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PWM enhancements (phase shifting and dithering) #4115

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PWM enhancements (phase shifting and dithering) #4115

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741b76f
Adding dithering to PWM and proper phase shifting (draft)
DedeHai Aug 25, 2024
8dbba62
code cleanup
DedeHai Aug 25, 2024
718e864
Merge branch 'bus-config' into 0_15_PWM_enhancement
blazoncek Aug 26, 2024
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28 changes: 15 additions & 13 deletions wled00/bus_manager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -402,13 +402,21 @@ BusPwm::BusPwm(BusConfig &bc)
{
if (!isPWM(bc.type)) return;
unsigned numPins = numPWMPins(bc.type);
#ifdef ESP8266
#ifdef ESP8266
_frequency = bc.frequency ? bc.frequency : WLED_PWM_FREQ;
// duty cycle resolution (_depth) can be extracted from this formula: CLOCK_FREQUENCY > _frequency * 2^_depth
for (_depth = MAX_BIT_WIDTH; _depth > 8; _depth--) if (((CLOCK_FREQUENCY/_frequency) >> _depth) > 0) break;
analogWriteRange((1<<_depth)-1);
analogWriteFreq(_frequency);
#else
for (unsigned i = 0; i < numPins; i++) {
uint8_t currentPin = bc.pins[i];
if (!pinManager.allocatePin(currentPin, true, PinOwner::BusPwm)) {
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deallocatePins(); return;
}
_pins[i] = currentPin; //store only after allocatePin() succeeds
pinMode(_pins[i], OUTPUT);
}
#else
_depth = 12; // set to 12bit resolution by default
unsigned ditheringbits = 4;
switch (bc.frequency) { // TODO: this is not the proper way to handle this, could just save the type instead of frequency
Expand All @@ -423,27 +431,21 @@ BusPwm::BusPwm(BusConfig &bc)
if (_ledcStart == 255) { //no more free LEDC channels
deallocatePins(); return;
}
#endif

for (unsigned i = 0; i < numPins; i++) {
uint8_t currentPin = bc.pins[i];
if (!pinManager.allocatePin(currentPin, true, PinOwner::BusPwm)) {
deallocatePins(); return;
}
_pins[i] = currentPin; //store only after allocatePin() succeeds
#ifdef ESP8266
pinMode(_pins[i], OUTPUT);
#else
ledcSetup(_ledcStart + i, _frequency, _depth - ditheringbits); // TODO: if this is a CCT 2 pin strip, first channel must fulfill ch%2==0 so both use the same timer!
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ledcAttachPin(_pins[i], _ledcStart + i);
//#endif
}
// sync the timers (not perfect but better than unsynced)
for (unsigned i = 0; i < numPins; i++) {
uint8_t group = ((_ledcStart + i)/8), timer = (((_ledcStart + i) / 2) % 4);
ledc_timer_rst((ledc_mode_t)group, (ledc_timer_t)timer); // reset timer so PWM channels are in sync
#endif
}
#endif
_hasRgb = hasRGB(bc.type);
_hasWhite = hasWhite(bc.type);
_hasCCT = hasCCT(bc.type);
Expand Down Expand Up @@ -513,7 +515,7 @@ void BusPwm::show() {
if (!_valid) return;
unsigned numPins = getPins();
unsigned maxBri = (1<<_depth); // note: not subtraciting 1 ensures full on when set to max (no gpio glitching)
unsigned* scaledBri = new unsigned[numPins]; // TODO: could use stack with a fixed size if maximum number of pins is known (or is a #define)
unsigned scaledBri[numPins];
unsigned total_dutycycle = maxBri >> 3; // start value to get better distribution
unsigned offsetSum = 0;
[[maybe_unused]] unsigned deadtime = 0;
Expand All @@ -538,7 +540,7 @@ void BusPwm::show() {
for (unsigned i = 0; i < numPins; i++) {
scaledBri[i] = (_data[i] * pwmBri) / 255;
if (_reversed) scaledBri[i] = maxBri - scaledBri[i];
#ifndef ESP8266
#ifdef ARDUINO_ARCH_ESP32
total_dutycycle += scaledBri[i];
#endif
}
Expand All @@ -556,11 +558,12 @@ void BusPwm::show() {
offsetSum += (scaledBri[i]<<_depth) / total_dutycycle;
//phaseoffset = 0;// (maxBri / numPins)*i; // for debugging, can be removed
uint8_t group=((_ledcStart + i)/8), channel=((_ledcStart + i)%8);
//directly write to LEDc struct, no checking is done (assumes correctly assigned channels)
//directly write to LEDc struct as there is no HAL exposed function for dithering. note: no checking is done (assumes correctly assigned channels)
LEDC.channel_group[group].channel[channel].duty.duty = scaledBri[i] << (4 - ditheringbits);
LEDC.channel_group[group].channel[channel].hpoint.hpoint = phaseoffset >> ditheringbits; // offset works with MSBs only
ledc_update_duty((ledc_mode_t)group, (ledc_channel_t)channel);
/*
// debug output, can be removed
Serial.print("IO");
Serial.print(_pins[i]);
Serial.print("\t group:");
Expand All @@ -575,7 +578,6 @@ void BusPwm::show() {
#endif
}
// Serial.println("***");
delete[] scaledBri;
}

uint8_t BusPwm::getPins(uint8_t* pinArray) const {
Expand Down