An alphabetic keypad is similar to a numeric keypad, but it provides the complete set of alphabetical letters instead of numbers 0-9. This article presents a way to [[wysiwyg_imageupload::]]interface a keypad with 8051 microcontroller (AT89C51) to display alphabetical characters on an LCD module. Such kind of systems is commonly used in mobile phones to write an SMS and other texts. It can have further applications in displaying instant messages on other display systems such as LED matrices or other multi-segment displays. A 4x3 matrix keypad and a 16x2
LCD has been used here. Keypad and LCD are very commonly used input & output devices, respectively.
The connections in the circuit are as following: port P2 of microcontroller AT89C51 is used as data input port which is connected to data pins (7-14) of LCD. P3^0, P3^1 and P3^2 pins of microcontroller are connected to control pins RS, RW and EN of LCD. Port P0 is used to take input from keypad.