' mode and I see results like:-
13.79 C,967.85 hPa,66.97 %RH,71721.47698855039 Ohms
13.81 C,967.82 hPa,66.79 %RH,72968.57114389726 Ohms
13.84 C,967.82 hPa,66.63 %RH,74385.16382217684 Ohms
13.86 C,967.83 hPa,66.49 %RH,75403.50410127621 Ohms
13.88 C,967.83 hPa,66.33 %RH,77186.67437330067 Ohms
13.90 C,967.82 hPa,66.20 %RH,79198.32071358454 Ohms
13.93 C,967.81 hPa,66.05 %RH,79989.06250915483 Ohms
13.95 C,967.80 hPa,65.92 %RH,81618.88174279875 Ohms
13.97 C,967.80 hPa,65.80 %RH,82458.95418813737 Ohms
13.99 C,967.80 hPa,65.70 %RH,83712.21745256371 Ohms
14.01 C,967.81 hPa,65.60 %RH,84922.25079223014 Ohms
14.03 C,967.82 hPa,65.49 %RH,85999.60147520891 Ohms
14.05 C,967.84 hPa,65.39 %RH,87190.81907805824 Ohms
14.07 C,967.84 hPa,65.31 %RH,88326.88348620672 Ohms
14.09 C,967.84 hPa,65.21 %RH,89949.6685169239 Ohms
14.11 C,967.84 hPa,65.10 %RH,90411.07882563051 Ohms
14.13 C,967.85 hPa,65.03 %RH,91443.03457762799 Ohms
14.15 C,967.85 hPa,64.94 %RH,92305.04944738351 Ohms
14.16 C,967.85 hPa,64.86 %RH,95788.54299375357 Ohms
14.18 C,967.81 hPa,64.77 %RH,97001.04988745697 Ohms
14.20 C,967.82 hPa,64.69 %RH,98080.63309875103 Ohms
14.22 C,967.82 hPa,64.63 %RH,98906.22345883874 Ohms
14.23 C,967.82 hPa,64.56 %RH,100085.67844386413 Ohms
14.25 C,967.86 hPa,64.47 %RH,101997.027371513 Ohms
14.26 C,967.87 hPa,64.40 %RH,102950.26596207068 Ohms
14.28 C,967.85 hPa,64.33 %RH,103433.59820529057 Ohms
14.29 C,967.86 hPa,64.28 %RH,104167.16629089943 Ohms
It looks as if it's simply getting warmer and warmer, the temperature isn't really rising lake that, so what's going on?
I can't attach the python code I'm running so it's here.....
#!/usr/bin/env python3
import bme680
import time
print("""read-all.py - Displays temperature, pressure, humidity, and gas.
Press Ctrl+C to exit!
""")
try:
sensor = bme680.BME680(bme680.I2C_ADDR_PRIMARY)
except (RuntimeError, IOError):
sensor = bme680.BME680(bme680.I2C_ADDR_SECONDARY)
# These calibration data can safely be commented
# out, if desired.
print('Calibration data:')
for name in dir(sensor.calibration_data):
if not name.startswith('_'):
value = getattr(sensor.calibration_data, name)
if isinstance(value, int):
print('{}: {}'.format(name, value))
# 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)
sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)
print('\n\nInitial reading:')
for name in dir(sensor.data):
value = getattr(sensor.data, name)
if not name.startswith('_'):
print('{}: {}'.format(name, value))
sensor.set_gas_heater_temperature(320)
sensor.set_gas_heater_duration(150)
sensor.select_gas_heater_profile(0)
# Up to 10 heater profiles can be configured, each
# with their own temperature and duration.
# sensor.set_gas_heater_profile(200, 150, nb_profile=1)
# sensor.select_gas_heater_profile(1)
print('\n\nPolling:')
try:
while True:
if sensor.get_sensor_data():
output = '{0:.2f} C,{1:.2f} hPa,{2:.2f} %RH'.format(
sensor.data.temperature,
sensor.data.pressure,
sensor.data.humidity)
if sensor.data.heat_stable:
print('{0},{1} Ohms'.format(
output,
sensor.data.gas_resistance))
else:
print(output)
time.sleep(1)
except KeyboardInterrupt:
pass
