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-rw-r--r--platforms/avr/drivers/backlight_pwm.c463
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diff --git a/platforms/avr/drivers/backlight_pwm.c b/platforms/avr/drivers/backlight_pwm.c
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+++ b/platforms/avr/drivers/backlight_pwm.c
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+#include "backlight.h"
+#include "backlight_driver_common.h"
+#include "progmem.h"
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+// Maximum duty cycle limit
+#ifndef BACKLIGHT_LIMIT_VAL
+# define BACKLIGHT_LIMIT_VAL 255
+#endif
+
+// This logic is a bit complex, we support 3 setups:
+//
+// 1. Hardware PWM when backlight is wired to a PWM pin.
+// Depending on this pin, we use a different output compare unit.
+// 2. Software PWM with hardware timers, but the used timer
+// depends on the Audio setup (Audio wins over Backlight).
+// 3. Full software PWM, driven by the matrix scan, if both timers are used by Audio.
+
+#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)
+# define ICRx ICR1
+# define TCCRxA TCCR1A
+# define TCCRxB TCCR1B
+# define TIMERx_OVF_vect TIMER1_OVF_vect
+# define TIMSKx TIMSK1
+# define TOIEx TOIE1
+
+# if BACKLIGHT_PIN == B5
+# define COMxx0 COM1A0
+# define COMxx1 COM1A1
+# define OCRxx OCR1A
+# elif BACKLIGHT_PIN == B6
+# define COMxx0 COM1B0
+# define COMxx1 COM1B1
+# define OCRxx OCR1B
+# elif BACKLIGHT_PIN == B7
+# define COMxx0 COM1C0
+# define COMxx1 COM1C1
+# define OCRxx OCR1C
+# endif
+#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)
+# define ICRx ICR3
+# define TCCRxA TCCR3A
+# define TCCRxB TCCR3B
+# define TIMERx_OVF_vect TIMER3_OVF_vect
+# define TIMSKx TIMSK3
+# define TOIEx TOIE3
+
+# if BACKLIGHT_PIN == C4
+# if (defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__))
+# error This MCU has no C4 pin!
+# else
+# define COMxx0 COM3C0
+# define COMxx1 COM3C1
+# define OCRxx OCR3C
+# endif
+# elif BACKLIGHT_PIN == C5
+# if (defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__))
+# error This MCU has no C5 pin!
+# else
+# define COMxx0 COM3B0
+# define COMxx1 COM3B1
+# define OCRxx OCR3B
+# endif
+# elif BACKLIGHT_PIN == C6
+# define COMxx0 COM3A0
+# define COMxx1 COM3A1
+# define OCRxx OCR3A
+# endif
+#elif (defined(__AVR_AT90USB162__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega32U2__)) && (BACKLIGHT_PIN == B7 || BACKLIGHT_PIN == C5 || BACKLIGHT_PIN == C6)
+# define ICRx ICR1
+# define TCCRxA TCCR1A
+# define TCCRxB TCCR1B
+# define TIMERx_OVF_vect TIMER1_OVF_vect
+# define TIMSKx TIMSK1
+# define TOIEx TOIE1
+
+# if BACKLIGHT_PIN == B7
+# define COMxx0 COM1C0
+# define COMxx1 COM1C1
+# define OCRxx OCR1C
+# elif BACKLIGHT_PIN == C5
+# define COMxx0 COM1B0
+# define COMxx1 COM1B1
+# define OCRxx OCR1B
+# elif BACKLIGHT_PIN == C6
+# define COMxx0 COM1A0
+# define COMxx1 COM1A1
+# define OCRxx OCR1A
+# endif
+#elif defined(__AVR_ATmega32A__) && (BACKLIGHT_PIN == D4 || BACKLIGHT_PIN == D5)
+# define ICRx ICR1
+# define TCCRxA TCCR1A
+# define TCCRxB TCCR1B
+# define TIMERx_OVF_vect TIMER1_OVF_vect
+# define TIMSKx TIMSK
+# define TOIEx TOIE1
+
+# if BACKLIGHT_PIN == D4
+# define COMxx0 COM1B0
+# define COMxx1 COM1B1
+# define OCRxx OCR1B
+# elif BACKLIGHT_PIN == D5
+# define COMxx0 COM1A0
+# define COMxx1 COM1A1
+# define OCRxx OCR1A
+# endif
+#elif (defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)) && (BACKLIGHT_PIN == B1 || BACKLIGHT_PIN == B2)
+# define ICRx ICR1
+# define TCCRxA TCCR1A
+# define TCCRxB TCCR1B
+# define TIMERx_OVF_vect TIMER1_OVF_vect
+# define TIMSKx TIMSK1
+# define TOIEx TOIE1
+
+# if BACKLIGHT_PIN == B1
+# define COMxx0 COM1A0
+# define COMxx1 COM1A1
+# define OCRxx OCR1A
+# elif BACKLIGHT_PIN == B2
+# define COMxx0 COM1B0
+# define COMxx1 COM1B1
+# define OCRxx OCR1B
+# endif
+#elif (AUDIO_PIN != B5) && (AUDIO_PIN != B6) && (AUDIO_PIN != B7) && (AUDIO_PIN_ALT != B5) && (AUDIO_PIN_ALT != B6) && (AUDIO_PIN_ALT != B7)
+// Timer 1 is not in use by Audio feature, Backlight can use it
+# pragma message "Using hardware timer 1 with software PWM"
+# define BACKLIGHT_PWM_TIMER
+# define ICRx ICR1
+# define TCCRxA TCCR1A
+# define TCCRxB TCCR1B
+# define TIMERx_COMPA_vect TIMER1_COMPA_vect
+# define TIMERx_OVF_vect TIMER1_OVF_vect
+# if defined(__AVR_ATmega32A__) // This MCU has only one TIMSK register
+# define TIMSKx TIMSK
+# else
+# define TIMSKx TIMSK1
+# endif
+# define TOIEx TOIE1
+
+# define OCIExA OCIE1A
+# define OCRxx OCR1A
+#elif (AUDIO_PIN != C4) && (AUDIO_PIN != C5) && (AUDIO_PIN != C6)
+# pragma message "Using hardware timer 3 with software PWM"
+// Timer 3 is not in use by Audio feature, Backlight can use it
+# define BACKLIGHT_PWM_TIMER
+# define ICRx ICR1
+# define TCCRxA TCCR3A
+# define TCCRxB TCCR3B
+# define TIMERx_COMPA_vect TIMER3_COMPA_vect
+# define TIMERx_OVF_vect TIMER3_OVF_vect
+# define TIMSKx TIMSK3
+# define TOIEx TOIE3
+
+# define OCIExA OCIE3A
+# define OCRxx OCR3A
+#endif
+
+#ifndef BACKLIGHT_PWM_TIMER // pwm through software
+
+static inline void enable_pwm(void) {
+# if BACKLIGHT_ON_STATE == 1
+ TCCRxA |= _BV(COMxx1);
+# else
+ TCCRxA |= _BV(COMxx1) | _BV(COMxx0);
+# endif
+}
+
+static inline void disable_pwm(void) {
+# if BACKLIGHT_ON_STATE == 1
+ TCCRxA &= ~(_BV(COMxx1));
+# else
+ TCCRxA &= ~(_BV(COMxx1) | _BV(COMxx0));
+# endif
+}
+
+#endif
+
+#ifdef BACKLIGHT_PWM_TIMER
+
+// The idea of software PWM assisted by hardware timers is the following
+// we use the hardware timer in fast PWM mode like for hardware PWM, but
+// instead of letting the Output Match Comparator control the led pin
+// (which is not possible since the backlight is not wired to PWM pins on the
+// CPU), we do the LED on/off by oursleves.
+// The timer is setup to count up to 0xFFFF, and we set the Output Compare
+// register to the current 16bits backlight level (after CIE correction).
+// This means the CPU will trigger a compare match interrupt when the counter
+// reaches the backlight level, where we turn off the LEDs,
+// but also an overflow interrupt when the counter rolls back to 0,
+// in which we're going to turn on the LEDs.
+// The LED will then be on for OCRxx/0xFFFF time, adjusted every 244Hz,
+// or F_CPU/BACKLIGHT_CUSTOM_RESOLUTION if used.
+
+// Triggered when the counter reaches the OCRx value
+ISR(TIMERx_COMPA_vect) {
+ backlight_pins_off();
+}
+
+// Triggered when the counter reaches the TOP value
+// this one triggers at F_CPU/ICRx = 16MHz/65536 =~ 244 Hz
+ISR(TIMERx_OVF_vect) {
+# ifdef BACKLIGHT_BREATHING
+ if (is_breathing()) {
+ breathing_task();
+ }
+# endif
+ // for very small values of OCRxx (or backlight level)
+ // we can't guarantee this whole code won't execute
+ // at the same time as the compare match interrupt
+ // which means that we might turn on the leds while
+ // trying to turn them off, leading to flickering
+ // artifacts (especially while breathing, because breathing_task
+ // takes many computation cycles).
+ // so better not turn them on while the counter TOP is very low.
+ if (OCRxx > ICRx / 250 + 5) {
+ backlight_pins_on();
+ }
+}
+
+#endif
+
+#define TIMER_TOP 0xFFFFU
+
+// See http://jared.geek.nz/2013/feb/linear-led-pwm
+static uint16_t cie_lightness(uint16_t v) {
+ if (v <= (uint32_t)ICRx / 12) // If the value is less than or equal to ~8% of max
+ {
+ return v / 9; // Same as dividing by 900%
+ } else {
+ // In the next two lines values are bit-shifted. This is to avoid loosing decimals in integer math.
+ 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)
+ 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)
+
+ if (out > ICRx) // Avoid overflows
+ {
+ out = ICRx;
+ }
+ return (uint16_t)out;
+ }
+}
+
+// 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.
+static uint32_t rescale_limit_val(uint32_t val) {
+ return (val * (BACKLIGHT_LIMIT_VAL + 1)) / 256;
+}
+
+// range for val is [0..ICRx]. PWM pin is high while the timer count is below val.
+static inline void set_pwm(uint16_t val) {
+ OCRxx = val;
+}
+
+void backlight_set(uint8_t level) {
+ if (level > BACKLIGHT_LEVELS) level = BACKLIGHT_LEVELS;
+
+ if (level == 0) {
+#ifdef BACKLIGHT_PWM_TIMER
+ if (OCRxx) {
+ TIMSKx &= ~(_BV(OCIExA));
+ TIMSKx &= ~(_BV(TOIEx));
+ }
+#else
+ // Turn off PWM control on backlight pin
+ disable_pwm();
+#endif
+ backlight_pins_off();
+ } else {
+#ifdef BACKLIGHT_PWM_TIMER
+ if (!OCRxx) {
+ TIMSKx |= _BV(OCIExA);
+ TIMSKx |= _BV(TOIEx);
+ }
+#else
+ // Turn on PWM control of backlight pin
+ enable_pwm();
+#endif
+ }
+ // Set the brightness
+ set_pwm(cie_lightness(rescale_limit_val(ICRx * (uint32_t)level / BACKLIGHT_LEVELS)));
+}
+
+void backlight_task(void) {}
+
+#ifdef BACKLIGHT_BREATHING
+
+# define BREATHING_NO_HALT 0
+# define BREATHING_HALT_OFF 1
+# define BREATHING_HALT_ON 2
+# define BREATHING_STEPS 128
+
+static uint8_t breathing_halt = BREATHING_NO_HALT;
+static uint16_t breathing_counter = 0;
+
+static uint8_t breath_scale_counter = 1;
+/* Run the breathing loop at ~120Hz*/
+const uint8_t breathing_ISR_frequency = 120;
+static uint16_t breathing_freq_scale_factor = 2;
+
+# ifdef BACKLIGHT_PWM_TIMER
+static bool breathing = false;
+
+bool is_breathing(void) {
+ return breathing;
+}
+
+# define breathing_interrupt_enable() \
+ do { \
+ breathing = true; \
+ } while (0)
+# define breathing_interrupt_disable() \
+ do { \
+ breathing = false; \
+ } while (0)
+# else
+
+bool is_breathing(void) {
+ return !!(TIMSKx & _BV(TOIEx));
+}
+
+# define breathing_interrupt_enable() \
+ do { \
+ TIMSKx |= _BV(TOIEx); \
+ } while (0)
+# define breathing_interrupt_disable() \
+ do { \
+ TIMSKx &= ~_BV(TOIEx); \
+ } while (0)
+# endif
+
+# define breathing_min() \
+ do { \
+ breathing_counter = 0; \
+ } while (0)
+# define breathing_max() \
+ do { \
+ breathing_counter = get_breathing_period() * breathing_ISR_frequency / 2; \
+ } while (0)
+
+void breathing_enable(void) {
+ breathing_counter = 0;
+ breathing_halt = BREATHING_NO_HALT;
+ breathing_interrupt_enable();
+}
+
+void breathing_pulse(void) {
+ if (get_backlight_level() == 0)
+ breathing_min();
+ else
+ breathing_max();
+ breathing_halt = BREATHING_HALT_ON;
+ breathing_interrupt_enable();
+}
+
+void breathing_disable(void) {
+ breathing_interrupt_disable();
+ // Restore backlight level
+ backlight_set(get_backlight_level());
+}
+
+void breathing_self_disable(void) {
+ if (get_backlight_level() == 0)
+ breathing_halt = BREATHING_HALT_OFF;
+ else
+ breathing_halt = BREATHING_HALT_ON;
+}
+
+/* To generate breathing curve in python:
+ * from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)]
+ */
+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};
+
+// Use this before the cie_lightness function.
+static inline uint16_t scale_backlight(uint16_t v) {
+ return v / BACKLIGHT_LEVELS * get_backlight_level();
+}
+
+# ifdef BACKLIGHT_PWM_TIMER
+void breathing_task(void)
+# else
+/* Assuming a 16MHz CPU clock and a timer that resets at 64k (ICR1), the following interrupt handler will run
+ * about 244 times per second.
+ *
+ * The following ISR runs at F_CPU/ISRx. With a 16MHz clock and default pwm resolution, that means 244Hz
+ */
+ISR(TIMERx_OVF_vect)
+# endif
+{
+
+ // Only run this ISR at ~120 Hz
+ if (breath_scale_counter++ == breathing_freq_scale_factor) {
+ breath_scale_counter = 1;
+ } else {
+ return;
+ }
+ uint16_t interval = (uint16_t)get_breathing_period() * breathing_ISR_frequency / BREATHING_STEPS;
+ // resetting after one period to prevent ugly reset at overflow.
+ breathing_counter = (breathing_counter + 1) % (get_breathing_period() * breathing_ISR_frequency);
+ uint8_t index = breathing_counter / interval;
+ // limit index to max step value
+ if (index >= BREATHING_STEPS) {
+ index = BREATHING_STEPS - 1;
+ }
+
+ if (((breathing_halt == BREATHING_HALT_ON) && (index == BREATHING_STEPS / 2)) || ((breathing_halt == BREATHING_HALT_OFF) && (index == BREATHING_STEPS - 1))) {
+ breathing_interrupt_disable();
+ }
+
+ // Set PWM to a brightnessvalue scaled to the configured resolution
+ set_pwm(cie_lightness(rescale_limit_val(scale_backlight((uint32_t)pgm_read_byte(&breathing_table[index]) * ICRx / 255))));
+}
+
+#endif // BACKLIGHT_BREATHING
+
+void backlight_init_ports(void) {
+ // Setup backlight pin as output and output to on state.
+ backlight_pins_init();
+
+ // I could write a wall of text here to explain... but TL;DW
+ // Go read the ATmega32u4 datasheet.
+ // And this: http://blog.saikoled.com/post/43165849837/secret-konami-cheat-code-to-high-resolution-pwm-on
+
+#ifdef BACKLIGHT_PWM_TIMER
+ // TimerX setup, Fast PWM mode count to TOP set in ICRx
+ TCCRxA = _BV(WGM11); // = 0b00000010;
+ // clock select clk/1
+ TCCRxB = _BV(WGM13) | _BV(WGM12) | _BV(CS10); // = 0b00011001;
+#else // hardware PWM
+ // Pin PB7 = OCR1C (Timer 1, Channel C)
+ // Compare Output Mode = Clear on compare match, Channel C = COM1C1=1 COM1C0=0
+ // (i.e. start high, go low when counter matches.)
+ // WGM Mode 14 (Fast PWM) = WGM13=1 WGM12=1 WGM11=1 WGM10=0
+ // Clock Select = clk/1 (no prescaling) = CS12=0 CS11=0 CS10=1
+
+ /*
+ 14.8.3:
+ "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 [..]."
+ "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)."
+ */
+ TCCRxA = _BV(COMxx1) | _BV(WGM11); // = 0b00001010;
+ TCCRxB = _BV(WGM13) | _BV(WGM12) | _BV(CS10); // = 0b00011001;
+#endif
+
+#ifdef BACKLIGHT_CUSTOM_RESOLUTION
+# if (BACKLIGHT_CUSTOM_RESOLUTION > 0xFFFF || BACKLIGHT_CUSTOM_RESOLUTION < 1)
+# error "This out of range of the timer capabilities"
+# elif (BACKLIGHT_CUSTOM_RESOLUTION < 0xFF)
+# warning "Resolution lower than 0xFF isn't recommended"
+# endif
+# ifdef BACKLIGHT_BREATHING
+ breathing_freq_scale_factor = F_CPU / BACKLIGHT_CUSTOM_RESOLUTION / 120;
+# endif
+ ICRx = BACKLIGHT_CUSTOM_RESOLUTION;
+#else
+ ICRx = TIMER_TOP;
+#endif
+
+ backlight_init();
+#ifdef BACKLIGHT_BREATHING
+ if (is_backlight_breathing()) {
+ breathing_enable();
+ }
+#endif
+}