The Raspberry does not have analog inputs in contrast in contrast to the Arduino or rather it is not an ADC (analog digital converter) integrated in the Raspberry Pi. This limits the Raspberry Pi if you want to use sensors by which the values are not issued digital. You can solve this problem with this analog digital converter.
This module has a 16 bit precise ADC which you can use with the Raspberryto expand the the single-board computer to 4 analog inputs. It will be connected via I2C to the Raspberry Pi and incurs the analog measurement and issues the values to the Raspberry Pi.
To get more information for this module, please use the link ("further information") under Downloads.
Analog Digital Converter ADS1115
2,0 - 5,5 V
Programmable Data Rate
8 - 860 sps
18 x 28 mm