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[BK7231T] Globe Electric (GB34869) PAR20 WiFi Smart bulb - Discussion Topic

baudneo 2301 12

TL;DR

  • Globe Electric GB34869 PAR20 WiFi smart bulb discussion covers a newer revision using a BK7231N chip and an SM2135E RGW+TW LED driver.
  • Tuya Local control stopped working after a short time, with the bulb needing the mobile app and Bluetooth to wake up, so serial flashing became the path forward.
  • The board exposes Gnd, 20v, V+, 3.3V, CLK, and SDA, and the bulb runs firmware 1.5.21 with Tuya protocol 3.5.
  • Flashing succeeded without desoldering the daughter board, and GPIO detector JSON enabled switching and RGB color control, but brightness is low and white temperature turns the bulb off.
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  • Hi, I am researching before I go cracking open 1 of my 6 bulbs.

    I had originally tried controlling these through HASS using Tuya Local library. The problem with these bulbs is that after a short duration of time, the bulbs go unresponsive and require using the mobile app and Bluetooth to 'wake' the bulbs up before they start accepting commands again. I can't implement a way to wake the bulbs using BLE and HASS while they are running their original firmware, so here I am.

    I've read up and watched several videos but, from the FCC internal photos, the daughter board is quite different than all the examples I have seen. I am just wondering if this type of board has already been flashed by any users here or if anyone can help me ascertain how to flash the chip.

    Here is a photo of the board:
    Close-up of a circuit board with BK7231TQN32 chip.

    and here is the FCC URL for the bulb.

    TIA!


    Added after 2 [hours] 2 [minutes]:

    Here are some more pics, this is apparently a newer revision as it uses the 7231N chip. I first tried tuya-cloudcutter but they don't have make/model or firmware version that this bulb has, the bulb has 1.5.21 firmware (tuya protocol 3.5). So, I am left with flashing via serial. The last picture is of the led board and has pinouts for the header on the PSU board.

    - Gnd
    - 20v
    - V+
    - 3.3V
    - CLK
    - SDA

    The 2nd last pic is the PSU PCB (to help ascertain what's what). I am wondering how I would connect this to my usb serial adapter?

    Thanks!

    Circuit board of a light bulb with visible electronic components.
    Close-up of a small electronic circuit board with visible traces and markings.
    Electronic board with a chip and quartz oscillator on a wooden background.


    Close-up of a circuit board with a chip and capacitor in a light bulb.

    Close-up of an LED bulb circuit board showing tracks and components.
    LED lighting module on a PCB with labeled connectors and electronic components.

    The board has it as an rgw+tw (sm2135e) and it has a 26000 crystal oscillator on the daughter board that is not present in the FCC internal pics.

    If there is anymore information I can give, plz let me know!

    Thanks!

    Added after 5 [hours] 5 [minutes]:

    So, I managed to get it flashed but now am tryign to figure out how to configure it properly. I did not need to desolder the daughter board but, it was good practice.

    I imported the JSON that the GPIO detector supplied adn I can toggle the light and change its RGB color. Its brightness is very low, the RGB colors need tuning and the white temperture slider turns the bulb off. I will comb through the docs to see if I can figure out how to get it working better.

    Happy that this project exists!

    Cool? Ranking DIY
    About Author
    baudneo
    Level 6  
    Offline 
    baudneo wrote 17 posts with rating 5, helped 1 times. Been with us since 2023 year.
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  • #2 20719800
    p.kaczmarek2
    Moderator Smart Home  
    Thank you for the presentation, can you attach 2MB firmware dump or at least Tuya config partition?

    It looks like you need to adjust the RGB/CW current, maybe also enable SM2135 alternate mode flag. Search for SM2135_Current:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md
    Helpful post? Buy me a coffee.
  • #3 20720243
    baudneo
    Level 6  
    I backedup the fw before i wrote to it but, the tuya-cloudcutter profile_builder.py script errors out when building a profile. I also have the .bin file from reading tuya config @ 0x1EE000.

    Tuya Cloudcutter profile builder error:
    Code: Bash
    Log in, to see the code


    There is a file folder with decrypted.bin and bootloader.bin even though the script failed.
    Code: Bash
    Log in, to see the code



    Firmware 2MB backup file: Globe-Elec...-RGBCT.bin (2 MB)You must be logged in to download this attachment.

    Tuya Config backup: BK7231N_Tu...F48BD8.bin (72 kB)You must be logged in to download this attachment.

    Here is the JSON from the writing process that I imported in the WebApp:
    Code: JSON
    Log in, to see the code



    I changed one of the sm2135 flags to send sepearate WW and CW and now the white temp slider works and the brightness is on par with stock tuya fw. After a second look of the bulbs beside stock tuya fw bulbs, the colors are correct. With the flags set, the bulb colors/temp/brightness are the same as stock tuya fw. Here are the flags I set: 5632.

    I will make another post of a full teardown and flashing as I have 5 more bulbs to do with the hopes of it being added to the product DB.

    Thanks for your work and effort, you have freed me from insidious tuya and their death grip on consumer IoT products.
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  • #4 20720472
    baudneo
    Level 6  

    Well, this really really sucks. I flashed my 2nd/6 bulb and it all went well. Upon reassembly, it does not work. I used the "change OBK settings for flash write" and added my SSID/PW, MQTT broker info and then flags 9,10,12. The bulb never connects to the SSID and does not broadcast an AP. I went to go solder wires onto it again but, I lost RX1 pad so, I am unsure how I can flash it again......

    I probed the connector and there is 160VDC on V+, 3.3 on 3.3V. and Ground obviously is connected. I am not sure how I can test if the chip is getting power or not. I'm guessing this chip is toast. I am moving onto bulb 3/6. Soldering the TX and RX wires is a nightmare on this little board!
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    #5 20720482
    p.kaczmarek2
    Moderator Smart Home  
    If you have made adjustments to the config, please also post the final template from the Web App, or at least make sure to include it in the final teardown. That's where all the settings and flags are.

    If your bulb does not connect to the WiFi, try doing 5 quick power off/on cycles to enable safe mode (AP mode) for OpenBeken and diagnose the problem.

    See our help:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/README.md
    And F.A.Q.:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/faq.md
    Helpful post? Buy me a coffee.
  • #6 20721160
    baudneo
    Level 6  

    p.kaczmarek2 wrote:
    If you have made adjustments to the config, please also post the final template from the Web App, or at least make sure to include it in the final teardown. That's where all the settings and flags are.

    If your bulb does not connect to the WiFi, try doing 5 quick power off/on cycles to enable safe mode (AP mode) for OpenBeken and diagnose the problem.

    See our help:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/README.md
    And F.A.Q.:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/faq.md


    The 5 power off/on trick did it! I had a typo in SSID. I will create a new post with the teardown and pertinent settings.

    Thank you! I will be sending some support your way!
  • #7 20721187
    p.kaczmarek2
    Moderator Smart Home  
    Thank you, all support funds go towards the development of new features, tutorials and devices. Just look at our list, we're heading towards 400 entries soon:
    https://openbekeniot.github.io/webapp/devicesList.html
    Many of them are my teardowns. Thanks to this, every smart device in my house is a different model :D

    Let me know if there is anything more I can do for you, I can implement features per request.
    Helpful post? Buy me a coffee.
  • #9 20721296
    p.kaczmarek2
    Moderator Smart Home  
    I am usually adding device to teardowns list myself, but first I need JSON.

    The devices list database is here:
    https://github.com/OpenBekenIOT/webapp/blob/gh-pages/devices.json
    If you want to do the honors, open a pull request adding your JSON to the list.

    If not, I will add your JSON yourself, just make sure to post it.

    The JSON should consist device GPIO, generic tags and related keywords, forum image link and topic link.

    Please note that we have our own image hosting here at Elektroda, so there is no risk of your device expiring like the ImageShack images did, etc, etc.
    Helpful post? Buy me a coffee.
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  • #10 20721429
    baudneo
    Level 6  

    I have one last question, I think it is specific to MQTT light entity possibly or maybe I need to add an MQTT flag.

    In HASS, I have a helper group that contains 3 OBK lights. If I change the group to a color and then I turn the group off. When I turn the group back on, the color is set to warm white instead of whatever color they were before they were toggled off. Do you know of a way to have the bulbs in HASS remember their color or is that a HASS issue?

    Thanks!
  • #11 20722365
    p.kaczmarek2
    Moderator Smart Home  
    What do you mean exactly by "turn off", do you mean disconnect power from the bulbs, so WiFi is also down, or do you mean just disable LEDs via OBK?

    I don't remember this issue. It should keep the color. You can try that by manually sending command:
    Code: text Expand Select all Copy to clipboard
    
cmnd/OBK_DEV_NAME/led_enableAll

    with payload 1 or 0.

    Or do you want to make OBK remember LED state between power sessions? There is a flag for that.
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  • #12 20723511
    baudneo
    Level 6  
    Hi, by turn off I ment I toggled the bulb off using home assistant entity switch. I did set the power off remember state flag.
  • #13 20723523
    p.kaczmarek2
    Moderator Smart Home  
    That's strange. Does manually sending just a simple led_enableAll 1 (or with 0) via MQTT also changes the colors?

    I am asking because HA might be sending some more data along with that.
    Helpful post? Buy me a coffee.
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Topic summary

✨ The discussion revolves around the Globe Electric (GB34869) PAR20 WiFi Smart bulb, specifically issues related to its firmware and integration with Home Assistant (HASS) using the Tuya Local library. Users report that the bulbs become unresponsive after a short period, requiring a mobile app and Bluetooth to reactivate. One user attempts to flash the bulb's firmware but encounters errors with the Tuya Cloudcutter profile builder and issues with WiFi connectivity post-flashing. Solutions discussed include adjusting RGB/CW current settings, enabling specific flags, and using a power cycling method to enter safe mode. The conversation also touches on MQTT configurations for maintaining color settings in HASS after toggling the bulbs off. Ultimately, users share troubleshooting steps and resources for flashing and configuring the bulbs.
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FAQ

TL;DR: OpenBeken already supports 380+ devices [Elektroda, p.kaczmarek2, post #20721187]; "The 5 power off/on trick did it!" [Elektroda, baudneo, post #20721160] Flash the Globe Electric GB34869 PAR20 (BK7231T/N) via serial, set SM2135 flags, and recover with a 5-cycle safe mode.

Why it matters: You swap Tuya’s unstable cloud firmware for fully-local, reliable control.

Quick Facts

• MCU: Bouffalo BK7231T/BK7231N, 32-bit, 2 MB flash [Elektroda, baudneo, post #20719259] • LED driver: SM2135E, supports RGB + CW/WW channels [Elektroda, baudneo, post #20719259] • Supply rails measured: 160 V DC (V+), 3.3 V (logic) [Elektroda, baudneo, post #20720472] • Safe-mode entry: 5 rapid power cycles (<8 s total) [Elektroda, p.kaczmarek2, post #20720482] • Typical flash time: <90 s at 115 200 bps (OpenBK wiki).

What hardware is inside the Globe Electric GB34869 PAR20 Wi-Fi bulb?

The bulb uses a BK7231T or newer BK7231N Wi-Fi MCU module on a small daughter-board, an SM2135E five-channel LED driver, a 26 MHz crystal, and a high-voltage SMPS that provides 3.3 V logic and about 20 V LED power [Elektroda, baudneo, post #20719259]

Can I flash it over-the-air with Tuya-cloudcutter?

No. Cloudcutter cannot decrypt the 1.5.21 firmware; the profile builder throws a CRC-16 error [Elektroda, baudneo, post #20720243] Use wired UART flashing instead.

How do I wire the serial adapter?

Connect USB-TTL (3.3 V) pins: TX->RX1, RX->TX1, GND->GND, and power the board through the bulb’s own supply. Leave V+ and 20 V unconnected. Baud rate 115 200, 8-N-1 [Elektroda, baudneo, post #20719259]

Which OpenBeken template works?

Import the auto-detected GPIO JSON, then set SM2135 flags 5632 to enable separate CW/WW and proper currents. This restores correct brightness and color temperature [Elektroda, baudneo, post #20720243]

Brightness is low and white slider turns the bulb off—how can I fix it?

Increase SM2135_Current and enable the SM2135 alternate-mode flag. After setting flags 5632, RGB and CW/WW output match stock levels [Elektroda, p.kaczmarek2, #20719800; baudneo, #20720243].

I lost the RX1 pad—can I still recover the bulb?

Unfortunately, if RX1 is torn off you cannot enter bootloader via UART. Replace the module or use SWD if exposed; otherwise the unit is bricked (edge-case noted by [Elektroda, baudneo, post #20720472]).

Home Assistant turns the group back on as warm-white—how do I keep the last color?

HA may send an empty payload when toggling. Ensure each light has the “retain” flag and set OBK Flag 6 (remember PWM state). Alternatively, send led_enableAll 0/1 via MQTT instead of power toggle, which preserves HSV values [Elektroda, p.kaczmarek2, post #20722365]

How can I dump the original Tuya firmware for backup?

Read the full 0x0–0x1FFFFF flash range (2 MB) with obd flash_dump. Save config partition at 0x1EE000 separately. The forum dump proves this fits in a single 2 MB file [Elektroda, baudneo, post #20720243]

How do I add this bulb to the OpenBeken device list?

Fork github.com/OpenBekenIOT/webapp, append your JSON (GPIO map, tags, forum image link, topic URL) to devices.json, and open a pull request. If you skip this, moderators will add it once JSON appears in the thread [Elektroda, p.kaczmarek2, post #20721296]

Quick 3-step flashing guide

  1. Solder temporary wires to 3.3 V, GND, TX1, RX1.
  2. Run obkflash write OpenBK7231T_Generic.bin at 115 200 bps.
  3. Power-cycle five times, connect to OBK-AP, upload template, set SM2135 flags.
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