81 lines
1.6 KiB
C
81 lines
1.6 KiB
C
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#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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uint16_t freq_high = 1200;
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uint16_t freq_low = 800;
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volatile uint8_t speed = 25;
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volatile uint8_t tick_count = 0;
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volatile uint16_t beep_time = 0;
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volatile int debounce_int2 = 10;
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volatile int debounce_int3 = 10;
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volatile int tick_timer_start = 0xffff;
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void start_timer() {
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TCCR1B |= _BV(CS10) | _BV(CS12); // clk/1024
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TIMSK1 |= _BV(TOIE1);
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TCCR4B |= _BV(CS41); // clk/8
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TIMSK4 |= _BV(OCIE4A);
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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(INT2_vect) {
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if (debounce_int2) return;
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debounce_int2 = 100;
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if (speed < 100) speed++;
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}
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ISR(INT3_vect) {
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if (debounce_int3) return;
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debounce_int3 = 100;
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if (speed > 1) speed--;
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}
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ISR(TIMER1_OVF_vect) {
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tick_count++;
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if (tick_count > 3) tick_count = 0;
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beep_time = 50;
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TCNT1 = tick_timer_start;
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}
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ISR(TIMER4_COMPA_vect) {
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if (beep_time > 0) {
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PORTK ^= 0b10000000;
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beep_time--;
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}
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TCNT4 = 0;
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}
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void main() {
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DDRK = 0b10000000;
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DDRD = 0b00000000;
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PORTD |= 0b00001100;
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// EIMSK controls which ports can trigger interrupts
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EIMSK |= _BV(INT2) | _BV(INT3);
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// Trigger on falling edge on INT2 and INT3
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EICRA |= _BV(ISC21) | _BV(ISC31);
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start_timer();
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while (true) {
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OCR4A = (F_CPU / 8) / (tick_count == 0 ? freq_high : freq_low);
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tick_timer_start = 0xffff - (F_CPU / 1024 / 1000) * (100 + speed * 10);
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if (debounce_int2 > 0) debounce_int2--;
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if (debounce_int3 > 0) debounce_int3--;
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_delay_ms(1);
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}
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}
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