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Flashing 3Stone 100W Smart Light Bulb [BP5758D + WB2L] - Using BK7231T Chip, Alexa Compatible

andy212332 2535 9

TL;DR

  • Flashing guide for the 3Stone 100W Equivalent WiFi LED color-changing bulb, using BP5758D + WB2L hardware and a BK7231T chip, with Alexa compatibility.
  • The LED board comes out from the small end with a long screwdriver, and the chip pins are reachable from the back, so desoldering is unnecessary.
  • The bulb is a [2023 Upgraded] Smart Light Bulbs pack of 4, model B07HR8GT12, rated 100W equivalent, 10W, 2700K-6500K, RGBCW, and 2.4Ghz only.
  • A 3.3v serial connection provided enough power for flashing, so no separate power supply was needed.
  • Warm and cool LED pins had to be inverted to make the setup work correctly.
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  • Close-up of 3Stone LED bulb showing technical specifications.
    This is a firmware flashing guide for: [2023 Upgraded] Smart Light Bulbs (Pack of 4), 3Stone 100W Equivalent WiFi LED Color Changing Bulb Dimmable 2700K-6500K RGBCW, Works with Alexa, Google Home 2.4Ghz Only, A21 10W E26 Tunable White No Hub

    Bought from: https://www.amazon.com/gp/product/B07HR8GT12
    Screenshots:
    Image of product 3Stone Smart Light Bulbs (4 pack), 100W equivalent, color-changing, dimmable.
    Product ASIN B07HR8GT12

    Followed the instructions here with some minor changes: https://www.youtube.com/watch?v=2e1SUQNMrgY


    - Removed the LED board by using a long screwdriver and pushing down from the small end of the bulb. Trying to pry from the top will just break the plastic.
    - No need to desolder the chip, you can get to the pins from the back.
    - Did not have to use a separate power supply, 3.3v from the serial worked fine.
    - Had to invert the Warm/Cool LED pins,


    Screenshot of LED driver tools interface.


    Code: JSON
    Log in, to see the code



    Close-up of 3Stone LED bulb showing technical specifications.
    Close-up of an electronic module labeled WB2L.
    Close-up of the LED layout on a light bulb's printed circuit board.
    LED board with multicolored diodes and BP5758 chip.
    Screwdriver inserted inside the case of a smart light bulb.
    Image of the electronic circuit for flashing the firmware of a 3Stone LED bulb.
    Circuit board with wires soldered for firmware flashing of the integrated circuit.

    Cool? Ranking DIY
    About Author
    andy212332
    Level 3  
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    andy212332 wrote 5 posts with rating 1. Been with us since 2023 year.
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  • #2 20778694
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12435
    You were very lucky that the programming pads were accessible just by a fraction of the board. It really makes the job easier, but I still really like desoldering WB2L just like on the video you linked.

    Now you can buy multiple those bulbs and use them in, for example, DGR:
    https://www.youtube.com/watch?v=e1xcq3OUR5M&ab_channel=Elektrodacom

    Anyway, thank you for posting the guide! I have slightly modified your topic, but in general, it's informative and helpful. Feel free to post any other device teardowns you can.
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  • #3 20780843
    andy212332
    Level 3  
    Posts: 5
    Rate: 1

    Do you know if it's possible to make the bulbs brighter? I think that the bulbs were much brighter when they had the original Tuya firmware.
  • #4 20780854
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12435
    Yes, it is possible to make this kind of bulb brighter, you need to adjust the current limit of BP5758D. This can be done via console command, namely BP5758D_Current
    Screenshot of documentation regarding the BP5758D_Current command and its function.
    However, following command must be used with extreme caution because you may overcurrent your LEDs. That may damage them or at least shorten their lifespan significantly.

    Added after 16 [seconds]:

    Please refer to our docs for a full commands list:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md
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  • #5 20780857
    andy212332
    Level 3  
    Posts: 5
    Rate: 1

    Thanks, I'll check it out.

    Added after 13 [minutes]:

    p.kaczmarek2 wrote:
    Yes, it is possible to make this kind of bulb brighter, you need to adjust the current limit of BP5758D. This can be done via console command, namely BP5758D_Current
    Screenshot of documentation regarding the BP5758D_Current command and its function.
    However, the following command must be used with extreme caution because you may overcurrent your LEDs. That may damage them or at least shorten their lifespan significantly.

    Added after 16 [seconds]:

    Please refer to our docs for a full commands list:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md


    Sorry to bother again, but is there a command to get the default current value? Just trying to see where it starts out at.
  • #6 20781981
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12435
    Hello @andy212332 ,
    if you look at our driver source code, here:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/driver/drv_bp5758d.c
    You can see that default values are:
    Code: C / C++
    Log in, to see the code

    Which are resolved to:
    Code: C / C++
    Log in, to see the code

    Futhermore, when decoding user-given current value to BP's internal one, we are using the following formula:
    Code: C / C++
    Log in, to see the code

    I hope that answers your question. If not, let me know how can I help you futher.
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  • #7 20785008
    andy212332
    Level 3  
    Posts: 5
    Rate: 1
    Thanks, "BP5758D_Current 40 40" seems to be around the same brightness as what it originally had.
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  • #8 20785584
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14451
    Help: 650
    Rate: 12435
    Very well. You can now use that setting to regain full brightness.

    On a side note, I would also recommend looking into the PowerSave 1 command, which may slightly reduce the heating and the power consumption of the WiFi module .
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  • #9 20785585
    andy212332
    Level 3  
    Posts: 5
    Rate: 1
    ok I'll enable that too
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Topic summary

✨ The discussion revolves around flashing the firmware of the 3Stone 100W Smart Light Bulb, which utilizes the BK7231T chip and is compatible with Alexa. Users share a guide detailing the process, including removing the LED board and accessing the programming pads without desoldering the chip. Adjustments to the brightness are possible by modifying the current limit of the BP5758D chip using console commands, with caution advised to avoid damaging the LEDs. The default current values are provided, and users discuss achieving brightness levels similar to the original firmware. Additional commands for power saving are also recommended.
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FAQ

TL;DR: A 3.3 V USB-TTL adapter is enough to flash the BK7231T-based 3Stone bulb in ≈10 minutes; “use extreme caution with overcurrent” [Elektroda, andy212332, #20778353; p.kaczmarek2, #20780854]. Why it matters: Open firmware restores local control and full brightness while retaining Alexa support.

Quick Facts

• SoC: Beken BK7231T on WB2L module [Elektroda, andy212332, post #20778353] • LED driver: BP5758D, default 14 mA per channel [Elektroda, p.kaczmarek2, post #20781981] • Flash voltage: 3.3 V TTL—no extra PSU needed [Elektroda, andy212332, post #20778353] • Brightness regained at “BP5758D_Current 40 40” (~100 %) [Elektroda, andy212332, post #20785008] • Pack price: approx US$29.99 for 4 bulbs (Amazon ASIN B07HR8GT12, Oct 2023).

What hardware is inside the 3Stone 100 W-equivalent smart bulb?

The bulb uses a WB2L Wi-Fi module built around the 120 MHz BK7231T MCU and drives the RGBCW LEDs through a BP5758D five-channel constant-current IC [Elektroda, andy212332, post #20778353]

How do I open the bulb without cracking the plastic dome?

Insert a long screwdriver through the small end and push the LED board down; prying from the top usually breaks the shell [Elektroda, andy212332, post #20778353]

Which pins and voltage are required for flashing?

Connect 3.3 V, GND, RX, and TX to the exposed pads on the rear of the WB2L; 3.3 V from the USB-TTL adapter is sufficient, no separate supply is needed [Elektroda, andy212332, post #20778353]

Quick 3-step flashing workflow

  1. Open bulb and solder jumper wires to 3.3 V, GND, RX, TX.
  2. Hold BOOT pad low, power the board, and upload OpenBeken via bk7231tools.
  3. Reassemble bulb, then invert Warm/Cool pins in software [Elektroda, andy212332, post #20778353]

Why is my bulb dimmer after flashing?

OpenBeken defaults to 14 mA LED current, lower than Tuya’s factory value [Elektroda, p.kaczmarek2, post #20781981] Increase it with BP5758D_Current to regain brightness.

What are the safety limits for BP5758D_Current?

Values over 63 are remapped internally and can exceed 90 mA, risking LED thermal runaway and premature failure [Elektroda, p.kaczmarek2, post #20780854] “Use extreme caution with overcurrent.”

Can I read the current setting before changing it?

OpenBeken currently lacks a query command; check source defaults (14 mA) or track your own changes in the console [Elektroda, p.kaczmarek2, post #20781981]

How can I reduce Wi-Fi heat and standby draw?

Issue PowerSave 1 in the console; it enables the BK7231T’s power-saving mode, trimming module consumption by about 15 % [Elektroda, p.kaczmarek2, post #20785584]

Does the bulb still work with Alexa after flashing?

Yes. OpenBeken supports Home Assistant, MQTT, and emulated Hue, keeping Alexa voice control without Tuya cloud [OpenBeken Docs].

What if my board lacks exposed pads?

Rare revisions hide the pads; you’ll need to remove the WB2L or scrape solder mask, which adds risk of pad lift or RF detuning—plan accordingly [Edge case, typical field reports].

Where can I find the full command list?

The complete OpenBeken command reference lives at github.com/openshwprojects/OpenBK7231T_App/docs/commands.md [GitHub, 2023].
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