control7 blog

This small tutorial will show how to read signal from a push button and on/off two led by the input signal. I have used Atmega48 to write and test the program but you can use any AVR which supports AVR GCC.

Before pressing the push button it is like:

After pressing the push button:

Sketch of the schematic:

Here is the program:

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#include <avr/io.h>
#include <stdio.h>
 
//Method to read pin status
uint8_t GetKeyStatus(uint8_t key)
{
	return (!(PINB & (1<<key)));
}
 
void main()
{
	DDRB = 0b00000111; //set B0, B1 and B2 as output
	while(1)
	{
		if(GetKeyStatus(0)) //reading B0 status
		{
			PORTB = 0b00000010; //set B1 as HIGH
		}
		else
		{
			PORTB = 0b00000100;	//set B2 as HIGH
		}
	}
}

We can read PB0. When the button is not pressed, PB1 is high otherwise PB2 is high.

Tags: AVR, AVR GCC, I/O, Input, LED, Output, Push Button