Tail of the 48 invisible pixels. New Copper Dipped Addressed Pixels it seems

[jamestutton]

A very odd issue.

Have some of the "ws2812b" dipped copper wire style LEDs. They have been cut off a larger strip off 100. In total there are 40 pixels on the strip. Original set was 100 LEDs.

Was having issues getting them working with both wled and esphome untill I set the pixel count to a a number greater than there length. Then realised the odd issue. The first pixel appears to be the 49th pixel. Ie the first 48 addresses do nothing.

Even hooked them up to a larger strip of normal 12mm ws2812b 1-150 normal ws2812s. Pixels 150-190 should be these. But no. Have to set the chain as 238. LEDs 1-150 light normally 151-198 don't exist so nothing happens 199 onwards light this strip first led onwards

So 48 addresses get skipped then these LEDs start again from 199 onwards.

Hopefully this is clear and someone seen this before and has a clue?

Currently these LEDs terminate on last led of the strip so not able to see what happens of add more to end of the chain. But may cut last one off just to see.

[ChayD]

Thanks! I found this on Aliexpress: https://ww.aliexpress.com/item/1005003070133485.html

Same remote control. And it came with a high resolution photo.

Ah! Nice find!

[ChayD]

The two-wire rope light LEDs finally arrived from Wish, it doesn't look like they're addressable in the same sense as, say a WS2811, they're more like a slightly smarter version of those devices where they're practically PWM, but rather than sending the pwm signal in parallel you do it serially, like [SOF][R][G][B] where [SOF] (start of frame) would be a low level for, say, two bit periods, followed by three inverse bits to tell the devices which diodes to light, (e.g. 011 being red, 101 green and 110 blue etc). I think these particular ones have four or more bits after [SOF] as a sort of address. I'm just guessing here as I've not looked deeply into the waveforms. Needless to say, these would be harder to drive than regular addressable LEDs and need a lot of cpu intensive bit banging to get them to do anything cool. I'll still try and figure them out just for funsies though :)

[cpldcpu]

I noticed that there seem to be a lot of christmas decoration that allow somewhat individualized control with only two wires:

For example this one: https://www.aliexpress.com/item/1005001921905932.html

Since these are low-voltage strings, some kind of electronic is needed anyways as a constant current supply for the LEDs. Just using resistors would cause visible droop. So I presume they just added a minimum of control.

[prabbit237]

cpldcpu commented 3 days ago I noticed that there seem to be a lot of christmas decoration that allow somewhat individualized control with only two wires:

Based on the remote, I think those ones are a set color (either all white or multi-colored but not changing colors) so all they'd need is to PWM them and the whole string flashes. There IS, of course, 1-Wire communications systems but it seems like anything drawing all that much current wouldn't be able to run too much bandwidth/info across the two wires at the same time.

[cpldcpu]

The two-wire rope light LEDs finally arrived from Wish, it doesn't look like they're addressable i

Mine from above also arrived. Seems to use the same scheme to control. Quite curious already, I will dig a bit into this.

Based on the remote, I think those ones are a set color (either all white or multi-colored but not changing colors) so all they'd need is to PWM them and the whole string flashes. There IS, of course, 1-Wire communications systems but it seems like anything drawing all that much current wouldn't be able to run too much bandwidth/info across the two wires at the same time.

The LEDs look exactly like the controllable ones in the other chain that already arrived. Well, I also ordered the one I linked above, so we will see in a few weeks.

[cpldcpu]

I completed my analysis of the 2-wire LEDs, will write something up. It's a really clever concept, but also quite limited. I don't think that it is too good of a fit to WLED. But who knows, these devices may evolve and it seems that there are already many products on the market using them.

@ChayD it appears that at least my LED are simply using a linear count of pulses in the protocol, no binary encoding.

[cpldcpu]

Very interesting video on the assembly process of these strings that was posted by Harald on µC.net:

https://www.youtube.com/watch?v=wCKlCUBsaT4

Amazing amount of hand assembly. It's also clear that they cannot really deal with segmented datalines. That's why they went to great length to connect everythin in parallel.

[cpldcpu]

I had some fun with these LEDs, some detailed write-up here:

https://cpldcpu.wordpress.com/2022/01/23/controlling-rgb-leds-with-only-the-powerlines-anatomy-of-a-christmas-light-string/

Unfortunately not really suited for WLED, unless one only want to implement very basic effects. Could be of interest to integrated into the same ecosystem, though.

[ChayD]

That is some comprehensive write-up - nice work!

[cpldcpu]

The cheaper string from above was a "dumb" one indeed. But it still had some surprises: All LEDs are based on blue emitting chips and are phosphor converted. This helps to circumvent the issue of connecting LEDs with different forward voltage in parallel. Also, the light quality is better imo.

Summary here: https://cpldcpu.wordpress.com/2022/01/29/analyzing-another-multicolor-string-light-with-unusual-leds/

[PinheadBE]

Hi, I'm having a hard time to find a reseller in Europe. Due to taxes and other costs, it has become expensive to buy from AliExpress..... Does anyone have a website in Europe for this ?

[prabbit237]

Due to taxes and other costs, it has become expensive to buy from AliExpress.....

Just as an off-topic side-note, I once did a search to see what was the cheapest thing I could get from Aliexpress back around 1PT (using the Pre-Trump year dating system.) Chinese companies used to get really cheap postage rates here in the US (some sort of subsidies or such were in place) and you could get all kinds of things for around $1 and free shipping (at the time, just sending a letter across town was $0.49 and another $0.20/ounce after the first one. Shipping something in a plastic bag would probably have been more due to it not being "machinable" with the automated sorting.)

I found a small LED bulb for use in a car's instrument cluster to light up the dash. Price with FREE shipping was either $0.11 or $0.13 (forgot which.) So I ordered a single bulb and, sure enough, my "under $0.15 bulb" arrived about a month later.

[honnet]

Hi @cpldcpu, @ChayD, @prabbit237, @PinheadBE and anyone interested!

Would you happen to know how to find this 1-wire LED alone? (or any other)

Thanks for sharing this great discovery!!

[cpldcpu]

@honnet Unfortunately, no idea.

[cpldcpu]

There are now bluetooth versions of the "copper dipped addressed pixels" available:

They use a BLE SOC, SWD fully exposed:

Comes with 256kb of flash:

https://www.lenzetech.com/stProduct/ST17H66

SDK is here:

https://github.com/17HXX/BLE5_ST17H66

Anyone up to porting WLED? ;)

[darkmattercoder]

I have a few of those addressable fairy strings from above here. I could kinda drive them via wled, when using odd start and length numbers. However somewhere from 0.13-4 to 0.13-6 there seems to be a change where you cannot adjust the start number anymore without adding "dead" segments. First segment has to start at index zero apparently.

[darkmattercoder]

Okay, they have added a checkbox for this apparently.....

[shupershuff]

Ugh, seems I've fallen into this trap with these, https://www.aliexpress.com/item/1005001917228863.html. Glad this thread exists, thought I was going mad.

[blazoncek]

Closing this issue as it may be linked to pre-addressed LEDs (those with fixed addresses) and WLED support for adding multiple "skip 1st pixel" has been added. If you feel otherwise please request re-opening.