Integration Log

The branch with the this driver is located at

https://github.com/FastLED/FastLED/tree/esp32s3-i2s

How to test in FastLED

clone fastled, switch to the esp32s3-i2s branch and open up the repo in VSCode

git clone https://github.com/fastled/fastled
cd fastled
git checkout esp32s3-i2s
./install # Optional, but it provides VSCode with intellisense definitions
code .  # launch vscode

VSCODE: Click the upload button (the esp32s3-i2s branch already set to i2s demo for esp32s3)

the example will now load

First Pass Results

First pass required a fix. This has been applied, see below.

FastLED compiles with IDF 5.4 so it might be newer than you are on.

Manually tested yet? No.

ESP32-S3 I2S Compilation Issues and Fixes

Issue Description

The ESP32-S3 Blink example compilation was failing with the following error:

src/third_party/yves/I2SClockLessLedDriver/src/I2SClockLessLedDriver.h:685:35: error: 'gdma_channel_alloc_config_t::<unnamed struct>' has no non-static data member named 'isr_cache_safe'

Root Cause

The newer ESP-IDF version (used by the platform) has removed the isr_cache_safe field from the gdma_channel_alloc_config_t structure. The third-party I2S driver code was still trying to initialize this deprecated field.

Fix Applied

File: src/third_party/yves/I2SClockLessLedDriver/src/I2SClockLessLedDriver.h Line: 685

Before:

gdma_channel_alloc_config_t dma_chan_config = {
    .sibling_chan = NULL,
    .direction = GDMA_CHANNEL_DIRECTION_TX,
    .flags = {
        .reserve_sibling = 0,
    .isr_cache_safe= true}};

After:

gdma_channel_alloc_config_t dma_chan_config = {
    .sibling_chan = NULL,
    .direction = GDMA_CHANNEL_DIRECTION_TX,
    .flags = {
        .reserve_sibling = 0}};

Result

After removing the unsupported isr_cache_safe field, the ESP32-S3 Blink example compiles successfully. The compilation completes with only deprecation warnings (expected with newer ESP-IDF versions) but no errors.

Additional Warnings (Non-blocking)

The following warnings remain but do not prevent compilation:

Deprecated driver/periph_ctrl.h header usage
MIN macro redefinition warning
Deprecated gdma_new_channel function (should use gdma_new_ahb_channel or gdma_new_axi_channel)
Narrowing conversion warning in ISR handler

These warnings indicate areas for future improvement but do not block current functionality.

Sep 05 '25 18:09 zackees

I've got a WS2812 matrix sitting around and an S3 so I can test this locally on that board.

I'm assuming I can do esp32dev, what about the wemos boards? Sorry if this is already in the readme.

Sep 05 '25 18:09 zackees

FYI

https://github.com/FastLED/FastLED/blob/master/src/fl/rectangular_draw_buffer.h

This could be handy to upstream

Sep 05 '25 18:09 zackees

🚨 Critical issue: Cannot reflash XIAO ESP32S3 after initial flash.

Sketch: https://github.com/FastLED/FastLED/blob/esp32s3-i2s/examples/Esp32S3I2SDemo/Esp32S3I2SDemo.h#L204
Two units tested
Two units bricked and unrecoverable

Attempts to recover:

Hold down the reset button until Looking for upload port... appears, then release
Hold down the reset & boot button until Looking for upload port... appears, then release

Bricked Devices

Windows gives the error message mentioned above. When I plug/unplug devices from my Windows box then windows is will indicate that the device is not functioning correctly after about 6 seconds with the error message above.

⚠️ Stdout not functioning

The second attempt recompiled the test program https://github.com/FastLED/FastLED/blob/d85e74c921ce12e6bf1ff47eaf92a1698bb036d7/examples/Esp32S3I2SDemo/Esp32S3I2SDemo.h#L204 with a print test using the EVERY_N_MILLISECONDS(1000) macro

Result: Could not connect to stdout port.

 *  Executing task: C:\Users\niteris\.platformio\penv\Scripts\platformio.exe run --target upload 

Processing dev (board: seeed_xiao_esp32s3; platform: https://github.com/pioarduino/platform-espressif32/releases/download/54.03.20/platform-espressif32.zip; framework: arduino)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Verbose mode can be enabled via `-v, --verbose` option
CCACHE is not available. Skipping CCACHE configuration.
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/seeed_xiao_esp32s3.html
PLATFORM: Espressif 32 (54.3.20) > Seeed Studio XIAO ESP32S3
HARDWARE: ESP32S3 240MHz, 320KB RAM, 8MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-builtin, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES:
 - framework-arduinoespressif32 @ 3.2.0
 - framework-arduinoespressif32-libs @ 5.4.0+sha.2f7dcd862a
 - tool-clangtidy @ 1.190100.0 (19.1.0)
 - tool-esptoolpy @ 4.8.9
 - tool-mkfatfs @ 2.0.1
 - tool-mklittlefs @ 3.2.0
 - tool-mkspiffs @ 2.230.0 (2.30)
 - tool-openocd-esp32 @ 2.1100.20220706 (11.0)
 - tool-riscv32-esp-elf-gdb @ 14.2.0+20240403
 - tool-xtensa-esp-elf-gdb @ 14.2.0+20240403
 - toolchain-riscv32-esp @ 14.2.0+20241119
 - toolchain-xtensa-esp-elf @ 14.2.0+20241119
Converting dev.ino
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 42 compatible libraries
Scanning dependencies...
Dependency Graph
|-- FastLED @ 3.10.2
Building in debug mode
Compiling .pio\build\dev\src\dev.ino.cpp.o
Retrieving maximum program size .pio\build\dev\firmware.elf
Checking size .pio\build\dev\firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [=         ]  11.0% (used 36008 bytes from 327680 bytes)
Flash: [=         ]  11.4% (used 358974 bytes from 3145728 bytes)
Configuring upload protocol...
AVAILABLE: cmsis-dap, esp-bridge, esp-builtin, esp-prog, espota, esptool, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa
CURRENT: upload_protocol = esptool
Looking for upload port...
Auto-detected: COM4
Uploading .pio\build\dev\firmware.bin
esptool.py v4.8.9
Serial port COM4

A fatal error occurred: Could not open COM4, the port is busy or doesn't exist.
(could not open port 'COM4': OSError(22, 'The semaphore timeout period has expired.', None, 121))

Sep 06 '25 22:09 zackees


#ifdef ESP32

/// The Yves ESP32_S3 I2S driver is a driver that uses the I2S peripheral on the ESP32-S3 to drive leds.
/// Originally from: https://github.com/hpwit/I2SClockLessLedDriveresp32s3
///
///
/// This is an advanced driver. It has certain ramifications.
///   - Once flashed, the ESP32-S3 might NOT want to be reprogrammed again. To get around
///     this hold the reset button and release when the flash tool is looking for an
///     an upload port.
///   - Put a delay in the setup function. This is to make it easier to flash the device during developement.
///   - Serial output will mess up the DMA controller. I'm not sure why this is happening
///     but just be aware of it. If your device suddenly stops working, remove the printfs and see if that fixes the problem.
///
/// Is RGBW supported? Yes.
///
/// Is Overclocking supported? Yes. Use this to bend the timeings to support other WS281X variants. Fun fact, just overclock the
/// chipset until the LED starts working.
///
/// What about the new WS2812-5VB leds? Yes, they have 250us timing.
///
/// Why use this?
/// Raw YVes driver needs a perfect parallel rectacngle buffer for operation. In this code we've provided FastLED
/// type bindings.
///
// ArduinoIDE
//  Should already be enabled.
//
// PLATFORMIO BUILD FLAGS:
// Define your platformio.ini like so:
//
// PlatformIO
// [env:esp32s3]
// platform = https://github.com/pioarduino/platform-espressif32/releases/download/54.03.20/platform-espressif32.zip
// framework = arduino
// board = seeed_xiao_esp32s3


#define FASTLED_USES_ESP32S3_I2S  // Must define this before including FastLED.h

#include <Arduino.h>
#include "FastLED.h"
#include "fl/assert.h"


#define NUMSTRIPS 16
#define NUM_LEDS_PER_STRIP 256
#define NUM_LEDS (NUM_LEDS_PER_STRIP * NUMSTRIPS)

// Note that you can use less strips than this.

#define EXAMPLE_PIN_NUM_DATA0 19  // B0
#define EXAMPLE_PIN_NUM_DATA1 45  // B1
#define EXAMPLE_PIN_NUM_DATA2 21  // B2
#define EXAMPLE_PIN_NUM_DATA3 6   // B3
#define EXAMPLE_PIN_NUM_DATA4 7   // B4
#define EXAMPLE_PIN_NUM_DATA5 8   // G0
#define EXAMPLE_PIN_NUM_DATA6 9   // G1
#define EXAMPLE_PIN_NUM_DATA7 10  // G2
#define EXAMPLE_PIN_NUM_DATA8 11  // G3
#define EXAMPLE_PIN_NUM_DATA9 12  // G4
#define EXAMPLE_PIN_NUM_DATA10 13 // G5
#define EXAMPLE_PIN_NUM_DATA11 14 // R0
#define EXAMPLE_PIN_NUM_DATA12 15 // R1
#define EXAMPLE_PIN_NUM_DATA13 16 // R2
#define EXAMPLE_PIN_NUM_DATA14 17 // R3
#define EXAMPLE_PIN_NUM_DATA15 18 // R4


// Users say you can use a lot less strips. Experiment around and find out!
// Please comment at reddit.com/r/fastled and let us know if you have problems.
// Or send us a picture of your Triumps!
int PINS[] = {
    EXAMPLE_PIN_NUM_DATA0,
    EXAMPLE_PIN_NUM_DATA1,
    EXAMPLE_PIN_NUM_DATA2,
    EXAMPLE_PIN_NUM_DATA3,
    EXAMPLE_PIN_NUM_DATA4,
    EXAMPLE_PIN_NUM_DATA5,
    EXAMPLE_PIN_NUM_DATA6,
    EXAMPLE_PIN_NUM_DATA7,
    EXAMPLE_PIN_NUM_DATA8,
    EXAMPLE_PIN_NUM_DATA9,
    EXAMPLE_PIN_NUM_DATA10,
    EXAMPLE_PIN_NUM_DATA11,
    EXAMPLE_PIN_NUM_DATA12,
    EXAMPLE_PIN_NUM_DATA13,
    EXAMPLE_PIN_NUM_DATA14,
    EXAMPLE_PIN_NUM_DATA15
};

CRGB leds[NUM_LEDS];

void setup_i2s() {
    // Note, in this case we are using contingious memory for the leds. But this is not required.
    // Each strip can be a different size and the FastLED api will upscale the smaller strips to the largest strip.
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA0, GRB>(
        leds + (0 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA1, GRB>(
        leds + (1 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA2, GRB>(
        leds + (2 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA3, GRB>(
        leds + (3 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA4, GRB>(
        leds + (4 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA5, GRB>(
        leds + (5 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA6, GRB>(
        leds + (6 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA7, GRB>(
        leds + (7 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA8, GRB>(
        leds + (8 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA9, GRB>(
        leds + (9 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA10, GRB>(
        leds + (10 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA11, GRB>(
        leds + (11 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA12, GRB>(
        leds + (12 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA13, GRB>(
        leds + (13 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA14, GRB>(
        leds + (14 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
    FastLED.addLeds<WS2812, EXAMPLE_PIN_NUM_DATA15, GRB>(
        leds + (15 * NUM_LEDS_PER_STRIP), NUM_LEDS_PER_STRIP
    );
}



void setup() {
    // put your setup code here, to run once:
    Serial.begin(57600);

    // This is used so that you can see if PSRAM is enabled. If not, we will crash in setup() or in loop().
    log_d("Total heap: %d", ESP.getHeapSize());
    log_d("Free heap: %d", ESP.getFreeHeap());
    log_d("Total PSRAM: %d", ESP.getPsramSize());  // If this prints out 0, then PSRAM is not enabled.
    log_d("Free PSRAM: %d", ESP.getFreePsram());

    log_d("waiting 6 seconds before startup");
    delay(6000);  // The long reset time here is to make it easier to flash the device during the development process.

    setup_i2s();
    FastLED.setBrightness(16);
   
}

void fill_rainbow(CRGB* all_leds) {
    static int s_offset = 0;
    for (int j = 0; j < NUMSTRIPS; j++) {
        for (int i = 0; i < NUM_LEDS_PER_STRIP; i++) {
            int idx = (i + s_offset) % NUM_LEDS_PER_STRIP + NUM_LEDS_PER_STRIP * j;
            all_leds[idx] = CHSV(i, 255, 255);
        }
    }
    s_offset++;
}

void loop() {
    fill_rainbow(leds);
    FastLED.show();
    
}

#else  // ESP32

// Non-ESP32 platform - provide minimal example for compilation testing
#include "FastLED.h"

#define NUM_LEDS 16
#define DATA_PIN 3

CRGB leds[NUM_LEDS];

void setup() {
    FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);
}

void loop() {
    fill_rainbow(leds, NUM_LEDS, 0, 7);
    FastLED.show();
    delay(50);
    EVERY_N_MILLISECONDS(1000) {
        Serial.println("Stdout works.");
    }
}

#endif  // ESP32

Sep 06 '25 22:09 zackees

Integration log for FastLED

Integration Log

How to test in FastLED

First Pass Results

ESP32-S3 I2S Compilation Issues and Fixes

Issue Description

Root Cause

Fix Applied

Result

Additional Warnings (Non-blocking)

Attempts to recover:

Bricked Devices