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			96 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			96 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| #include <stdint.h>
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| #include <avr/io.h>
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| #include <avr/interrupt.h>
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| #include <avr/pgmspace.h>
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| #include "led.h"
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| #include "sleep_led.h"
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| 
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| /* Software PWM
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|  *  ______           ______           __
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|  * |  ON  |___OFF___|  ON  |___OFF___|   ....
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|  * |<-------------->|<-------------->|<- ....
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|  *     PWM period       PWM period
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|  *
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|  * 256              interrupts/period[resolution]
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|  * 64               periods/second[frequency]
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|  * 256*64           interrupts/second
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|  * F_CPU/(256*64)   clocks/interrupt
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|  */
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| #define SLEEP_LED_TIMER_TOP F_CPU/(256*64)
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| 
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| void sleep_led_init(void)
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| {
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|     /* Timer1 setup */
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|     /* CTC mode */
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|     TCCR1B |= _BV(WGM12);
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|     /* Clock selelct: clk/1 */
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|     TCCR1B |= _BV(CS10);
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|     /* Set TOP value */
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|     uint8_t sreg = SREG;
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|     cli();
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|     OCR1AH = (SLEEP_LED_TIMER_TOP>>8)&0xff;
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|     OCR1AL = SLEEP_LED_TIMER_TOP&0xff;
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|     SREG = sreg;
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| }
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| 
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| void sleep_led_enable(void)
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| {
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|     /* Enable Compare Match Interrupt */
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|     TIMSK1 |= _BV(OCIE1A);
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| }
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| 
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| void sleep_led_disable(void)
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| {
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|     /* Disable Compare Match Interrupt */
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|     TIMSK1 &= ~_BV(OCIE1A);
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| }
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| 
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| void sleep_led_toggle(void)
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| {
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|     /* Disable Compare Match Interrupt */
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|     TIMSK1 ^= _BV(OCIE1A);
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| }
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| 
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| 
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| /* Breathing Sleep LED brighness(PWM On period) table
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|  * (64[steps] * 4[duration]) / 64[PWM periods/s] = 4 second breath cycle
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|  *
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|  * http://www.wolframalpha.com/input/?i=%28sin%28+x%2F64*pi%29**8+*+255%2C+x%3D0+to+63
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|  * (0..63).each {|x| p ((sin(x/64.0*PI)**8)*255).to_i }
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|  */
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| static const uint8_t breathing_table[64] PROGMEM = {
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| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 4, 6, 10,
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| 15, 23, 32, 44, 58, 74, 93, 113, 135, 157, 179, 199, 218, 233, 245, 252,
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| 255, 252, 245, 233, 218, 199, 179, 157, 135, 113, 93, 74, 58, 44, 32, 23,
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| 15, 10, 6, 4, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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| };
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| 
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| ISR(TIMER1_COMPA_vect)
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| {
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|     /* Software PWM
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|      * timer:1111 1111 1111 1111
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|      *       \_____/\/ \_______/____  count(0-255)
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|      *          \    \______________  duration of step(4)
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|      *           \__________________  index of step table(0-63)
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|      */
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|     static union {
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|         uint16_t row;
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|         struct {
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|             uint8_t count:8;
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|             uint8_t duration:2;
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|             uint8_t index:6;
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|         } pwm;
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|     } timer = { .row = 0 };
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| 
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|     timer.row++;
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|     
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|     // LED on
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|     if (timer.pwm.count == 0) {
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|         led_set(1<<USB_LED_CAPS_LOCK);
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|     }
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|     // LED off
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|     if (timer.pwm.count == pgm_read_byte(&breathing_table[timer.pwm.index])) {
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|         led_set(0);
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|     }
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| }
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