avr_piano/main.c

/*
 *  EEL4746C - AVR Piano - Speaker Section
 *  speaker is connected to PD2 and ground
 *  buttons are connected to PB0-5, PC0-5, PD3-7
 *  the LCD Arduino UNO is connected to TX/RX (PD0/1)
 */

#include <avr/io.h>
#include <avr/interrupt.h>

#define F_CPU	16000000UL
#include <util/delay.h>

#define P_RX	0
#define P_TX	1
#define P_SPKR	2

unsigned short freqs[] = {
	100,
	200,
	250,
	300,
	350,
	400,
	500,
	600,
	700,
	750,
	1000,
	1250,
	1500,
	1750,
	2000,
	3000,
	4000,
	5000,
	6000,
	7000,
	8000
};
unsigned char note = 0;
unsigned char buttonpressed = 1;

int
main(void)
{
	DDRB = 0x00;
	DDRC = 0x00;
	DDRD = (1 << P_TX) | (1 << P_SPKR);

	PCMSK0 = 0xFF;
	PCMSK1 = 0xFF;
	PCMSK2 = ~(1 | (1 << 1) | (1 << 2));
	PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);

	sei();

	//for (;;);
	for (unsigned char n = 0;; n = (n + 1) % 2) {
		if (!buttonpressed) continue;
		_delay_us(71.43);
		PORTD ^= 1 << P_SPKR;
	}
}

ISR (PCINT0_vect)
{

}

ISR (PCINT1_vect)
{

}

ISR (PCINT2_vect)
{

}