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(0.15.x backport) bus_wrapper: Use parallel I2S first when enabled #4766

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(0.15.x backport) bus_wrapper: Use parallel I2S first when enabled #4766

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cfa8b73
bus_wrapper: Use parallel I2S first when enabled
willmmiles Jul 9, 2025
e428e80
bus_wrapper: Update comments to reflect RMT usage
willmmiles Jul 9, 2025
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19 changes: 14 additions & 5 deletions wled00/bus_wrapper.h
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Original file line number Diff line number Diff line change
Expand Up @@ -469,12 +469,20 @@ class PolyBus {
}

static void* create(uint8_t busType, uint8_t* pins, uint16_t len, uint8_t channel) {
#if defined(ARDUINO_ARCH_ESP32) && !(defined(CONFIG_IDF_TARGET_ESP32S2) || defined(CONFIG_IDF_TARGET_ESP32S3) || defined(CONFIG_IDF_TARGET_ESP32C3))
// NOTE: "channel" is only used on ESP32 (and its variants) for RMT channel allocation

#if defined(ARDUINO_ARCH_ESP32) && !defined(CONFIG_IDF_TARGET_ESP32C3)
if (_useParallelI2S && (channel >= 8)) {
// Parallel I2S channels are to be used first, so subtract 8 to get the RMT channel number
channel -= 8;
}
#endif

#if defined(ARDUINO_ARCH_ESP32) && !(defined(CONFIG_IDF_TARGET_ESP32S2) || defined(CONFIG_IDF_TARGET_ESP32S3) || defined(CONFIG_IDF_TARGET_ESP32C3))
// since 0.15.0-b3 I2S1 is favoured for classic ESP32 and moved to position 0 (channel 0) so we need to subtract 1 for correct RMT allocation
if (!_useParallelI2S && channel > 0) channel--; // accommodate I2S1 which is used as 1st bus on classic ESP32
// if user selected parallel I2S, RMT is used 1st (8 channels) followed by parallel I2S (8 channels)
#endif

void* busPtr = nullptr;
switch (busType) {
case I_NONE: break;
Expand Down Expand Up @@ -1428,7 +1436,8 @@ class PolyBus {
// ESP32-S2 only has 4 RMT channels
if (_useParallelI2S) {
if (num > 11) return I_NONE;
if (num > 3) offset = 1; // use x8 parallel I2S0 channels (use last to allow Audioreactive)
if (num < 8) offset = 1; // use x8 parallel I2S0 channels followed by RMT
// Note: conflicts with AudioReactive if enabled
} else {
if (num > 4) return I_NONE;
if (num > 3) offset = 1; // only one I2S0 (use last to allow Audioreactive)
Expand All @@ -1441,15 +1450,15 @@ class PolyBus {
// On ESP32-S3 only the first 4 RMT channels are usable for transmitting
if (_useParallelI2S) {
if (num > 11) return I_NONE;
if (num > 3) offset = 1; // use x8 parallel I2S LCD channels
if (num < 8) offset = 1; // use x8 parallel I2S LCD channels, followed by RMT
} else {
if (num > 3) return I_NONE; // do not use single I2S (as it is not supported)
}
#else
// standard ESP32 has 8 RMT and x1/x8 I2S1 channels
if (_useParallelI2S) {
if (num > 15) return I_NONE;
if (num > 7) offset = 1; // 8 RMT followed by 8 I2S
if (num < 8) offset = 1; // 8 I2S followed by 8 RMT
} else {
if (num > 9) return I_NONE;
if (num == 0) offset = 1; // prefer I2S1 for 1st bus (less flickering but more RAM needed)
Expand Down