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/*
* EEL4746C - AVR Piano - Speaker Section
* speaker is connected to PD2 and ground, PD3-7
* the LCD Arduino UNO is connected to TX/RX (PD0/1)
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#define T1_PRESCALAR 8
#define FREQ(f) (16e6 / f / T1_PRESCALAR / 2)
#define P_RX 0
#define P_TX 1
#define P_SPKR 2
unsigned short freqs[] = {
FREQ(100),
FREQ(200),
FREQ(250),
FREQ(300),
FREQ(350),
FREQ(400),
FREQ(500),
FREQ(600),
FREQ(700),
FREQ(750),
FREQ(1000),
FREQ(1250),
FREQ(1500),
FREQ(1750),
FREQ(2000),
FREQ(3000),
FREQ(4000),
FREQ(5000),
FREQ(6000),
FREQ(7000),
FREQ(8000),
};
unsigned char note = 8;
unsigned char buttonpressed = 1;
int
main(void)
{
// Data Direction for Buttons, UART, Speaker
DDRB = 0x00;
DDRC = 0x00;
DDRD = (1 << P_TX) | (1 << P_SPKR);
// Enabling Pin Change Interrupt for All Buttons
PCMSK0 = 0xFF;
PCMSK1 = 0xFF;
PCMSK2 = ~(1 | (1 << 1) | (1 << 2));
PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);
TCCR1A = 0x00; // use timer1 CTC mode
TCCR1B = 1 << WGM12; // already prescaled by 8 in table
sei();
// Sends Square wave to the Speaker When a Button is Pressed
for (unsigned char n = 0;; n = (n + 1) % 2) {
if (!buttonpressed && n == 0) continue;
// Prepare Timer/Counter
TCNT1 = 1;
OCR1A = freqs[note];
TCCR1B |= 1 << CS11;
while ((TIFR1 & (1 << OCF1A)) == 0); // Monitor OutPut Compare Flag
// Toggles port For Speaker
PORTD ^= 1 << P_SPKR;
TIFR1 |= 1 << OCF1A;
TCCR1B &= ~(1 << CS11);
}
}
ISR (PCINT0_vect)
{
}
ISR (PCINT1_vect)
{
}
ISR (PCINT2_vect)
{
}
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