60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
// Quick and dirty demo of how to get PWM on any pin with interrupts
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// ------- Preamble -------- //
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#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include "pinDefines.h"
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#define DELAY 3
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volatile uint8_t brightnessA;
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volatile uint8_t brightnessB;
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// -------- Functions --------- //
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static inline void initTimer0(void) {
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/* must be /64 or more for ISR timing */
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TCCR0B |= (1 << CS01) | (1 << CS00);
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/* both output compare interrupts */
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TIMSK0 |= ((1 << OCIE0A) | (1 << OCIE1B));
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TIMSK0 |= (1 << TOIE0); /* overflow interrupt enable */
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sei();
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}
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ISR(TIMER0_OVF_vect) {
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LED_PORT = 0xff;
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OCR0A = brightnessA;
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OCR0B = brightnessB;
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}
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ISR(TIMER0_COMPA_vect) {
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LED_PORT &= 0b11110000; /* turn off low four LEDs */
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}
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ISR(TIMER0_COMPB_vect) {
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LED_PORT &= 0b00001111; /* turn off high four LEDs */
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}
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int main(void) {
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// -------- Inits --------- //
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uint8_t i;
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LED_DDR = 0xff;
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initTimer0();
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// ------ Event loop ------ //
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while (1) {
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for (i = 0; i < 255; i++) {
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_delay_ms(DELAY);
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brightnessA = i;
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brightnessB = 255 - i;
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}
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for (i = 254; i > 0; i--) {
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_delay_ms(DELAY);
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brightnessA = i;
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brightnessB = 255 - i;
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}
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} /* End event loop */
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return 0; /* This line is never reached */
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}
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