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

andy212332 20 Oct 2023 20:56 9 2535 Cool? (+1)

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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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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:

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,

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andy212332 wrote 5 posts with rating 1 . Been with us since 2023 year.

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p.kaczmarek2 21 Oct 2023 09:05

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... [Read more]

andy212332 22 Oct 2023 17:44

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. [Read more]

p.kaczmarek2 22 Oct 2023 17:50

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 https://obrazki.elektroda.pl/7430665800_1697989752_thumb.jpg... [Read more]

andy212332 22 Oct 2023 18:04

Thanks, I'll check it out. Added after 13 [minutes]: Sorry to bother again, but is there a command to get the default current value? Just trying to see where it starts out at. [Read more]

p.kaczmarek2 23 Oct 2023 13:34

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: static... [Read more]

andy212332 25 Oct 2023 15:39

Thanks, "BP5758D_Current 40 40" seems to be around the same brightness as what it originally had. [Read more]

p.kaczmarek2 25 Oct 2023 21:14

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... [Read more]

andy212332 25 Oct 2023 21:15

ok I'll enable that too [Read more]

divadiow 07 Nov 2024 08:10

https://github.com/OpenBekenIOT/webapp/pull/158/commits/8950a6ff2217ee6776cbecabc64aa914f99c422f [Read more]

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]

Do I need to desolder the WB2L module?

No. The programming pads are reachable on the board edge; desoldering is optional but not required for this model [Elektroda, p.kaczmarek2, post #20778694]

Quick 3-step flashing workflow

Open bulb and solder jumper wires to 3.3 V, GND, RX, TX.
Hold BOOT pad low, power the board, and upload OpenBeken via bk7231tools.
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 command restores factory-like brightness?

Run BP5758D_Current 40 40; users report brightness matching stock firmware at that setting [Elektroda, andy212332, post #20785008]

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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