diff --git a/wled00/bus_manager.cpp b/wled00/bus_manager.cpp index 4d12c93b6..ef7df007d 100644 --- a/wled00/bus_manager.cpp +++ b/wled00/bus_manager.cpp @@ -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 +429,11 @@ 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 is true (UI hack) we are using dithering (credit @dedehai & @zalatnaicsongor) + 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 +442,7 @@ 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 +516,12 @@ uint32_t BusPwm::getPixelColor(uint16_t pix) const { void BusPwm::show() { if (!_valid) return; + // 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) + const 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); // possible values: 16384 (14), 8192 (13), 4096 (12), 2048 (11), 1024 (10), 512 (9) and 256 (8) + const unsigned bitShift = dithering * 4; // if dithering, _depth is 12 bit but LEDC channel is set to 8 bit (using 4 fractional bits) // 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 @@ -525,52 +534,42 @@ void BusPwm::show() { // cubic response for values [21-255] pwmBri += 4080; float temp = (float)pwmBri / 29580.0f; - temp = temp * temp * temp * 4095.0f; - pwmBri = (unsigned)temp; + temp = temp * temp * temp * (float)maxBri; + pwmBri = (unsigned)temp; // pwmBri is in range [0-maxBri] } - // 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) - // CCT additive blending must be 0 (WW & CW must not overlap) in such case + [[maybe_unused]] unsigned hPoint = 0; // phase shift (0 - maxBri) + // 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 will not overlap) otherwise signals *will* overlap // 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 - + // Phase shifting requires that LEDC timers are synchronised (see setup()). For PWM CCT (and H-bridge) it is + // also mandatory that both channels use the same timer (pinManager takes care of that). 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; - // scaled is now at _depth resolution (8-14 bits) except when using dithering, 12 bit in such case + unsigned duty = (_data[i] * pwmBri) / 255; #ifdef ESP8266 - analogWrite(_pins[i], scaled); + if (_reversed) duty = maxBri - duty; + analogWrite(_pins[i], duty); #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<= 254 && duty >= maxBri / 2 && duty < maxBri) duty -= deadTime << 1; // shorten duty of larger signal except if full on + if (_reversed) deadTime = -deadTime; // need to invert dead time to make phaseshift go the opposite way so low signals dont overlap } + if (_reversed) duty = maxBri - duty; + 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_MUTEX_UNLOCK(); + LEDC.channel_group[gr].channel[ch].duty.duty = duty << ((!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 = hPoint >> bitShift; // hPoint is at _depth resolution (needs shifting if dithering) ledc_update_duty((ledc_mode_t)gr, (ledc_channel_t)ch); + hPoint += duty + deadTime; // offset to cascade the signals + if (hPoint >= maxBri) hPoint = 0; // offset it out of bounds, reset #endif } }