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4X4 Keypad Interfacing with ATmega16 and LCD Display

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Keypads are parts of HMI or Human Machine Interface and play really important role in a small embedded system where human interaction or human input is needed. Matrix keypads are well known for their simple architecture and ease of interfacing.

In this project, we will learn How to interface a 4X4 keypad with AVR ATmega16 microcontroller. Here, we will display the value of the pressed key in a 16X2 alphanumeric LCD. See the below table to know the value assigned to each key of the 4X4 keypad. For to display the value of the pressed key, the microcontroller should know if any key is pressed or not and if pressed then which key is pressed. To know all this, the microcontroller scans each row or column of the 4X4 keypad one by one continuously (scanning is done by the read_keypad function). When any key of 4X4 keypad is pressed, the read_keypad function returns the value of the pressed key and the microcontroller displays it in the 16X2 alphanumeric LCD. When none of the key is pressed the read_keypad function returns 0XFF and the LCD displays the value of the last pressed key. Now, press different keys of the 4×4 keypad and see the output in the 16×2 alphanumeric LCD.

Key Pressed	Key Value
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8
9	9
0	0
*	*
#	#
A	A
B	B
C	C
D	D

 

Softwares Required

• AVR Studio 4 Software
• WinAVR 2010 Software
• SinaProg Hex Downloader Software
• USBasp Driver

Hardwares Required

Name	Quantity
AVR Trainer Board-100 with ATmega16	1pc
AVR USB Programmer	1pc
12V, 1A DC SMPS Adaptor	1pc
RG1602A 16X2 Alphanumeric LCD Green	1pc
4X4 Keypad	1pc
1 to 1 Connector-Female to Female	3pc
10 to 10 FRC Female to Female Connector	3pc

Video

Connection Guide

The step-by-step connection guide for 4X4 Keypad Interfacing with ATmega16 and LCD Display is as follows