106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
#define __AVR_ATmega2560__
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#define F_CPU 16000000UL
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#include <avr/io.h>
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#include <util/delay.h>
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#include <stdbool.h>
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#include <avr/interrupt.h>
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volatile uint16_t tick_timer_start = 0xffff - (F_CPU / 1024 / 1000);
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volatile bool speaker_disabled = true;
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uint16_t notes[][3] = {
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{ 1000, 200, 30 },
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{ 1200, 200, 30 },
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{ 1500, 200, 30 },
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{ 1600, 200, 30 },
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{ 1500, 200, 30 },
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{ 1200, 100, 10 },
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{ 1000, 300, 100 },
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};
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void ADC_Setup() {
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// AVCC with external capacitor at AREF pin
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ADMUX = _BV(REFS0);
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// Enable ADC, set prescaler to 8tick_timer_start
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ADCSRA = _BV(ADEN) | _BV(ADPS0) | _BV(ADPS1);
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// Perform dummy readout
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ADCSRA |= _BV(ADSC); // Start conversion
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while (ADCSRA & _BV(ADSC)); // Await result
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(void) ADCW; // Read out result
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}
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uint16_t ADC_Read(uint8_t channel) {
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// Select chosen channel
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ADMUX = (ADMUX & ~(0x1F)) | (channel & 0x1F);
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// Start conversion
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ADCSRA |= _BV(ADSC);
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// Await the result
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while (ADCSRA & _BV(ADSC));
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// Although it doesn't appear to be documented, ADCW holds the covnersion result
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return ADCW;
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}
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uint16_t ADC_Read_Avg(uint8_t channel, uint8_t samples) {
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uint32_t sum = 0;
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for (int i = 0; i < samples; i++) {
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sum += ADC_Read(channel);
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}
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return (uint16_t)(sum / samples);
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}
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void TIMER_Setup() {
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TCCR1B |= _BV(CS10) | _BV(CS12); // clk/1024
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// Set the TOIE (Timer Overflow Interrupt Enable) bit
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// on TIMSK1 (Timer 1 Interrupt Mask Register).
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TIMSK1 |= _BV(TOIE1);
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// Sets the current timer value
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TCNT1 = tick_timer_start;
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// Enable interrupts
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sei();
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}
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// ISR is used to handle interrupts. TIMER1_OVF_vect
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// is triggered whenever timer 1 (16 bit) overflows.
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ISR(TIMER1_OVF_vect) {
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TCNT1 = tick_timer_start;
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PORTB ^= 0b10000000;
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if (speaker_disabled) PORTK &= 0b11111110;
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else PORTK ^= 0b00000001;
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}
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void play_note(uint16_t freq, uint8_t delay, uint8_t delay_silence) {
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speaker_disabled = false;
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tick_timer_start = 0xffff - (F_CPU / freq / 1000);
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for (int i = 0; i < delay; i++) _delay_ms(1);
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speaker_disabled = true;
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for (int i = 0; i < delay_silence; i++) _delay_ms(1);
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}
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void main() {
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DDRK = 0b00000001;
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PORTB = 0b10000000; // Start with LED enabled
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ADC_Setup();
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TIMER_Setup();
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long rows = sizeof(notes) / sizeof(notes[0]);
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while (true) {
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for (int i = 0; i < rows; i++) {
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play_note(notes[i][0], notes[i][1], notes[i][2]);
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}
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//uint16_t value = ADC_Read_Avg(0, 4);
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//speaker_disabled = value == 0;
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//if (value < 100) value = 100; // Anything lower than this causes issues
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//tick_timer_start = 0xffff - (F_CPU / value / 1000);
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}
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}
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