One of the modules in the Linux Industrial I/O Subsystem (IIO) is called am2315. It is used to drive I2C sensors for relative humidity and temperature - more specifically the devices known as AM2315 and Aosong AM2321.
While the I2C kernel space code for these devices is not too complicated to write and understand, setting up a working user space configuration for am2315 and the IIO subsystem until now has not been documented in one place and looks a bit tricky at first glance.
The content of this repo provides simple examples, demonstrating how to go about the setup task and how to read data conveyed by the am2315 module and IIO subsystem.
There are one or two shell scripts with basic comments (see the scripts directory) as examples how to set up/ tear down a working IIO configuration for am2315 and corresponding I2C devices.
The repo contains a very simple utility (catiio) for reading output (relative humidity, temperature and a timestamp) from the character device created by working setups for the AM2315 and AM2321 sensors.
The I2C address used for AM2315 and AM2321 devices is always 0x5c. Therefore there can never exist more than one of these devices per I2C adapter or bus.
catiio is essentially about decoding data types in channels
le:s16/16>>0 for in_humidityrelative_type
le:s16/16>>0 for in_temp_type
le:s64/64>>0 for in_timestamp_type
on the character device providing values from sensors.