Introduction LCD is the most common display devices used in different dedicated applications be it the instrumentation, medical equipment, panels, robotics etc. It is quite easy to interface it with the microprocessors or microcontrollers. We can directly interface a LCD with microcontrollers, however, for interfacing with microprocessors, we need a peripheral device such as 8255. Here in this post we discuss the basics of LCD, its commands, interfacing using 8255 PPI an final a program to initialize LCD to display some user data on it. PIN Diagram of LCD Pin number Symbol I/O Description 1 Vss xx GND 2 Vcc xx +5V 3 VEE Xx Power Supply to control contrats (use POT) 4 RS I RS=0 to select command Register, to allow user to send command to LCD RS=1 to select data register, allowing user to send data for display 5 R/W I R/W=0 : to Write R/W=1: to