Wiring 2N7000 AN10441 as Logic Level Converter for i2C Protocol Devices

Other micro-controller uses 5v as standard input voltage, many latest device modules, popular sensors, GPS, RF modules, Flash Memories, SPI storage, Display, use 3 to 3.3v  most of this devices requires logic level conversion to protect them from high voltage

Wiring the PCF8591 Digital to Analog Conversion with Microcontroller

This is the PCF8591 a single chip single supply, low power 8bit CMOS data acquisition device with four analog inputs. 1 analog output and i2c Serial communication bus interface that allows the connection to be connected in series integrated bus