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Experimental: H-bridge safe mode for TYPE_ANALOG_2CH (cheap hardware?) #5442

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Experimental: H-bridge safe mode for TYPE_ANALOG_2CH (cheap hardware?) #5442

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7e9dc56
Add H-bridge compatible mode for TYPE_ANALOG_2CH_HBRIDGE (mutually ex…
bsvdoom Mar 23, 2026
8311698
break fix
bsvdoom Mar 24, 2026
e9adf19
fix animations: use brightness instead of white balance
bsvdoom Mar 27, 2026
63dd66f
revert parenthesis
bsvdoom Mar 27, 2026
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17 changes: 16 additions & 1 deletion wled00/bus_manager.cpp
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Expand Up @@ -454,6 +454,19 @@ void BusPwm::setPixelColor(unsigned pix, uint32_t c) {
Bus::calculateCCT(c, _data[0], _data[1]);
}
break;
case TYPE_ANALOG_2CH_HBRIDGE: //warm white + cold white, relies on auto white calculation, uses H-bridge for better dimming performance at low brightness
{
uint8_t level = (Bus::_cct < 0 || Bus::_cct > 255) ? 127 : Bus::_cct;
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@softhack007 softhack007 Mar 23, 2026

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int16_t Bus::_cct = -1;     // -1 means use approximateKelvinFromRGB(), 0-255 is standard, >1900 use colorBalanceFromKelvin()

The white from auto-white calculation is in w; Bus::_cct has the color temperature, either in kelvin or directly from the "cct" slider.

uint8_t brightness = w;

if (level <= 127) {
_data[0] = (map(level, 0, 127, 255, 0) * brightness) / 255;
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@softhack007 softhack007 Mar 23, 2026 •
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The use of map() is not ideal here, because it leads to jumps in the final brightness result that can be avoided:

   if (level <= 127) { 
        data[0] = (127-level) * brightness) / 127;   // ramp down, brightest at 0
[...]
   } else {
        data[1] = ((level-128) * brightness) / 127;  // ramp up, brightest at 255
[...]
   }

EDIT: I've initially overlooked the direction of your "map". I've corrected my proposal accordingly.

_data[1] = 0;
} else {
_data[0] = 0;
_data[1] = (map(level, 128, 255, 0, 255) * brightness) / 255;
}
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}
case TYPE_ANALOG_5CH: //RGB + warm white + cold white
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if (cctICused)
_data[4] = Bus::_cct < 0 || Bus::_cct > 255 ? 127 : Bus::_cct;
Expand All @@ -475,6 +488,7 @@ uint32_t BusPwm::getPixelColor(unsigned pix) const {
case TYPE_ANALOG_1CH: //one channel (white), relies on auto white calculation
return RGBW32(0, 0, 0, _data[0]);
case TYPE_ANALOG_2CH: //warm white + cold white
case TYPE_ANALOG_2CH_HBRIDGE: //warm white + cold white, relies on auto white calculation, uses H-bridge for better dimming performance at low brightness
if (cctICused) return RGBW32(0, 0, 0, _data[0]);
else return RGBW32(0, 0, 0, _data[0] + _data[1]);
case TYPE_ANALOG_5CH: //RGB + warm white + cold white
Expand Down Expand Up @@ -525,7 +539,7 @@ void BusPwm::show() {
unsigned duty = (_data[i] * pwmBri) / 255;
unsigned deadTime = 0;

if (_type == TYPE_ANALOG_2CH && Bus::_cctBlend == 0) {
if ((_type == TYPE_ANALOG_2CH || _type == TYPE_ANALOG_2CH_HBRIDGE) && Bus::_cctBlend == 0) {
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@DedeHai DedeHai Mar 24, 2026

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this is what I meant, you add a new type that is already supported by simply setting cctblend=0.

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@bsvdoom bsvdoom Mar 24, 2026

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Regardless of setting cctblend=0, the signal on the tow outputs (A and B) are not a complimentary inverted signal that could drive a H-bridge, the truth table is not satisfied.
kép

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@DedeHai DedeHai Mar 24, 2026

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they are complementary, I spent quite a few hours writing that code. If they are not complementary for the C6, changing setpixelcolor() will not make it so, you need to implement/change the driver.

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@softhack007 softhack007 Mar 24, 2026 •
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Regardless of setting cctblend=0

@bsvdoom did you test the settings suggested by @DedeHai? Did you measure (logic analyzer needed) how it behaves with respect to avoiding shot-through?

@DedeHai I'd say lets short the discussion - my understanding is

  • PWM output on C6 (and C5, too) needs a complete re-write due to major changes in esp-idf. Building anything on top of the broken "V5-C6" analog driver code is like building a house in quicksand - wasted effort.
  • I'm not sure about the specifics of H-Bridges, but the code in this PR just changes the color temperature slider into a left-or-right slider for two LEDs.
  • The output will be BLACK in the middle values, Left = 100% WW, right = 100% CW.
  • Advanced white handling is not supported.

I don't see added value for WLED users. Especially when we already have a working solution for H-Bridge in main.

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@DedeHai DedeHai Mar 24, 2026

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agreed, as with all C6 / V5 code, it should be done properly to avoid a patchwork of fixes that then have to be re-adjusted later. By properly I mean write a driver that does the same as current main.

// add dead time between signals (when using dithering, two full 8bit pulses are required)
deadTime = (1+dithering) << bitShift;
// we only need to take care of shortening the signal at (almost) full brightness otherwise pulses may overlap
Expand Down Expand Up @@ -579,6 +593,7 @@ std::vector<LEDType> BusPwm::getLEDTypes() {
return {
{TYPE_ANALOG_1CH, "A", PSTR("PWM White")},
{TYPE_ANALOG_2CH, "AA", PSTR("PWM CCT")},
{TYPE_ANALOG_2CH_HBRIDGE, "AA", PSTR("PWM CCT (H-bridge)")},
{TYPE_ANALOG_3CH, "AAA", PSTR("PWM RGB")},
{TYPE_ANALOG_4CH, "AAAA", PSTR("PWM RGBW")},
{TYPE_ANALOG_5CH, "AAAAA", PSTR("PWM RGB+CCT")},
Expand Down
3 changes: 2 additions & 1 deletion wled00/bus_manager.h
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Expand Up @@ -181,7 +181,8 @@ class Bus {
}
static constexpr bool hasCCT(uint8_t type) {
return type == TYPE_WS2812_2CH_X3 || type == TYPE_WS2812_WWA ||
type == TYPE_ANALOG_2CH || type == TYPE_ANALOG_5CH ||
type == TYPE_ANALOG_2CH || type == TYPE_ANALOG_2CH_HBRIDGE ||
type == TYPE_ANALOG_5CH ||
type == TYPE_FW1906 || type == TYPE_WS2805 ||
type == TYPE_SM16825;
}
Expand Down
1 change: 1 addition & 0 deletions wled00/const.h
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Expand Up @@ -325,6 +325,7 @@ static_assert(WLED_MAX_BUSSES <= 32, "WLED_MAX_BUSSES exceeds hard limit");
#define TYPE_ANALOG_MIN 41 // first usable analog type
#define TYPE_ANALOG_1CH 41 //single channel PWM. Uses value of brightest RGBW channel
#define TYPE_ANALOG_2CH 42 //analog WW + CW
#define TYPE_ANALOG_2CH_HBRIDGE 96 //analog WW + CW, relies on auto white calculation, uses H-bridge for better dimming performance at low brightness
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#define TYPE_ANALOG_3CH 43 //analog RGB
#define TYPE_ANALOG_4CH 44 //analog RGBW
#define TYPE_ANALOG_5CH 45 //analog RGB + WW + CW
Expand Down
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