In this tutorial we will look at how to read the status of a switch and control the led depending on the switch status. Refer the AVR I/O Register Configuration tutorial for basics of GPIO register configuration.

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Basic

Starter AVR has ATmega32 micro controller and has two LED's and two user switches on board. we'll use the same for this example so no extra hardware is required. I am using switch connected to PD3 and LED connected to PD5. Dump the code and press the SW2 on board, you will find that LED2 will change state according to the switch status.

Hookup

Code

	#include <avr/io.h>

	#define LED 5
	#define SWITCH 3

	int main(void)
	{

	DDRD \|= (1<<LED); // Configure PD5 as output to connect Led
	DDRD &= ~(1<<SWITCH); // Configure PD3 as input to connect switch
	PORTD = 0x08; // Enable The PullUps of PORTC.
	while(1)
	{

	while(((PIND)&(1<<SWITCH))==0u) // Read the switch status and display it on Led
	{
	PORTD \|= (1<<LED);
	}
	PORTD &= ~(1<<LED);
	}
	return 0;
	}