Interfacing Array of LED’s with AVR Microcontroller (Atmega-8)

Aim:

Light Emitting Diodes (LED) is the most commonly used components, usually for displaying pins digital states. Typical uses of LEDs include alarm devices, timers and confirmation of user input such as a mouse click or keystroke. The main aim of this project is how to interface a array of LED’s to atmega-8 microcontroller.

Description:

Interfacing LED:

Fig. 1 shows how to interface the LED to microcontroller. As you can see the Cathode is connected through a resistor to GND & the Anode is connected to the Microcontroller pin. So when the Port Pin is HIGH the LED is ON & when the Port Pin is LOW the LED is turned OFF.

Interfacing LED with Atmega8

We now want to flash a LED in atmega8 board. It works by turning ON a LED & then turning it OFF & then looping back to START. However the operating speed of microcontroller is very high so the flashing frequency will also be very fast to be detected by human eye.

The atmega8 board has eight numbers of point LEDs, connected with I/O Port lines to make port pins high.

Pin Assignment with atmega8

	Point LEDs	Atmega 8  direction	Atmega 8 Lines	LED Selection	Connections
DIGITAL OUTPUTS	LED.0	DDRx=0x01	PORTx=0x01		Connect Any one PORT fromPORTB, PORTC, PORTD
	LED.1	DDRx=0x02	PORTx=0x02
	LED.2	DDRx=0x04	PORTx=0x04
	LED.3	DDRx=0x08	PORTx=0x08
	LED.4	DDRx=0x10	PORTx=0x10
	LED.5	DDRx=0x20	PORTx=0x20
	LED.6	DDRx=0x40	PORTx=0x40
	LED.7	DDRx=0x80	PORTx=0x80

Block Diagram

Schematic:

Code:

// *********************************************************
// Project: Interfacing Single LED to atmega8
// Author: Code Bloges
// Module description: Operate single LED
// *********************************************************

#define F_CPU 8000000UL
#include <avr/io.h>
#include<util/delay.h>

int main(void)
 {
     DDRB=0xff;
     while(1)
     {
         PORTB=0xff;
         _delay_ms(1000);
         PORTB=0x00;
         _delay_ms(1000);
     }
 }

Downloads:

The code was compiled in Atmel Studio 6 and simulation was made in Proteus v7.7.
To download code and proteus simulation click here.

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