Have you ever wanted more analog input pins on your Arduino project, but not wanted to fork out for a Mega? Or would you like to generate analogue signals? It solves both these problems as it has a single DAC (digital to analogue) converter as well as four ADCs (analogue to digital converters), all accessible via the I2C bus. If the I2C bus is new to you, please familiarise yourself with the readings here before moving forward.
This PCF8591 module operates on 3.3~5V,so can be used with an Arduino Due, Raspberry Pi or other 3.3 V development board. The DAC on the PCF8591 has a resolution of 8-bits, so it can generate a theoretical signal of between zero volts and the reference voltage (Vref) in 255 steps. There is also a temprature sensor and light sensor on the board so you get the current temp&light with this module.