sleep_led.c
3341 bytes
1#include <stdint.h>
2#include <avr/io.h>
3#include <avr/interrupt.h>
4#include <avr/pgmspace.h>
5#include "led.h"
6#include "sleep_led.h"
7
8#ifndef SLEEP_LED_TIMER
9# define SLEEP_LED_TIMER 1
10#endif
11
12#if SLEEP_LED_TIMER == 1
13# define TCCRxB TCCR1B
14# define TIMERx_COMPA_vect TIMER1_COMPA_vect
15# if defined(__AVR_ATmega32A__) // This MCU has only one TIMSK register
16# define TIMSKx TIMSK
17# else
18# define TIMSKx TIMSK1
19# endif
20# define OCIExA OCIE1A
21# define OCRxx OCR1A
22#elif SLEEP_LED_TIMER == 3
23# define TCCRxB TCCR3B
24# define TIMERx_COMPA_vect TIMER3_COMPA_vect
25# define TIMSKx TIMSK3
26# define OCIExA OCIE3A
27# define OCRxx OCR3A
28#else
29error("Invalid SLEEP_LED_TIMER config")
30#endif
31
32/* Software PWM
33 * ______ ______ __
34 * | ON |___OFF___| ON |___OFF___| ....
35 * |<-------------->|<-------------->|<- ....
36 * PWM period PWM period
37 *
38 * 256 interrupts/period[resolution]
39 * 64 periods/second[frequency]
40 * 256*64 interrupts/second
41 * F_CPU/(256*64) clocks/interrupt
42 */
43#define SLEEP_LED_TIMER_TOP F_CPU / (256 * 64)
44
45/** \brief Sleep LED initialization
46 *
47 * FIXME: needs doc
48 */
49void sleep_led_init(void) {
50 /* Timer1 setup */
51 /* CTC mode */
52 TCCRxB |= _BV(WGM12);
53 /* Clock selelct: clk/1 */
54 TCCRxB |= _BV(CS10);
55 /* Set TOP value */
56 uint8_t sreg = SREG;
57 cli();
58 OCRxx = SLEEP_LED_TIMER_TOP;
59 SREG = sreg;
60}
61
62/** \brief Sleep LED enable
63 *
64 * FIXME: needs doc
65 */
66void sleep_led_enable(void) {
67 /* Enable Compare Match Interrupt */
68 TIMSKx |= _BV(OCIExA);
69}
70
71/** \brief Sleep LED disable
72 *
73 * FIXME: needs doc
74 */
75void sleep_led_disable(void) {
76 /* Disable Compare Match Interrupt */
77 TIMSKx &= ~_BV(OCIExA);
78}
79
80/** \brief Sleep LED toggle
81 *
82 * FIXME: needs doc
83 */
84void sleep_led_toggle(void) {
85 /* Disable Compare Match Interrupt */
86 TIMSKx ^= _BV(OCIExA);
87}
88
89/** \brief Breathing Sleep LED brighness(PWM On period) table
90 *
91 * (64[steps] * 4[duration]) / 64[PWM periods/s] = 4 second breath cycle
92 *
93 * https://www.wolframalpha.com/input/?i=sin%28x%2F64*pi%29**8+*+255%2C+x%3D0+to+63
94 * (0..63).each {|x| p ((sin(x/64.0*PI)**8)*255).to_i }
95 */
96static const uint8_t breathing_table[64] PROGMEM = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 4, 6, 10, 15, 23, 32, 44, 58, 74, 93, 113, 135, 157, 179, 199, 218, 233, 245, 252, 255, 252, 245, 233, 218, 199, 179, 157, 135, 113, 93, 74, 58, 44, 32, 23, 15, 10, 6, 4, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
97
98ISR(TIMERx_COMPA_vect) {
99 /* Software PWM
100 * timer:1111 1111 1111 1111
101 * \_____/\/ \_______/____ count(0-255)
102 * \ \______________ duration of step(4)
103 * \__________________ index of step table(0-63)
104 */
105 static union {
106 uint16_t row;
107 struct {
108 uint8_t count : 8;
109 uint8_t duration : 2;
110 uint8_t index : 6;
111 } pwm;
112 } timer = {.row = 0};
113 static led_t led_state = {0};
114
115 timer.row++;
116
117 // LED on
118 if (timer.pwm.count == 0) {
119 led_state.caps_lock = true;
120 led_set(led_state.raw);
121 }
122 // LED off
123 if (timer.pwm.count == pgm_read_byte(&breathing_table[timer.pwm.index])) {
124 led_state.caps_lock = false;
125 led_set(led_state.raw);
126 }
127}