Alphanumeric keypad with 8051(89c51,89c52) microcontroller

This tutorial teachs you how an alphanumeric keypad can be designed with 89c51 microcontroller, 16×2 lcd and 4×4 keypad? The main crux of the project lies in the code of the project. 4×4 keypad is just a cluster of buttons, arranged in coulomb and row orders. To use its buttons we have to write a software routine for each keypad button in our main code. Since buttons performed what they are programmed by us in the code. Hence we can take any function from the buttons. Usually we map them as the keypad keys printed on the physical keypad. In this tutorial we will map the keypad with multiple numbers and characters. A single button can enter multiple numbers or characters map to it.

The layout of alphanumeric keypad which i am going to program is below. In first 2 rows each button is assigned 3 characters and 1 number. Next row buttons are mapped to special characters and each button can enter 3 alphabets. Last row is assigned with mathematical operators and up to 2 mathematical operators can be entered by 1 button.

Alphanumeric key pad with microcontroller keys layout

Alphanumeric Keypad Hardware requirements

4×4 keypad
16×2 lcd
One 80s51 0r 89c51
Oscillator to provide necessary clock frequency to micro controller.
A potentiometer/variable resistor for setting 16×2 lcd contrast.

Alphanumeric keypad circuit diagram

4×4 keypad is connected to Port-1 of 8051(89c51,89c52) microcontroller. 16×2 lcd is connected to Port-2 of 89c51 microcontroller. 16×2 lcd controller controlling pins are connected to Port-3 of 8051 microcontroller. All the other connections are power connections for 8051 microcontroller. Aplly 5 volts to pin#31 and 40 of 8051 microcontroller. Insert 11.0592 MHz crystal between pins 18 and 19 of 8051 controller in parralel to two 33 pf capacitors. Connect your reset circuit to pin#9 of 89c51.

8051 Alphanumeric keypad circuit diagram

Alphanumeric keypad 8051 code

First of all never forget to include the #include<reg51.h> header file in every 8051 project because this is the file which contains all the necessary linking and debugging code in it for keil compiler. Next some functions and their definitions with working principle.

void keypad() Identifying pressed buttons.
void cmd(char c) Sending commands to the lcd.
void delay(int num) Necessary delay function.
void lcdinit() Initializing the lcd and its driver chip set.
void lcddata(char c) Sending data to lcd.

The statement sfr dataport=0xA0 is accessing Port-2 of 8051 with its sfr. Then coulomb and row pins are defined on Port-1 of 89c51. 16×2 lcd rw and en(To learn about rw and en click the link) pins are defined at Port-3 pin number 5 and 6.
Next comes my main function starts first with the lcdinit() function. It initializes the lcd 16×2 and its driver chip set. Ten i am printing the string “PLEASE ENTER YOUR NAME ” on my lcd after some time this message disappears and you can enter your name using 4×4 keypad.

Download the Project files and Code(C++,HEX). Code is written in C++ language and keil u-vision4 is used to compile the code and generate Hex code. Please give us your feed back on the project. If you have any queries, write them below.

Watch the project video below

Alphanumeric Keypad with 8051(89c51,89c52 code)