mirror of
https://codeberg.org/eel4746_piano/avr_piano.git
synced 2024-11-22 01:00:29 -05:00
148 lines
2.6 KiB
C
148 lines
2.6 KiB
C
/*
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* EEL4746C - AVR Piano - Speaker Section
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* speaker is connected to PD2 and ground
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* 15 buttons are connected to PD3-7, PC0-4, PB0-4
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* the LCD Arduino UNO is connected to TX/RX (PD0/1)
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*/
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#define T1_PRESCALAR 8
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#define FREQ(f) (16e6 / f / T1_PRESCALAR / 2)
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#define HIGH(sn) ((sn >> 8) & 0xff)
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#define LOW(sn) (sn & 0xff)
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#define P_RX 0
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#define P_TX 1
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#define P_SPKR 2
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unsigned short freqs[] = {
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FREQ(100),
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FREQ(200),
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FREQ(250),
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FREQ(300),
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FREQ(350),
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FREQ(400),
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FREQ(500),
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FREQ(600),
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FREQ(700),
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FREQ(750),
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FREQ(1000),
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FREQ(1250),
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FREQ(1500),
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FREQ(1750),
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FREQ(2000),
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FREQ(3000),
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FREQ(4000),
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FREQ(5000),
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FREQ(6000),
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FREQ(7000),
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FREQ(8000),
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[255] = 0 // used as a 'silent' note
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};
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unsigned char note = 0;
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ISR (PCINT0_vect)
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{
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// check if any button in the whole port is pressed
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for (unsigned char i = 0; i <= 5; i++) {
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if (PINB & (1 << i)) {
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note = i + 5;
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break;
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}
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}
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}
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ISR (PCINT1_vect)
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{
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// check if any button in the whole port is pressed
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for (unsigned char i = 0; i <= 5; i++) {
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if (PINC & (1 << i)) {
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note = i + 5 + 6;
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break;
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}
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}
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}
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ISR (PCINT2_vect)
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{
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// check if any button in the whole port is pressed
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for (unsigned char i = 3; i <= 7; i++) {
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if (PIND & (1 << i)) {
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note = i - 3;
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break;
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}
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}
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}
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void
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usart_init(void)
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{
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// 115200 bps, RX/TX enabled
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UBRR0 = 8;
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UCSR0B = (1 << RXEN0) | (1 << TXEN0);
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UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
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}
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void
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usart_send(unsigned char c)
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{
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while (!(UCSR0A & (1 << UDRE0)));
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UDR0 = c;
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}
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unsigned char
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usart_read(void)
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{
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while (!(UCSR0A & (1 << RXC0)));
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return UDR0;
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}
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int
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main(void)
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{
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// Data Direction for Buttons, UART, Speaker
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DDRB = 0x00;
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DDRC = 0x00;
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DDRD = (1 << P_TX) | (1 << P_SPKR);
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// Enabling Pin Change Interrupt for All Buttons
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PCMSK0 = 0b00011111;
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PCMSK1 = 0b00011111;
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PCMSK2 = 0b11111000;
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PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);
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TCCR1A = 0x00; // use timer1 CTC mode
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TCCR1B = 1 << WGM12; // already prescaled by 8 in table
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sei();
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usart_init();
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// Sends Square wave to the Speaker When a Button is Pressed
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unsigned short cycles = 0;
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for (unsigned char n = 0;; n = (n + 1) % 2) {
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// check if any buttons are pressed, otherwise don't play a note
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if (((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0)
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continue;
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// Prepare Timer/Counter
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TCNT1 = 1;
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OCR1A = freqs[note];
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TCCR1B |= 1 << CS11;
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while ((TIFR1 & (1 << OCF1A)) == 0); // Monitor OutPut Compare Flag
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// Toggles port For Speaker
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PORTD ^= 1 << P_SPKR;
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TIFR1 |= 1 << OCF1A;
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TCCR1B &= ~(1 << CS11);
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cycles = (cycles + 1) % 0xffff;
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usart_send(HIGH(cycles));
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usart_send(LOW(cycles));
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}
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}
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