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4X4 Keypad Interfacing with ATmega32 and LED 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 ATmega32 microcontroller. Here, we will display the value of the pressed key in a 1X8 LED array. 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 1X8 LED array. When none of the key is pressed the read_keypad function returns 0XFF and the 1X8 LED array displays the value of the last pressed key. Now, press different keys of the 4×4 keypad and see the output in the 1X8 LED array.

Key Pressed

Key Value

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

9

0

0

*

10

#

11

A

12

B

13

C

14

D

15

 

Softwares Required

Hardwares Required

Name Quantity
AVR Trainer Board-100 with ATmega32 1pc
AVR USB Programmer 1pc
12V, 1A DC SMPS Adaptor 1pc
4X4 Keypad 1pc
10 to 10 FRC Female to Female Connector 3pc

Circuit Diagram

Video

Connection Guide

The step-by-step connection guide for 4X4 Keypad Interfacing with ATmega32 and LED Display is as follows

  • Steps - 1 ( 0f 7 )

    Insert the DC Pin of 12V, 1A DC Adapter to the DC Socket of AVR Trainer Board-100.

  • Steps - 2 ( 0f 7 )

    Connect PortB header with LED header in AVR Trainer Board-100 with a 10 to 10 FRC Female Connector.

  • Steps - 3 ( 0f 7 )

    Connect the 4X4 Keypad header of 4X4 Keypad with PortC header of AVR Trainer Board-100 with a 10 to 10 FRC Female Connector.

  • Steps - 4 ( 0f 7 )

    Connect the ISP header of AVR Trainer Board-100 with AVR USB Programmer header of AVR USB Programmer with a 10 to 10 FRC Female Connector.

  • Steps - 5 ( 0f 7 )

    Connect the AVR USB Programmer to the PC/Laptop's USB Port directly or with the help of USB AM-FM Cable.

  • Steps - 6 ( 0f 7 )

    Switch on the power with the help of Power Switch of AVR Trainer Board-100.

  • Steps - 7 ( 0f 7 )

    Download the 4X4 Keypad Interfacing with ATmega32 and LED Display Hex file to AVR Trainer Board-100 with the help of SinaProg Hex downloader and AVR USB Programmer.

  • Insert the DC Pin of 12V, 1A DC Adapter to the DC Socket of AVR Trainer Board-100.

    Steps - 1 ( 0f 7 )

  • Connect PortB header with LED header in AVR Trainer Board-100 with a 10 to 10 FRC Female Connector.

    Steps - 2 ( 0f 7 )

  • Connect the 4X4 Keypad header of 4X4 Keypad with PortC header of AVR Trainer Board-100 with a 10 to 10 FRC Female Connector.

    Steps - 3 ( 0f 7 )

  • Connect the ISP header of AVR Trainer Board-100 with AVR USB Programmer header of AVR USB Programmer with a 10 to 10 FRC Female Connector.

    Steps - 4 ( 0f 7 )

  • Connect the AVR USB Programmer to the PC/Laptop's USB Port directly or with the help of USB AM-FM Cable.

    Steps - 5 ( 0f 7 )

  • Switch on the power with the help of Power Switch of AVR Trainer Board-100.

    Steps - 6 ( 0f 7 )

  • Download the 4X4 Keypad Interfacing with ATmega32 and LED Display Hex file to AVR Trainer Board-100 with the help of SinaProg Hex downloader and AVR USB Programmer.

    Steps - 7 ( 0f 7 )

Downloads

4x4 Keypad Interfacing with ATmega32 and LED Display Project File
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