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fixed offsets and inverted signal plus dead time

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This commit is contained in:
Damian Schneider 2024-09-02 17:53:15 +02:00
parent a3b28871c6
commit 85e2f7eb34
1 changed files with 43 additions and 20 deletions
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63
wled00/bus_manager.cpp
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@ -410,6 +410,7 @@ BusPwm::BusPwm(BusConfig &bc)
{
if (!isPWM(bc.type)) return;
unsigned numPins = numPWMPins(bc.type);
unsigned dithering = 0;
_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;
@ -428,7 +429,10 @@ BusPwm::BusPwm(BusConfig &bc)
pinManager.deallocateMultiplePins(pins, numPins, PinOwner::BusPwm);
return;
}
if (_needsRefresh) _depth = 8; // fixed 8 bit depth with 4 bit dithering (ESP8266 has no hardware to support dithering)
if (_needsRefresh) {
_depth = 12; // fixed 8 bit depth PWM with 4 bit dithering (ESP8266 has no hardware to support dithering)
dithering = 4;
}
#endif
for (unsigned i = 0; i < numPins; i++) {
@ -437,7 +441,7 @@ BusPwm::BusPwm(BusConfig &bc)
pinMode(_pins[i], OUTPUT);
#else
unsigned channel = _ledcStart + i;
ledcSetup(channel, _frequency, _depth);
ledcSetup(channel, _frequency, _depth - dithering);
ledcAttachPin(_pins[i], channel);
// LEDC timer reset credit @dedehai
uint8_t group = (channel / 8), timer = ((channel / 2) % 4); // same fromula as in ledcSetup()
@ -511,8 +515,11 @@ uint32_t BusPwm::getPixelColor(uint16_t pix) const {
void BusPwm::show() {
if (!_valid) return;
bool dithering = _needsRefresh; // avoid working with bitfield
const unsigned numPins = getPins();
const unsigned maxBri = (1<<_depth); // possible values: 16384 (14), 8192 (13), 4096 (12), 2048 (11), 1024 (10), 512 (9) and 256 (8)
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 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
@ -525,41 +532,37 @@ void BusPwm::show() {
// cubic response for values [21-255]
pwmBri += 4080;
float temp = (float)pwmBri / 29580.0f;
temp = temp * temp * temp * 4095.0f;
temp = temp * temp * temp * (float)maxBri;
pwmBri = (unsigned)temp;
}
// pwmBri is in range [0-4095]
// determine phase shift
[[maybe_unused]] unsigned phaseOffset = maxBri / numPins; // (maxBri is at _depth resolution)
// we will be phase shifting every channel by fixed amount (i times /2 or /3 or /4 or /5)
// phase shifting is only mandatory when using H-bridge to drive reverse-polarity PWM CCT (2 wire) LED type (with 180° phase)
unsigned phaseOffset = 0;
// we will be phase shifting every channel by previous pulse length (plus dead time if required)
// 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
[[maybe_unused]] bool cctOverlap = (_type == TYPE_ANALOG_2CH) && (_data[0]+_data[1] >= 254);
// 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)
bool dithering = _needsRefresh; // avoid working with bitfield
for (unsigned i = 0; i < numPins; i++) {
unsigned scaled = (_data[i] * pwmBri) / 255; // scaled is at 12 bit depth (same as pwmBri)
// adjust "scaled" value (to fit resolution bounds)
if (_depth < 12 && !dithering) scaled >>= 12 - _depth; // normalize scaled value (if not using dithering)
else if (_depth > 12) scaled <<= _depth - 12; // scale to _depth if using >12 bit
if (_reversed) scaled = maxBri - scaled;
unsigned scaled = (_data[i] * pwmBri) / 255;
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 for H-bridge
// pinManager will make sure both LEDC channels are in the same speed group and sharing the same timer
// so we only need to take care of shortening the signal at 50% distribution for 1 pulse
if (cctOverlap && Bus::getCCTBlend() == 0) {
unsigned shift = (dithering*4);
unsigned briLimit = phaseOffset << shift; // expand limit if using dithering
if (scaled >= briLimit) scaled = briLimit - (1<<shift); // safety check & 1 pulse dead time when brightness is at 50%
// 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 gr = channel/8; // high/low speed group
unsigned ch = channel%8; // group channel
@ -571,8 +574,28 @@ void BusPwm::show() {
LEDC.channel_group[gr].channel[ch].hpoint.hpoint = phaseOffset*i; // phaseOffset is at _depth resolution (8 bit)
LEDC_MUTEX_UNLOCK();
ledc_update_duty((ledc_mode_t)gr, (ledc_channel_t)ch);
phaseOffset += ((scaled + (maxBri - scaled) / 2) >> bithsift) + 1; // fixed 180°, add 1 pulse for dead time (min pulse with dithering is 8bit)
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
Serial.print(" maxbri = ");
Serial.print(maxBri);
Serial.print(" offset = ");
Serial.print(phaseOffset);
Serial.print(" bit depth = ");
Serial.print(_depth);
Serial.print(" freq = ");
Serial.print(_frequency);
Serial.print(" scaled= ");
Serial.println(scaled);
Serial.print(" duty = ");
Serial.println(LEDC.channel_group[gr].channel[ch].duty.duty);
#endif
}
Serial.println("*********");
}
uint8_t BusPwm::getPins(uint8_t* pinArray) const {