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-rw-r--r--platforms/avr/sleep_led.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/platforms/avr/sleep_led.c b/platforms/avr/sleep_led.c
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+++ b/platforms/avr/sleep_led.c
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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"
+
+#ifndef SLEEP_LED_TIMER
+# define SLEEP_LED_TIMER 1
+#endif
+
+#if SLEEP_LED_TIMER == 1
+# define TCCRxB TCCR1B
+# define TIMERx_COMPA_vect TIMER1_COMPA_vect
+# if defined(__AVR_ATmega32A__) // This MCU has only one TIMSK register
+# define TIMSKx TIMSK
+# else
+# define TIMSKx TIMSK1
+# endif
+# define OCIExA OCIE1A
+# define OCRxx OCR1A
+#elif SLEEP_LED_TIMER == 3
+# define TCCRxB TCCR3B
+# define TIMERx_COMPA_vect TIMER3_COMPA_vect
+# define TIMSKx TIMSK3
+# define OCIExA OCIE3A
+# define OCRxx OCR3A
+#else
+error("Invalid SLEEP_LED_TIMER config")
+#endif
+
+/* 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)
+
+/** \brief Sleep LED initialization
+ *
+ * FIXME: needs doc
+ */
+void sleep_led_init(void) {
+ /* Timer1 setup */
+ /* CTC mode */
+ TCCRxB |= _BV(WGM12);
+ /* Clock selelct: clk/1 */
+ TCCRxB |= _BV(CS10);
+ /* Set TOP value */
+ uint8_t sreg = SREG;
+ cli();
+ OCRxx = SLEEP_LED_TIMER_TOP;
+ SREG = sreg;
+}
+
+/** \brief Sleep LED enable
+ *
+ * FIXME: needs doc
+ */
+void sleep_led_enable(void) {
+ /* Enable Compare Match Interrupt */
+ TIMSKx |= _BV(OCIExA);
+}
+
+/** \brief Sleep LED disable
+ *
+ * FIXME: needs doc
+ */
+void sleep_led_disable(void) {
+ /* Disable Compare Match Interrupt */
+ TIMSKx &= ~_BV(OCIExA);
+}
+
+/** \brief Sleep LED toggle
+ *
+ * FIXME: needs doc
+ */
+void sleep_led_toggle(void) {
+ /* Disable Compare Match Interrupt */
+ TIMSKx ^= _BV(OCIExA);
+}
+
+/** \brief Breathing Sleep LED brighness(PWM On period) table
+ *
+ * (64[steps] * 4[duration]) / 64[PWM periods/s] = 4 second breath cycle
+ *
+ * https://www.wolframalpha.com/input/?i=sin%28x%2F64*pi%29**8+*+255%2C+x%3D0+to+63
+ * (0..63).each {|x| p ((sin(x/64.0*PI)**8)*255).to_i }
+ */
+static 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};
+
+ISR(TIMERx_COMPA_vect) {
+ /* Software PWM
+ * timer:1111 1111 1111 1111
+ * \_____/\/ \_______/____ count(0-255)
+ * \ \______________ duration of step(4)
+ * \__________________ index of step table(0-63)
+ */
+ static union {
+ uint16_t row;
+ struct {
+ uint8_t count : 8;
+ uint8_t duration : 2;
+ uint8_t index : 6;
+ } 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);
+ }
+}