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- #include <stdint.h>
- #include <avr/io.h>
- #include <avr/interrupt.h>
- #include <avr/pgmspace.h>
- #include "led.h"
- #include "sleep_led.h"
-
- /* Software PWM
- * ______ ______ __
- * | ON |___OFF___| ON |___OFF___| ....
- * |<-------------->|<-------------->|<- ....
- * PWM period PWM period
- *
- * 256 interrupts/period[resolution]
- * 64 periods/second[frequency]
- * 256*64 interrupts/second
- * F_CPU/(256*64) clocks/interrupt
- */
- #define SLEEP_LED_TIMER_TOP F_CPU/(256*64)
-
- void sleep_led_init(void)
- {
- /* Timer1 setup */
- /* CTC mode */
- TCCR1B |= _BV(WGM12);
- /* Clock selelct: clk/1 */
- TCCR1B |= _BV(CS10);
- /* Set TOP value */
- uint8_t sreg = SREG;
- cli();
- OCR1AH = (SLEEP_LED_TIMER_TOP>>8)&0xff;
- OCR1AL = SLEEP_LED_TIMER_TOP&0xff;
- SREG = sreg;
- }
-
- void sleep_led_enable(void)
- {
- /* Enable Compare Match Interrupt */
- TIMSK1 |= _BV(OCIE1A);
- }
-
- void sleep_led_disable(void)
- {
- /* Disable Compare Match Interrupt */
- TIMSK1 &= ~_BV(OCIE1A);
- }
-
-
- /* Breathing Sleep LED brighness(PWM On period) table
- * (32[steps] * 8[duration]) / 64[PWM periods/s] = 4 second breath cycle
- */
- static const uint8_t breathing_table[32] PROGMEM = {
- 0, 0, 0, 2, 9, 21, 37, 56, 78, 127, 151, 175, 197, 216, 232, 244,
- 254, 244, 216, 197, 175, 151, 127, 78, 56, 37, 21, 9, 2, 0, 0, 0
- };
-
- ISR(TIMER1_COMPA_vect)
- {
- /* Software PWM
- * timer:1111 1111 1111 1111
- * \----/\-/ \-------/+--- count(0-255)
- * | +--------------- duration of step(8)
- * +-------------------- index of step table(0-31)
- */
- static union {
- uint16_t row;
- struct {
- uint8_t count:8;
- uint8_t duration:3;
- uint8_t index:5;
- } pwm;
- } timer = { .row = 0 };
-
- timer.row++;
-
- // LED on
- if (timer.pwm.count == 0) {
- led_set(1<<USB_LED_CAPS_LOCK);
- }
- // LED off
- if (timer.pwm.count == pgm_read_byte(&breathing_table[timer.pwm.index])) {
- led_set(0);
- }
- }
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