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backlight: split AVR PWM and timer drivers (#21540)

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Ryan 2023-07-21 09:27:55 +10:00 • committed by GitHub
parent b090354143
commit 4137685f8e
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43 changed files with 570 additions and 317 deletions
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204
platforms/avr/drivers/backlight_pwm.c
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@ -1,5 +1,5 @@
#include "backlight.h"
#include "backlight_driver_common.h"
#include "gpio.h"
#include "progmem.h"
#include <avr/io.h>
#include <avr/interrupt.h>
@ -9,14 +9,6 @@
# 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
@ -122,106 +114,34 @@
# 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
#ifndef BACKLIGHT_RESOLUTION
# define BACKLIGHT_RESOLUTION 0xFFFFU
#endif
#if (BACKLIGHT_RESOLUTION > 0xFFFF || BACKLIGHT_RESOLUTION < 0x00FF)
# error "Backlight resolution must be between 0x00FF and 0xFFFF"
#endif
#define BREATHING_SCALE_FACTOR F_CPU / BACKLIGHT_RESOLUTION / 120
static inline void enable_pwm(void) {
# if BACKLIGHT_ON_STATE == 1
#if BACKLIGHT_ON_STATE == 1
TCCRxA |= _BV(COMxx1);
# else
#else
TCCRxA |= _BV(COMxx1) | _BV(COMxx0);
# endif
#endif
}
static inline void disable_pwm(void) {
# if BACKLIGHT_ON_STATE == 1
#if BACKLIGHT_ON_STATE == 1
TCCRxA &= ~(_BV(COMxx1));
# else
#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
@ -254,26 +174,11 @@ 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)));
@ -282,7 +187,6 @@ void backlight_set(uint8_t level) {
void backlight_task(void) {}
#ifdef BACKLIGHT_BREATHING
# define BREATHING_NO_HALT 0
# define BREATHING_HALT_OFF 1
# define BREATHING_HALT_ON 2
@ -293,39 +197,20 @@ 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
const uint8_t breathing_ISR_frequency = 120;
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_interrupt_enable() \
do { \
TIMSKx |= _BV(TOIEx); \
} while (0)
# define breathing_interrupt_disable() \
do { \
TIMSKx &= ~_BV(TOIEx); \
} while (0)
# define breathing_min() \
do { \
@ -374,20 +259,14 @@ 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
{
ISR(TIMERx_OVF_vect) {
// Only run this ISR at ~120 Hz
if (breath_scale_counter++ == breathing_freq_scale_factor) {
if (breath_scale_counter++ == BREATHING_SCALE_FACTOR) {
breath_scale_counter = 1;
} else {
return;
@ -412,19 +291,17 @@ ISR(TIMERx_OVF_vect)
#endif // BACKLIGHT_BREATHING
void backlight_init_ports(void) {
// Setup backlight pin as output and output to on state.
backlight_pins_init();
setPinOutput(BACKLIGHT_PIN);
#if BACKLIGHT_ON_STATE == 1
writePinLow(BACKLIGHT_PIN);
#else
writePinHigh(BACKLIGHT_PIN);
#endif
// 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.)
@ -438,23 +315,10 @@ void backlight_init_ports(void) {
*/
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
ICRx = BACKLIGHT_RESOLUTION;
backlight_init();
#ifdef BACKLIGHT_BREATHING
if (is_backlight_breathing()) {
breathing_enable();