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Aircoookie / WLED

Control WS2812B and many more types of digital RGB LEDs with an ESP8266 or ESP32 over WiFi!
https://kno.wled.ge
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[DXM/E131] Is channels per universe hard coded in WLED to 510? #1456

Open timdonovanuk opened 3 years ago

timdonovanuk commented 3 years ago

I've been trying to test multiple universes on one small 50 LED strip, so set up my controller to have 2 universes with each having 30 channels (i.e. 10 RGB LEDs) in XLights:

image

I then setup two lines, each with 10 LEDs. The second one starts on channel 31, i.e. universe 2:

image

However, only the first universe ever lights up. My best guess is WLED expects there always to be 510 channels on each universe? If so I will log a feature request to set channels per universe in WLED.

Thanks for reading :)

timdonovanuk commented 3 years ago

Just found this: https://wled.discourse.group/t/missing-171st-pixel-on-wled-0-10-2-with-more-than-one-e1-31-universe/853/10 so I guess that answers my question. I there any way to change the label to a feature request? :)

Aircoookie commented 3 years ago

Hi, thank you! :) Is there any usecase for a configurable universe size though? Sending more small universes instead of a few with max. size will lead to a considerable raise in network overhead, so I don't really think it would make any practical sense.

pbolduc commented 3 years ago

E1.31 uses UDP. Using a lot of small packets could lead to issues. In UDP, there is no guarantee of delivery, ordering, or duplicate protection. A UPD packet contains 20 bytes of header + data.

https://en.wikipedia.org/wiki/User_Datagram_Protocol image

E1.31 has over 100 bytes of header for on each packet.

From a network perspective this adds a lot of overhead.

From xLights side of things, is there any reason string 2 cant be on universe 1, starting on channel 31? I have installed xLights but haven't started trying to use it yet.

pbolduc commented 3 years ago

In the short term, I assume we could change this line https://github.com/Aircoookie/WLED/blob/b5232886d992090bafd719cc74643afa505c1018/wled00/e131.cpp#L3

like

#ifndef MAX_3_CH_LEDS_PER_UNIVERSE
#define MAX_3_CH_LEDS_PER_UNIVERSE 170
#endif

which would allow you to create your own custom build with the number of LEDs / universe. It is always a can of worms making things configurable, place to edit, logic to save, API logic to edit, logic to load, etc.