The AD7705 is a two channel sigma delta converter which has differential inputs, a PGA and programmable data rates. It's perfect for slowly changing inputs such as pressure, temperature, heart rate etc.
This repo offers the class AD7705Comm which does all the low level
communications with the AD7705. The user just need to register a
callback handler which then returns the samples in realtime.
The class uses the DRDY of the AD7705 connected to Port 22 and waits for a falling edge on this port to read the data. This is done via interrupts / poll so that the ADC process sleeps until new data becomes available.