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

baudneo 03 Sep 2023 06:50 12 2301 Cool? (0)

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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:

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!

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!

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baudneo wrote 17 posts with rating 5 , helped 1 times. Been with us since 2023 year.

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p.kaczmarek2 03 Sep 2023 13:49

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.... [Read more]

baudneo 03 Sep 2023 19:26

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... [Read more]

baudneo 03 Sep 2023 22:59

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... [Read more]

p.kaczmarek2 03 Sep 2023 23:08

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... [Read more]

baudneo 04 Sep 2023 16:51

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! [Read more]

p.kaczmarek2 04 Sep 2023 17:23

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... [Read more]

baudneo 04 Sep 2023 18:26

I added a teardown, not sure how to get the device added to the device list. There are 3 versions of this bulb, so v1/v2 may be different for the flashing part. https://www.elektroda.com/rtvforum/vie... [Read more]

p.kaczmarek2 04 Sep 2023 19:01

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... [Read more]

baudneo 04 Sep 2023 20:48

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... [Read more]

p.kaczmarek2 05 Sep 2023 17:45

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.... [Read more]

baudneo 06 Sep 2023 17:36

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. [Read more]

p.kaczmarek2 06 Sep 2023 17:42

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. [Read more]

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].

What SM2135 flags do I actually need?

Use flags 9, 10, 12 for I²C, plus 5632 for alternate CW/WW mapping. Total flag value: 5632 [Elektroda, baudneo, post #20720472]

The bulb won’t join Wi-Fi after flashing—what now?

Toggle mains power five times quickly. OpenBeken enters safe-mode AP, letting you fix SSID or MQTT typos [Elektroda, p.kaczmarek2, post #20720482]

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

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

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