This article explores the TWI interfacing between two ATmega32 controllers. Readers are advised to go through TWI Communication and TWI registers[[wysiwyg_imageupload::]]of ATmega32 before going further. Generally modes 1 & 3 and modes 2 & 4 are used together. This article explains the use of these four modes by an experiment.To establish the communication between two ATmega32 using TWI interface. First the Master starts by sending data then the slave transmits complement of the received data to the master. When the Master receives the complemented data, it shifts the original data to left. This process of transmitting and receiving continues. As the data value reaches 0x80 the whole process is repeated. At the starting, value of the original data is 0x01. The received value is displayed on PORTB at both the ends.