328 lines
11 KiB
C
328 lines
11 KiB
C
#include "backlight.h"
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#include "gpio.h"
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#include "progmem.h"
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#include <avr/io.h>
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#include <avr/interrupt.h>
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// Maximum duty cycle limit
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#ifndef BACKLIGHT_LIMIT_VAL
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# define BACKLIGHT_LIMIT_VAL 255
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#endif
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#if (defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__) || defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)) && (BACKLIGHT_PIN == B5 || BACKLIGHT_PIN == B6 || BACKLIGHT_PIN == B7)
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# define ICRx ICR1
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# define TCCRxA TCCR1A
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# define TCCRxB TCCR1B
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# define TIMERx_OVF_vect TIMER1_OVF_vect
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# define TIMSKx TIMSK1
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# define TOIEx TOIE1
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# if BACKLIGHT_PIN == B5
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# define COMxx0 COM1A0
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# define COMxx1 COM1A1
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# define OCRxx OCR1A
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# elif BACKLIGHT_PIN == B6
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# define COMxx0 COM1B0
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# define COMxx1 COM1B1
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# define OCRxx OCR1B
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# elif BACKLIGHT_PIN == B7
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# define COMxx0 COM1C0
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# define COMxx1 COM1C1
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# define OCRxx OCR1C
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# endif
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#elif (defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__) || defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)) && (BACKLIGHT_PIN == C4 || BACKLIGHT_PIN == C5 || BACKLIGHT_PIN == C6)
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# define ICRx ICR3
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# define TCCRxA TCCR3A
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# define TCCRxB TCCR3B
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# define TIMERx_OVF_vect TIMER3_OVF_vect
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# define TIMSKx TIMSK3
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# define TOIEx TOIE3
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# if BACKLIGHT_PIN == C4
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# if (defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__))
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# error This MCU has no C4 pin!
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# else
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# define COMxx0 COM3C0
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# define COMxx1 COM3C1
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# define OCRxx OCR3C
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# endif
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# elif BACKLIGHT_PIN == C5
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# if (defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__))
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# error This MCU has no C5 pin!
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# else
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# define COMxx0 COM3B0
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# define COMxx1 COM3B1
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# define OCRxx OCR3B
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# endif
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# elif BACKLIGHT_PIN == C6
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# define COMxx0 COM3A0
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# define COMxx1 COM3A1
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# define OCRxx OCR3A
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# endif
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#elif (defined(__AVR_AT90USB162__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega32U2__)) && (BACKLIGHT_PIN == B7 || BACKLIGHT_PIN == C5 || BACKLIGHT_PIN == C6)
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# define ICRx ICR1
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# define TCCRxA TCCR1A
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# define TCCRxB TCCR1B
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# define TIMERx_OVF_vect TIMER1_OVF_vect
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# define TIMSKx TIMSK1
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# define TOIEx TOIE1
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# if BACKLIGHT_PIN == B7
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# define COMxx0 COM1C0
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# define COMxx1 COM1C1
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# define OCRxx OCR1C
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# elif BACKLIGHT_PIN == C5
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# define COMxx0 COM1B0
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# define COMxx1 COM1B1
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# define OCRxx OCR1B
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# elif BACKLIGHT_PIN == C6
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# define COMxx0 COM1A0
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# define COMxx1 COM1A1
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# define OCRxx OCR1A
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# endif
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#elif defined(__AVR_ATmega32A__) && (BACKLIGHT_PIN == D4 || BACKLIGHT_PIN == D5)
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# define ICRx ICR1
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# define TCCRxA TCCR1A
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# define TCCRxB TCCR1B
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# define TIMERx_OVF_vect TIMER1_OVF_vect
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# define TIMSKx TIMSK
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# define TOIEx TOIE1
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# if BACKLIGHT_PIN == D4
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# define COMxx0 COM1B0
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# define COMxx1 COM1B1
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# define OCRxx OCR1B
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# elif BACKLIGHT_PIN == D5
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# define COMxx0 COM1A0
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# define COMxx1 COM1A1
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# define OCRxx OCR1A
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# endif
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#elif (defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)) && (BACKLIGHT_PIN == B1 || BACKLIGHT_PIN == B2)
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# define ICRx ICR1
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# define TCCRxA TCCR1A
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# define TCCRxB TCCR1B
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# define TIMERx_OVF_vect TIMER1_OVF_vect
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# define TIMSKx TIMSK1
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# define TOIEx TOIE1
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# if BACKLIGHT_PIN == B1
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# define COMxx0 COM1A0
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# define COMxx1 COM1A1
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# define OCRxx OCR1A
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# elif BACKLIGHT_PIN == B2
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# define COMxx0 COM1B0
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# define COMxx1 COM1B1
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# define OCRxx OCR1B
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# endif
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#endif
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#ifndef BACKLIGHT_RESOLUTION
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# define BACKLIGHT_RESOLUTION 0xFFFFU
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#endif
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#if (BACKLIGHT_RESOLUTION > 0xFFFF || BACKLIGHT_RESOLUTION < 0x00FF)
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# error "Backlight resolution must be between 0x00FF and 0xFFFF"
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#endif
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#define BREATHING_SCALE_FACTOR F_CPU / BACKLIGHT_RESOLUTION / 120
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static inline void enable_pwm(void) {
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#if BACKLIGHT_ON_STATE == 1
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TCCRxA |= _BV(COMxx1);
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#else
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TCCRxA |= _BV(COMxx1) | _BV(COMxx0);
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#endif
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}
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static inline void disable_pwm(void) {
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#if BACKLIGHT_ON_STATE == 1
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TCCRxA &= ~(_BV(COMxx1));
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#else
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TCCRxA &= ~(_BV(COMxx1) | _BV(COMxx0));
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#endif
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}
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// See http://jared.geek.nz/2013/feb/linear-led-pwm
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static uint16_t cie_lightness(uint16_t v) {
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if (v <= (uint32_t)ICRx / 12) // If the value is less than or equal to ~8% of max
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{
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return v / 9; // Same as dividing by 900%
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} else {
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// In the next two lines values are bit-shifted. This is to avoid loosing decimals in integer math.
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uint32_t y = (((uint32_t)v + (uint32_t)ICRx / 6) << 5) / ((uint32_t)ICRx / 6 + ICRx); // If above 8%, add ~16% of max, and normalize with (max + ~16% max)
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uint32_t out = (y * y * y * ICRx) >> 15; // Cube it and undo the bit-shifting. (which is now three times as much due to the cubing)
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if (out > ICRx) // Avoid overflows
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{
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out = ICRx;
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}
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return (uint16_t)out;
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}
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}
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// rescale the supplied backlight value to be in terms of the value limit // range for val is [0..ICRx]. PWM pin is high while the timer count is below val.
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static uint32_t rescale_limit_val(uint32_t val) {
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return (val * (BACKLIGHT_LIMIT_VAL + 1)) / 256;
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}
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// range for val is [0..ICRx]. PWM pin is high while the timer count is below val.
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static inline void set_pwm(uint16_t val) {
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OCRxx = val;
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}
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void backlight_set(uint8_t level) {
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if (level > BACKLIGHT_LEVELS) level = BACKLIGHT_LEVELS;
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if (level == 0) {
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// Turn off PWM control on backlight pin
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disable_pwm();
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} else {
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// Turn on PWM control of backlight pin
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enable_pwm();
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}
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// Set the brightness
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set_pwm(cie_lightness(rescale_limit_val(ICRx * (uint32_t)level / BACKLIGHT_LEVELS)));
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}
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void backlight_task(void) {}
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#ifdef BACKLIGHT_BREATHING
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# define BREATHING_NO_HALT 0
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# define BREATHING_HALT_OFF 1
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# define BREATHING_HALT_ON 2
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# define BREATHING_STEPS 128
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static uint8_t breathing_halt = BREATHING_NO_HALT;
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static uint16_t breathing_counter = 0;
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static uint8_t breath_scale_counter = 1;
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/* Run the breathing loop at ~120Hz*/
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const uint8_t breathing_ISR_frequency = 120;
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bool is_breathing(void) {
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return !!(TIMSKx & _BV(TOIEx));
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}
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# define breathing_interrupt_enable() \
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do { \
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TIMSKx |= _BV(TOIEx); \
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} while (0)
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# define breathing_interrupt_disable() \
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do { \
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TIMSKx &= ~_BV(TOIEx); \
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} while (0)
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# define breathing_min() \
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do { \
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breathing_counter = 0; \
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} while (0)
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# define breathing_max() \
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do { \
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breathing_counter = get_breathing_period() * breathing_ISR_frequency / 2; \
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} while (0)
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void breathing_enable(void) {
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breathing_counter = 0;
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breathing_halt = BREATHING_NO_HALT;
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breathing_interrupt_enable();
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}
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void breathing_pulse(void) {
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if (get_backlight_level() == 0)
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breathing_min();
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else
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breathing_max();
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breathing_halt = BREATHING_HALT_ON;
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breathing_interrupt_enable();
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}
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void breathing_disable(void) {
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breathing_interrupt_disable();
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// Restore backlight level
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backlight_set(get_backlight_level());
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}
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void breathing_self_disable(void) {
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if (get_backlight_level() == 0)
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breathing_halt = BREATHING_HALT_OFF;
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else
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breathing_halt = BREATHING_HALT_ON;
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}
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/* To generate breathing curve in python:
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* from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)]
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*/
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static const uint8_t breathing_table[BREATHING_STEPS] PROGMEM = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 28, 32, 36, 41, 46, 51, 57, 63, 70, 76, 83, 91, 98, 106, 113, 121, 129, 138, 146, 154, 162, 170, 178, 185, 193, 200, 207, 213, 220, 225, 231, 235, 240, 244, 247, 250, 252, 253, 254, 255, 254, 253, 252, 250, 247, 244, 240, 235, 231, 225, 220, 213, 207, 200, 193, 185, 178, 170, 162, 154, 146, 138, 129, 121, 113, 106, 98, 91, 83, 76, 70, 63, 57, 51, 46, 41, 36, 32, 28, 24, 20, 17, 15, 12, 10, 8, 6, 5, 4, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
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// Use this before the cie_lightness function.
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static inline uint16_t scale_backlight(uint16_t v) {
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return v / BACKLIGHT_LEVELS * get_backlight_level();
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}
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/* Assuming a 16MHz CPU clock and a timer that resets at 64k (ICR1), the following interrupt handler will run
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* about 244 times per second.
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*
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* The following ISR runs at F_CPU/ISRx. With a 16MHz clock and default pwm resolution, that means 244Hz
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*/
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ISR(TIMERx_OVF_vect) {
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// Only run this ISR at ~120 Hz
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if (breath_scale_counter++ == BREATHING_SCALE_FACTOR) {
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breath_scale_counter = 1;
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} else {
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return;
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}
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uint16_t interval = (uint16_t)get_breathing_period() * breathing_ISR_frequency / BREATHING_STEPS;
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// resetting after one period to prevent ugly reset at overflow.
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breathing_counter = (breathing_counter + 1) % (get_breathing_period() * breathing_ISR_frequency);
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uint8_t index = breathing_counter / interval;
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// limit index to max step value
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if (index >= BREATHING_STEPS) {
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index = BREATHING_STEPS - 1;
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}
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if (((breathing_halt == BREATHING_HALT_ON) && (index == BREATHING_STEPS / 2)) || ((breathing_halt == BREATHING_HALT_OFF) && (index == BREATHING_STEPS - 1))) {
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breathing_interrupt_disable();
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}
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// Set PWM to a brightnessvalue scaled to the configured resolution
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set_pwm(cie_lightness(rescale_limit_val(scale_backlight((uint32_t)pgm_read_byte(&breathing_table[index]) * ICRx / 255))));
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}
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#endif // BACKLIGHT_BREATHING
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void backlight_init_ports(void) {
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setPinOutput(BACKLIGHT_PIN);
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#if BACKLIGHT_ON_STATE == 1
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writePinLow(BACKLIGHT_PIN);
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#else
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writePinHigh(BACKLIGHT_PIN);
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#endif
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// I could write a wall of text here to explain... but TL;DW
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// Go read the ATmega32u4 datasheet.
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// And this: http://blog.saikoled.com/post/43165849837/secret-konami-cheat-code-to-high-resolution-pwm-on
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// Pin PB7 = OCR1C (Timer 1, Channel C)
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// Compare Output Mode = Clear on compare match, Channel C = COM1C1=1 COM1C0=0
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// (i.e. start high, go low when counter matches.)
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// WGM Mode 14 (Fast PWM) = WGM13=1 WGM12=1 WGM11=1 WGM10=0
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// Clock Select = clk/1 (no prescaling) = CS12=0 CS11=0 CS10=1
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/*
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14.8.3:
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"In fast PWM mode, the compare units allow generation of PWM waveforms on the OCnx pins. Setting the COMnx1:0 bits to two will produce a non-inverted PWM [..]."
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"In fast PWM mode the counter is incremented until the counter value matches either one of the fixed values 0x00FF, 0x01FF, or 0x03FF (WGMn3:0 = 5, 6, or 7), the value in ICRn (WGMn3:0 = 14), or the value in OCRnA (WGMn3:0 = 15)."
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*/
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TCCRxA = _BV(COMxx1) | _BV(WGM11); // = 0b00001010;
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TCCRxB = _BV(WGM13) | _BV(WGM12) | _BV(CS10); // = 0b00011001;
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ICRx = BACKLIGHT_RESOLUTION;
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backlight_init();
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#ifdef BACKLIGHT_BREATHING
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if (is_backlight_breathing()) {
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breathing_enable();
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}
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#endif
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}
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