76 lines
1.3 KiB
C
76 lines
1.3 KiB
C
#include <avr/io.h>
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#include <util/delay.h>
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#define PIN_LED 0b1000
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#define PIN_BUTTON 0b0001
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#define PIN_TRIM 0b0001
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void init_ports(void) {
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// all outputs, swallows noise
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DDRB = 0xff;
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DDRC = 0xff;
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DDRD = 0xff;
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DDRD |= PIN_LED;
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PORTB |= PIN_BUTTON; // pull-up
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DDRB &= ~PIN_BUTTON;
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DDRC &= ~PIN_TRIM;
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}
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void init_pwm(void) {
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// page 84
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// 7-6: ouput A, 5-4: output B, 3-2: res, 1-0: waveform
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TCCR2A = 0b00100011;
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// 7-6: force output A/B, 5-4: res, 3: waveform, 2-0: clock source
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TCCR2B = 0b01000001;
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// duty
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OCR2B = 0;
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}
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void deinit_pwm(void) {
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TCCR2A = 0;
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TCCR2B = 0;
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OCR2B = 0;
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}
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void pwm_fade_in(int until, int step) {
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int i;
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for (i = 0; i < until; i += step) {
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OCR2B = i;
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_delay_ms(0.5);
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}
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}
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void pwm_fade_out(int until, int step) {
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int i;
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for (i = OCR2B; i > until; i -= step) {
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OCR2B = i;
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_delay_ms(0.25);
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}
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}
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/*
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int analog_read(void) {
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ADCSRA |= ADEN;
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ADCSRA |= ADSC;
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}*/
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int main(void) {
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init_ports();
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while (1) {
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if (!(PINB & PIN_BUTTON)) {
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init_pwm();
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pwm_fade_in(0x7f >> 5, 1);
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_delay_ms(300);
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OCR2B = 0x7f >> 3;
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_delay_ms(150);
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pwm_fade_out(32, 4);
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_delay_ms(50);
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pwm_fade_out(0, 4);
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}
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deinit_pwm();
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PORTD &= ~PIN_LED;
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}
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return 0;
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}
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