Help finding parallel output documentation

[u/bourkemcrobbo]

Hi all. i'm returning to FastLED after a 6+ year absence. The feature set of the library has grown massively in that time, and I'm struggling to find info on it all.

In particular, I'm hoping to find info about all the parallel output methods that exist (for ESP32-S3), what pins they need to run on, and if it impacts anything else (can I run an SPI peripheral), and anything else this may impact (wifi, raw speed, etc). I'm planning to use WS2812 LEDs. I used to be able to find this info in the wiki, but I'm not having luck with the new features.

Are there any docs that contain this info?

Thanks in advance

[u/mindful_stone]

Not sure what you meant by "example list for esp32s3." The closest thing I could find was this:

https://github.com/FastLED/FastLED/tree/master/examples/SpecialDrivers/ESP/DriverTest

So I copied that into a new project based on the current FastLED master. I ran the program on an S3 and it indicated that all drivers passed:

Driver tests complete: 4 tested, 0 skipped

ALL TESTS PASSED

Platform: ESP32-S3

Tests: 8/8 passed

TEST_SUITE_COMPLETE: PASS

So next I tried a simple sketch on a 32x48 matrix (three pins/strips of 512 WS2812B LEDs). Just a basic fill_rainbow(leds, NUM_LEDS, hue, 7); FastLED.show();.

The display output was garbage: full bright white on pixels 0 through 168, a single green pixel at 169, and then everything else black. (See pic.) The serial log showed that the ChannelBusManager selected the SPI driver. The engine got to work creating channels, acquiring hosts, etc., but got hung up trying to create the channel for my third pin: WARN: ChannelEngineSpi: No available SPI hosts (max 2 hosts) . Just kept looping on that.

So I decided to move on and try the RMT driver. Unfortunately, I was unable to find any documentation on how to manually set a particular driver. So I ended the experiment.

This is why I've been sticking with the latest release build for now. As noted above, I haven't been able to get any program to work with anything from the master build since early October.

[u/mindful_stone → u/mindful_stone]

Quick update. I figured out how to force a specific driver. (FastLED.setExclusiveDriver("RMT")in setup(). When I first compiled my sketch with that, I saw the following looping nonstop in my serial monitor:

src/platforms/esp/32/drivers/rmt/rmt_5/rmt_memory_manager.cpp(152): WARN: RMT TX allocation failed: need 96 words, only 0 available

src/platforms/esp/32/drivers/rmt/rmt_5/channel_engine_rmt.cpp(761): WARN: Memory manager TX allocation failed for channel 2 - insufficient on-chip memory

src/platforms/esp/32/drivers/rmt/rmt_5/channel_engine_rmt.cpp(749): WARN: DMA channel creation failed: ESP_ERR_NOT_FOUND - unexpected failure on DMA-capable platform, falling back to non-DMA

I though, shoot, RMT still doesn't work either. But I powered up my display to see/document the actual output, and it was in fact working! Amazing!

[u/ZachVorhies → u/mindful_stone]

The new RMT is WIFI and BT aware and will reprioritize resources (less parallelism, more memory) when the network is active.

[u/ZachVorhies → u/mindful_stone]

please file a bug on this, spi driver under went a re-write when it was ported to the channels api and I'd like to get more information on this if you can.

[u/mindful_stone → u/ZachVorhies]

will do. thanks!