This is a simple program that queries Hygrochip humidity sensors from Linux. 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
Either the -d or -b option must be present
Usage: hyt-read [ -b I2C bus name | -d device file ] [ -a I2C slave address ]
[ -i seconds ] [ -T ] [ -H ]
Options:
-b X Open the I2C bus named X (e.g. bcm2708_i2c.1)
-d X Open the I2C device named X (e.g. /dev/i2c-0)
-a X Target I2C slave address X (default 0x28)
-i X Read data every X seconds
-T Print only temperature
-H Print only humidity
-h Show this message
$ ./hyt-read -d /dev/i2c-1
36.916317 27.065556
The first value returned is the relative humidity as a percentage, the second is the temperature in degrees C.
You can also specify use the I2C bus name (as reported by i2cdetect -l), i.e. on the Raspberry Pi revision 2:
./hyt-read -b bcm2708_i2c.1
The file munin_plugin.sh contains a script contributed by Florian
Heiderich to use this program with the munin monitoring tool.