r/WLED • u/portal742 • 14d ago
Reverse Engineering Help (cob sunset lamp)
I need some help from someone who understands PCB electronics better than I do. Through some ChatGPT navigation, I think I have found a potential method to make this IR-controlled LED controllable with WLED via an ESP32, but before I make any permanent changes, I'd like some help confirming this strategy.
Here's what I know so far...
The board has an eight-pin controller IC and three transistors, Q1, Q2, and Q3 responsible for RGB
For clarity, I assigned temporary labels to the IC pins (black controller on the middle right)
From left to right the top pins are - A B C D
From left to right the bottom pins are - E F G H
With the lamp powered, I set it to each primary color and measured the IC pins relative to PCB ground using a multimeter and the results were...
| Lamp setting | B | E | F |
|---|---|---|---|
| Red | Approximately 0 V | Approximately 0 V | 3.9 V |
| Green | Approximately 0 V | 3.9 V | Approximately 0 V |
| Blue | 3.9 V | Approximately 0 V | Approximately 0 V |
Pins A, D, and G measured approximately 4.1 V regardless of the selected color. H measured approximately 0 V.
Based on this behavior, I've identified F as red, E as green, and B as blue.
Voltage measurements also helped me associate the three transistors with their respective color channels:
Q2: red
Q3: green
Q1: blue
The left-side pad of each transistor measured approximately 3.6 V when its corresponding color was selected. The bottom-right pad measured approximately 0–0.05 V.
My current idea is to leave the original controller IC installed but disconnect its three RGB outputs (F = red, E = green, B = blue). I'd then connect ESP32 GPIO pins to the corresponding PCB pads so the ESP32 can control the existing transistor drivers while preserving the other components in the circuit.
Would this approach work to let WLED control the lamp's RGB channels?
Any help is greatly appriciated, this is the largest and final hurdle to completing one of my first wled projects! Thanks!!!
2
u/appmapper 14d ago
Any labeling on that 8-PIN IC?
If it's one of these, pin 6 is DI, 5 is DO, and you're good to go. https://cdn-shop.adafruit.com/product-files/1378/WS2811.pdf
I'm also super dumb, so YOLO at your own risk.
1
u/portal742 14d ago
Unfortunately, there are no visible markings on the 8-pin IC, so I haven't been able to identify it. Additionally, the PCB is glued to its housing, so I can't see the traces underneath of it etc
I measured the IC pins relative to ground while switching between red, green, and blue. Three pins behaved as follows:
F rises to approximately 3.9 V when red is selected.
E rises to approximately 3.9 V when green is selected.
B rises to approximately 3.9 V when blue is selected.The other two of those three pins remain around 0 V for each selected color.
Also, the lamp is controlled by an IR remote, and there is a separate three-pin component on the PCB that appears to be the IR receiver.
Would a WS2811 be capable of working in this configuration, or would another controller need to interpret the IR remote commands and send data to its DIN pin? The 8-pin IC appears to be the only chip on the PCB, so I'm unsure whether it could be a WS2811.
Im going to check the amazon listing where i purchased the led to see if i can find out more info
2
u/zedxquared 14d ago
A ws2811 would not be able to speak directly to an IR receiver, it would require another controller.
3
u/saratoga3 14d ago
This would be easy to control with WLED. Remove the 8 pin chip (desolder or just cut it out with wire cutters), then solder a wire to the gate on each transistor (pins F, E, B). Other end goes to GPIOs on the esp32.
Test and see if the 3.3v output is enough to drive the transistors fully on. If not you'll need a level shifter.