Hi, > Am 19.09.2017 um 08:01 schrieb Andreas Kemnade <[email protected]>: > > Hi, > > On Sat, 16 Sep 2017 21:57:32 +0200 > "H. Nikolaus Schaller" <[email protected]> wrote: > >> Hi, >> since we a re a tinkerphones community, I just had >> some fun with the GTA04A5 I want to share :) >> >> Maybe you know that there is a BME280 inside. It >> is a combined barometer, thermometer, hygrometer >> sensor chip. >> >> And it has full Letux kernel support so that it >> works out of the box. >> > Well, to produce nice input there still needs to be some logic, > Probably some power management logic. like suspend for some minutes to let the > gta04 cool down and read then the sensor directly after suspend.
That is easy: ./measure-suspend 300; cat /sys/bus/iio/devices/iio:device5/in_humidityrelative_input Or integrate it into a new script that does similar things as ./measure-suspend for suspend + wakeup by RTC. > > So the question is: does the hygrometer produce sane output when the gta04 > case > is closed? Yes, that would be nice if someone could find out. > >> It was simple to do some readout: >> >> cat /sys/bus/iio/devices/iio:device5/in_humidityrelative_input >> >> Here is the full sequence when breathing upon >> the sensor (of a board not installed in the case): >> >> root@letux:~# while true; do cat >> /sys/bus/iio/devices/iio:device5/in_humidityrelative_input; sleep 1; done >> 35.765625000 > root@letux:/sys/bus/iio/devices/iio:device1# cat in_temp_input > 39100 > root@letux:/sys/bus/iio/devices/iio:device1# cat in_humidityrelative_input > 78.563476562 > > Hmm, that does not make sense. 78% at 39 C. It was not in > my pocket. It is in a train. So why it is so humid? Hm. Maybe the sensor needs calibration? More likely it is too much influenced by the device temperature. Maybe printing temperature and humidity in a loop right after booting shows some drift/correlation? > >> Does this trigger new ideas for user interfaces? >> > humidity + pressure + temperature is nice for weather forecasts if > that are outdoor values. You can calculate the dewpoint. > The dewpoint is a good estimation of the temperature the next morning. > So you are not surprised too much if it becomes cold. > You can also estimate the lower cloud base with that. Nice ideas! > > That is the reason why I have a hih6130-family device with some flow of air > attached to my bicycle. BR, Nikolaus
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