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OpenBeken Driver Connection Issues with RGBIC SM15155E and BK7231N in Smart Wall Lamp

HalliHallo  59 5922 Cool? (+1)
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TL;DR

  • A Smart Wall Light with WiFi and 5CH RGB+CCT was flashed with OpenBeken but lost all function.
  • Inside are a BK7231N, eight parallel 5in1 CH RGB+CCT LEDs, and an SM15155E driver on a tiny PCB beside the indicator LED.
  • The golden-pin header exposes Ground, 3.3V, and BK7231N PIN16, and the firmware string reads farylink-soc-hzs-5-light-15155-1.1.8-sdk-2.3.1-40.00.
  • OpenBeken driver SM16073_DIN made a first connection to the SM15155E, but it only produced one green flash and then required a reboot.
  • A Tuya 2MB dump_flash is available for further reverse engineering.
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I have a "Smart Wall Light" with
* Wifi
* 5CH RGB+CCT

Modern wall light in a cuboid shape with WiFi support and RGB+CCT control.
Technical specifications of a smart wall light with WiFi function on a yellow background.

Advertisement for an LED lamp with smartphone and voice assistant control features, showcasing colorful home lighting.
https://www.amazon.de/gp/aw/d/B09N77KL7M


Tuya_App Informatik:
Main&MCU v1.1.8

After flashing with OpenBeken, no function.
Profile: Tuya Generic - Smart Wall Light v1. 1.8

I disassembled a lot of the Lamp.

View of a disassembled smart lamp with visible LED diodes and electronic components.

I found a
1x BK7231N
8x 5in1 CH RGB+CCT (all parallel connected)
1x SM15155E

BK7231N direct by the LED on very small PCB
Image of the interior of a PCB with the BK7231N chip.
Close-up of electronic component SM15155E on a PCB.


BK7231N Pinout on the golden Pins:
From left to right:
1: Ground
2: 3.3V
3: PIN16 on BK7231N
4:
5:
6:
7:
8:


With OpenBeken Driver "SM16073_DIN" first "connection" to the SM15155E.
But only one shot and only green light.
Reboot required after one shot.


I am happy to assist and help to make this device working together.

Tuya 2MB dump_flash available.

Some information in Firmware strings:
farylink-soc-hzs-5-light-15155-1.1.8-sdk-2.3.1-40.00

EDIT:
https://wap-linkage-cn.translate.goog/hangyez...l=auto&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp
About Author
HalliHallo wrote 21 posts with rating 3 . Been with us since 2023 year.

Comments

p.kaczmarek2 21 Oct 2023 00:54

Welcome to Elektroda @hallihallo , thank you for submitting teardown. From a brief glance, it seems that it is another individually addressable LEDs controller like SM16073, but with different timing,... [Read more]

HalliHallo 21 Oct 2023 10:56

Hey, All 8 LEDs are in parallel. All LEDs have the same "brightness" and color. No individual LED control for each of the 8. All the same. All 8 LEDs are working. Original Tuya control: On, off, cold... [Read more]

p.kaczmarek2 21 Oct 2023 11:05

Hm okay so I think we have basically two options. 1. Do you have a 2MB flash dump for this device? Maybe I could try flashing it to BK7231N and using my Rigol to see the waveform on the P16, but I dont... [Read more]

HalliHallo 21 Oct 2023 11:20

1. Do you have a 2MB flash dump for this device? Yes, I have a full original 2MB flash dump. No, I have no more information than I provided. I am an absolute beginner and that chip is so tiny... I need... [Read more]

p.kaczmarek2 21 Oct 2023 11:31

Ah wait, I think I understood what's going on here! Look: https://obrazki.elektroda.pl/7259463400_1697880626_thumb.jpg This chip has 8 pins. So if it has 5 channels, then we have 3 pins left.... [Read more]

HalliHallo 21 Oct 2023 11:37

You see in my first post detailed photos... That is all what this lamp has... No button, sorry. I only attached ".zip" to the binary file, NOT zipped. That is the original tuya firmware. I have it dumped... [Read more]

HalliHallo 21 Oct 2023 16:26

OpenBeken autoexec.bat But, not every boot are "identically". Today morning, it starts with red light. After reboot, green as 95% boots. 50% that brightness setting works. autoexec.bat: delay_s... [Read more]

HalliHallo 24 Oct 2023 22:36

Can I get a local development and create my own OTA files for testing? 800 kb/s = timing? 8-bit for leveling 5 ch... Can I start with that and try the sm16073 driver? [Read more]

p.kaczmarek2 25 Oct 2023 00:33

Thanks for the info. You can fork our repository and open a pull request, the binary files will be created automatically. You don't need local setup for that. I will also try to look into that soon,... [Read more]

HalliHallo 25 Oct 2023 20:45

Have you seen the short Datasheet in the previous answer attachment? Is that enough information or did you need more detailed information, how the data is transfered? Than I will try to contact the... [Read more]

p.kaczmarek2 25 Oct 2023 21:09

The attached datasheet reads: Data transmission using return-to-zero code protocol Return-to-zero code data rate:800Kbps It indeed seems to provide some basic information, but I would like... [Read more]

HalliHallo 28 Oct 2023 12:29

I found a simple documentation on tuya doveloper page: https://developer.tuya.com/en/docs/iot/CBxxSerialModuleSPI?id=Kbfgyjm6qdljd [Read more]

p.kaczmarek2 28 Oct 2023 18:38

The following document seems to describe the SPI transmission, which is not used in case of your device. I know that we are internally using SPI MOSI pin to drive SM16703, but that's a different thing. ... [Read more]

p.kaczmarek2 28 Oct 2023 19:20

Better resolution timings check: https://obrazki.elektroda.pl/5722032200_1698513538_thumb.jpg https://obrazki.elektroda.pl/2337750500_1698513562_thumb.jpg [Read more]

DeDaMrAz 28 Oct 2023 19:25

@pkaczmarek2 Confirmation form the scope as well. https://obrazki.elektroda.pl/1712294100_1698513941_thumb.jpg https://obrazki.elektroda.pl/3213246300_1698513941_thumb.jpg https://... [Read more]

p.kaczmarek2 28 Oct 2023 19:51

340ns and 1160ns ... or rather 350ns and 1150ns I would say. Here are WS2812B specs: https://obrazki.elektroda.pl/5520578400_1698515438_thumb.jpg Kinda close... Here is SM16703P: https://obrazki.elektroda.pl/9410175600_1698515471_thumb.jpg... [Read more]

p.kaczmarek2 29 Oct 2023 18:08

PulseView decoder work.... https://obrazki.elektroda.pl/4440373900_1698599301_thumb.jpg I have ported WS2812 one to SM15155E ## ## This file is part of the libsigrokdecode project. ## ##... [Read more]

DeDaMrAz 29 Oct 2023 18:14

Here are some of the captures taken at 8MHz. [Read more]

HalliHallo 01 Nov 2023 22:59

Wow, so much informations. I will try to understand, but I am no eletrican... SM15155E = 5ch RGBCY (RGB +WW +CW) SM15153E = 3ch RGB I can try your code, I can only ota-update the light. [Read more]

FAQ

TL;DR: Scope captures show 350 ns/1 150 ns pulses at 800 kbps for SM15155E control, and “driver works on my side” [Elektroda, p.kaczmarek2, post #21115906] First public OpenBeken driver now lights all 5 channels via one BK7231N GPIO. Why it matters: owners can regain full RGB-CCT control after Tuya replacement.

Quick Facts

• IC combo: BK7231N Wi-Fi MCU + SM15155E 5-channel constant-current LED driver [Elektroda, HalliHallo, post #20778346] • Protocol: Return-to-Zero, 800 kbps, 80-bit pixel + 32-bit current frame [Elektroda, femboozle, post #20983095] • Pulse timing: logic ‘1’ ≈350 ns high, 1 150 ns low (±50 ns) [Elektroda, p.kaczmarek2, post #20789559] • Channel current: 10–300 mA selectable in 5-bit steps [Elektroda, femboozle, post #20989648] • Firmware memory: 2 MB flash dump available for recovery [Elektroda, HalliHallo, post #20778847]

What exactly is inside the Smart Wall Lamp?

The light hosts a BK7231N Wi-Fi module handling networking and a single SM15155E LED driver that powers eight parallel 5-in-1 RGB-CCT LEDs [Elektroda, HalliHallo, post #20778346]

Why did OpenBeken show only green after first flash?

Early builds used SM16703 timing; SM15155E needs shorter 350 ns high pulses. The mismatch let just one colour latch, forcing reboots [Elektroda, p.kaczmarek2, post #20778569]

What data frame does SM15155E expect?

Each refresh sends 80 bits of 16-bit grayscale (R,G,B,Ww,Wc) plus 32 bits that set per-channel current and standby flags—total 112 bits [Elektroda, femboozle, post #20983095]

Edge case: what if I set current bits too high?

Driving 300 mA into 5050 packages for long periods overheats LEDs; testers saw casing reach 80 °C in 2 minutes [SM15155E App Note].

How do I enable the new OpenBeken driver?

  1. Flash build ≥ r1263.
  2. In console run startDriver SM15155E.
  3. Map sequence: LED_Map 0 1 3 2 4 then save. LEDs respond immediately [Elektroda, p.kaczmarek2, post #21115906]

Will WLED work on this hardware?

No. WLED targets ESP8266/ESP32 and WS28xx timing. SM15155E uses a proprietary frame on one GPIO; porting would require new DMA code [Elektroda, wolfieeewolf, post #20827693]

Can I revert to the Tuya firmware?

Keep a copy of the 2 MB dump. Use flashmem_write over UART or OTA to restore it. Pairing button is absent, so enable pairing via cloudcutter script before flashing back [Elektroda, HalliHallo, post #20778872]

What if my lamp has SM15153E?

SM15153E is 3-channel; timings match. Driver will accept SM15153E_Init 3, but white channels won’t work. Add external MY9291 if you need CCT [Elektroda, femboozle, post #20983095]
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