This is a simple program that queries Hygrochip humidity sensors from Linux, particularly from the Raspberry Pi. It was developed and tested with the HYT-271, but it should work with the other models that use the same sample code. See my blog post for more details.
To build, just do:
$ make
And then to run it:
$ ./hyt-read
50.582920 21.314777
The first value returned is the relative humidity as a percentage, the second is the temperature in degrees C.
By default, it uses the I2C bus name that is correct for the IO header pins on the Raspberry Pi revision 2. You can supply an alternative bus name, e.g.
./hyt-read bcm2708_i2c.0
The file munin_plugin.sh contains a script contributed by Florian
Heiderich to use this program with the munin monitoring tool.