WAP for keypad and LCD interfacing

Program for keypad and LCD interfacing

Keyboard is one of the most widely used input device of micro controller.

Keypad is used to take input from the user for further processing.

The main matrix keyboard is made up by arranging push buttons, switches in rows and columns.

In the straight way to connect a 4*4  keypad to a micro controller we need 16 input pins.

In case of matrix keypad both the end of switches are connected to the point pin.

An LCD communicated with the host (89851) via the data bus (D0-D7) and 3 central lines Enable(EN) Register select(RS) is low and Read/Write LCD contains two byte with registers.

The matrix keypad is made up by arranging push buttons, switches in rows and columns.

In the straight way to connect a 4*4 keypad to a micro controller we need 16 input pins.

In case of matrix keypad both the ends of switches are controlled to the point pin.

An LCD communicated with the host(89851) via the data bus (D0-D7) and 3 control lines enables (EN).

Register select (RS) is low and Read/Write LCD contains two byte wide registers.

Instruction Register (IR))  or command Register for sending commands , accesed when RS is pulled low.

Data Register (DR) : For sending characters to be displayed  accessed when RS is made high.

LCD can be programmed to display characters in various attributes such as character resolution whether 5*7 dots/character or 5*10 dots/characters type of cursor.