2-Wire Color Changing (Multiple) Protocol

[Exengprof]

I’m working to build a replacement controller for a U.S. color changing LED string.
Store brand from Lowe’s, named “Portfolio”.
Controller damaged beyond recognition!
Here is a link to what I believe is where the store gets this from.
It’s a 2-wire system.

https://www.techdesign.com/service/...xi001/color-adjustable-rgb-bulb-string-lights

for ideas.

 

[David_AVD]

Can each lamp have it's own colour or are they always all the same selected colour?

 

[TerryK]

I searched Lowe's and did not find anything similar to the TechDesign product. Portfolio' is definitely a store name brand of sorts; pretty much everything from soup to nuts in the search results. If I may be so bold, what exactly are you asking? We are all willing to help but more information of the product and your goal would be most appreciated.

 

[Exengprof]

Some answers to help ...

1. All lamps have the same color.
2. End goal: I want to set the color of the LEDs to a color of my choosing, and to have that color as a constant color. My plan is to program up a small micro to control the fixed color. I am assuming the control is a I^2C signal added to the 5V power, or some other protocol.

 

[TerryK]

Could be I2C. Most RGB seems to use SPI, although I do not know of any 2 wire SPI. You indicate the controller is trash, can you determine anything from destructive analysis? From your post it seems to be safe that one cannot further harm it. Also, any way to disassemble one of the lights to analyze its interior?

 

[Exengprof]

Between controller board from WeiXin Electronics and the LED board, the IC's labels are not visible.
Not sure if erased, removed, or not present at the build.
Attached are photos of front side/back side of board.
I guess the 4-pin IC is an opto, and the 8-pin is the smart controller.
The heat sink is for a FET which is part of the ac/dc (120Vac to 5Vac) converter.

Any insight, anyone?

 

[David_AVD]

Wow, that PSU / controller is toasted!

There would be some sort of modulation of the power source with this 2-wire system.

You'd really need a working system, an oscilloscope and a reverse engineered circuit to work it all out.

 

[TerryK]

As David mentioned, the controller appears to be a lost cause. The IMG_2927 however; is that one of the lamps? Are there components on the backside and can you follow the traces? The goal of course to reverse engineer a schematic.

The IMG_2927 photo posted 'loosely' seems to follow a typical 5 Volt WS2811 with the exception of the diode.

 

[Exengprof]

Thanks, all. The WS2811/12 is a three-wire scheme, with a data wire addressing individual pixels in the string.
The system I am trying to reverse engineer is a 2-wire system, where all LEDs are the same color.
Are these (older?) 2-wire systems controlled by the average voltage at the pins?
If a varying PWM signal is applied, will this create a different color?
I realize this can all be determined experimentally, but I am in the process of setting up my home lab!
Today, I do not have a variable power supply, nor an Arduino or microcontroller functioning to apply a different PWM signals.
Based on guidance and guessing on groups like this, I will outfit my home lab to learn / reverse engineer the controls for this string.

Is there a known control technique to change colors in a 2-wire LED string?

 

[David_AVD]

It's likely to be a DC supply with either the data superimposed (modulated). The other thought is they could be reversing the polarity in tiny slices to transfer the data. Without access to a physical unit I can't say for sure.

 

[Exengprof]

Thanks. With multiple colors, it’s not using the reverse polarity approach.
Simply for my understanding, is a variable dc voltage (via PWM) used by any 2-wire system to control color?

 

[David_AVD]

The polarity reversal I'm talking about is not to change colours, it's a possible method to send data in the LED off time.

I don't see how a PWM system could be used with multiple colours, but maybe someone's come up with something sneaky / smart.

 

[Exengprof]

Aha. I’m learning!

 

[TerryK]

While correct that the WS2811 devices are typically implemented as 3 wire, I would suggest not to assume that a clever engineer might not design it as a 2 wire. I2C devices can operate if memory serves as either 2 or 3 wire. Commands and power could be filtered similarly in a WS2811 device.

As David has indicated, it likely is some type of modulated system with the color command seen by each device (not daisy-chained as a WS2811). Similar to the old X10 system perhaps.

 

[AAH]

I'm late to this party but there was something I was wondering. The link shows a 3 part system which is what I presume something like a 31V AC square wave power supply, some smarts in some sort of inline cable and thirdly the strings of lights. Is this the same as what you've got as the burnt pic seems to have both an IR receiver and mains voltage input.
The img2927 pic shows what I presume is the bottom of the lightbulb pcb. Is there more electronics on that pcb or elsewhere or is it just a fancy looking rgb led mounted to the other side?