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Bugfixes

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- fixed maxBri value
- fixed overflow in dead time subtraction
- deadtime and offset now also work if signals are inverted (_reversed)
This commit is contained in:
Damian Schneider 2024-09-03 19:14:50 +02:00
parent be7475fe66
commit 2cc0aceac7
1 changed files with 17 additions and 20 deletions
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37
wled00/bus_manager.cpp
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@ -517,10 +517,8 @@ void BusPwm::show() {
if (!_valid) return;
bool dithering = _needsRefresh; // avoid working with bitfield
const unsigned numPins = getPins();
const unsigned maxBri = (1<<_depth) + 1; // possible values: 16384 (14), 8192 (13), 4096 (12), 2048 (11), 1024 (10), 512 (9) and 256 (8) note: +1 ensures 'full on' (else there is one low pulse period at 100% dutycycle)
const unsigned maxBri = (1<<_depth); // possible values: 16384 (14), 8192 (13), 4096 (12), 2048 (11), 1024 (10), 512 (9) and 256 (8)
const unsigned bithsift = dithering * 4;
//const unsigned maxBri = (1<<_depth) << (dithering*4); // possible values: 16384 (14), 8192 (13), 4096 (12), 2048 (11), 1024 (10), 512 (9) and 256 (8)
// use CIE brightness formula (cubic) to fit (or approximate linearity of) human eye perceived brightness
// the formula is based on 12 bit resolution as there is no need for greater precision
// see: https://en.wikipedia.org/wiki/Lightness
@ -540,38 +538,37 @@ void BusPwm::show() {
// phase shifting is only mandatory when using H-bridge to drive reverse-polarity PWM CCT (2 wire) LED type
// CCT additive blending must be 0 (WW & CW must not overlap) in such case
// for all other cases it will just try to "spread" the load on PSU
// if _needsRefresh is true (UI hack) we are using dithering (credit @dedehai & @zalatnaicsongor)
// https://github.com/Aircoookie/WLED/pull/4115 and https://github.com/zalatnaicsongor/WLED/pull/1)
for (unsigned i = 0; i < numPins; i++) {
unsigned scaled = (_data[i] * pwmBri) / 255;
if (_reversed) scaled = maxBri - scaled;
// prevent overlapping PWM signals (required for H-bridge driven CCT strips)
// pinManager will make sure both LEDC channels are in the same speed group and sharing the same timer (i.e. they are in sync)
// we only need to take care of shortening the signal at full brightness, otherwise the pulses overlap with CCTBlend() == 0
signed deadtime = 0; // add dead time when brightness is 100% (when using dithering, two full 8bit pulses are required, in non-dithering one extra pulse does not hurt at all note: actually could add dead time only if global brightness is also at 255
if (_type == TYPE_ANALOG_2CH && Bus::getCCTBlend() == 0) {
deadtime = 2 << bithsift;
if (_bri == 255 && scaled >= deadtime) scaled -= deadtime;
//another way (maybe more elegant?) of doing this would be to limit bus brightness to 254 if CCT is enabled with zero blending
if(_reversed) deadtime = -deadtime; // need to invert dead time at this point: phaseshift needs to go the opposite way so low signals dont overlap
}
if (_reversed) scaled = maxBri - scaled;
// scaled is now at _depth resolution (8-14 bits) except when using dithering, 12 bit in such case
#ifdef ESP8266
analogWrite(_pins[i], scaled);
#else
unsigned channel = _ledcStart + i;
// prevent overlapping PWM signals (required for H-bridge driven CCT strips)
// pinManager will make sure both LEDC channels are in the same speed group and sharing the same timer (i.e. they are in sync)
// we only need to take care of shortening the signal at full brightness, otherwise the pulses cannot overlap with CCTBlend() == 0
if (_type == TYPE_ANALOG_2CH && Bus::getCCTBlend() == 0) {
if (_bri==255) scaled -= 2 << bithsift; // add dead time when brightness is 100% (when using dithering, two full 8bit pulses are required, in non-dithering one extra pulse does not hurt at all note: actually could add dead time only if global brightness is also at 255
//another way (maybe more elegant?) of doing this would be to limit bus brightness to 254 if CCT is enabled with zero blending (
}
unsigned channel = _ledcStart + i;
unsigned gr = channel/8; // high/low speed group
unsigned ch = channel%8; // group channel
// directly write to LEDC struct as there is no HAL exposed function for dithering
// duty has 20 bit resolution with 4 fractional bits (24 bits in total)
// _depth is 8 bit in this case (and maxBri==256), scaled is still at 12 bit
LEDC_MUTEX_LOCK();
LEDC.channel_group[gr].channel[ch].duty.duty = scaled << ((!dithering)*4); // write full 12 bit value (4 dithering bits)
LEDC.channel_group[gr].channel[ch].hpoint.hpoint = phaseOffset*i; // phaseOffset is at _depth resolution (8 bit)
LEDC.channel_group[gr].channel[ch].duty.duty = scaled << ((!dithering)*4); // lowest 4 bits are used for dithering, shift by 4 bits if not using dithering
LEDC.channel_group[gr].channel[ch].hpoint.hpoint = phaseOffset;
LEDC_MUTEX_UNLOCK();
ledc_update_duty((ledc_mode_t)gr, (ledc_channel_t)ch);
phaseOffset += 2 + (scaled >> bithsift); // offset to cascade the signals, dithering requires two pulses and in non-dithering the extra pulse does not hurt
if(phaseOffset >= maxBri >> bithsift) phaseOffset = 0; // offset it out of bounds, reset TODO: maybe this should be (maxBri-1), need to test
phaseOffset += ((scaled + deadtime) >> bithsift); // offset to cascade the signals, add dead time if required (to ensure pulses do not overlap)
if(phaseOffset >= maxBri >> bithsift) phaseOffset = 0; // offset it out of bounds, reset
#endif
}
}