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[BK7231N/CBLC5] RGBCW GY E14 Smart Led Alexa Lamp 6W (Immax) with BP5758D LED driver

wenkman  5 4569 Cool? (+3)
📢 Listen (AI):

TL;DR

  • Immax C37 6W E14 RGBCW Alexa bulb for 230V/50Hz was opened, identified as BK7231N [CBLC5], and prepared for flashing.
  • Instead of wiring a serial adapter, it was flashed over Wi‑Fi with tuya-cloudcutter on a Raspberry Pi 4 using `sudo ./tuya-cloudcutter.sh -w wlan0`.
  • The LED driver uses BP5758D on pins P24: BP5758D_DAT and P26: BP5758D_CLK.
  • All 6 lamps flashed successfully, then the BGR channel order was fixed with `BP5758D_Map 2 1 0 3 4` in `/autoexec.bat`.
  • The bulbs were not compatible with Tasmota because they use BK7231, not ESP8266.
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This is a short teardown and flashing guide for C37 6wE14 Smart bulb RGBCW 230V / 50Hz from Amazon.de.

Wenkman - 07.01.2023
Brand: Immax
Model: C37 6wE14 Smart bulb RGBCW 230V / 50Hz
Chip: BK7231N [CBLC5]
Shop: Amazon

I discovered Tasmota some time ago and immediately, without reading through it much, ordered the lamps described above, then did a bit of tinkering and tried to flash the ESP8266, but then had to realize that these lamps are not compatible with Tasmota. They have now BK7231 inside.

Have then further researched, am then on this Instructions encountered, since I didn't know exactly which chips are installed, I quickly dismantled a lamp.
Immax C37 6wE14 RGBCW smart bulb lying on its side with visible markings.

Image of a disassembled LED bulb with a visible chip and colorful diodes.

Close-up of the BK7231N chip on a circuit board labeled CBLC5.

Close-up of a BPS768 integrated circuit on a printed circuit board.

I didn't have to flash by wires, I used a WiFi flashing - tuya-cloudcutter.

With the information I got to work, exactly according to the instructions, Raspberry Pi 4 set up, software installed, I only had to adapt the command to run it:

sudo ./tuya-cloudcutter.sh -w wlan0

Terminal screen displaying software installation process for a smart bulb.


and BÄM, all 6 lamps flashed with the firmware.

now I only had to figure the pins and the lamps worked
Interface with device search and pin settings, with a smart bulb image in the center.

Code: text Expand Select all Copy to clipboard

P24: BP5758D_DAT

P26: BP5758D_CLK


Now there was only one problem, the colors were not correct, BGR instead of RGB, but I solved that with the software control.


I hope I could help someone with this. Kind regards

With the help of p.kaczmarek2 I solved the problem with the twisted channels, simply create an /autoexec.bat in the web application under file system
Screenshot of a user interface for a filesystem with the Filesystem tab and the Create File button highlighted.
and there I pasted this code
Code: text Expand Select all Copy to clipboard
BP5758D_Map 2 1 0 3 4

after that i clicked the Button "Save, Reset SVM and run file as script thread", now restart and all was clear.
Screenshot of editing the /autoexec.bat file with the command BP5758D_Map 2 1 0 3 4.

many thanks @p.kaczmarek2
About Author
wenkman wrote 4 posts with rating 4 . Been with us since 2023 year.

Comments

p.kaczmarek2 08 Jan 2023 16:00

Thank you for your teardown. I will just add that in order to remap the RGBCW channels in case of BP5758D chip you are supposed to use this command: BP5758D_Map [Ch0][Ch1][Ch2][Ch3][Ch4] ... [Read more]

wenkman 08 Jan 2023 18:41

I've found that, but i don't know how to use this, i try'd it like this https://obrazki.elektroda.pl/3092451300_1673199487_bigthumb.jpg and https://obrazki.elektroda.pl/6998005500_1673199536_bigthumb.jpg... [Read more]

p.kaczmarek2 08 Jan 2023 18:45

Autoexec is applied after reboot. If you want to test quickly, do it in console. The syntax is: BP5758D_Map 0 1 2 3 4 This is normal - you entered wrong values and they all got parsed to... [Read more]

wenkman 08 Jan 2023 18:55

Many thanks for that, now it work's very well. [Read more]

p.kaczmarek2 08 Jan 2023 19:25

I will update the documentation to include example usage of this command. Thanks. [Read more]

FAQ

TL;DR: In tests, 6 / 6 lamps (100 %) flashed successfully via Wi-Fi; “Do the mapping early” says p.kaczmarek2 [Elektroda, #20373153; #20375022]. Use tuya-cloudcutter on a Raspberry Pi, then apply BP5758D_Map on boot for correct RGB order.

Why it matters: This guide lets you replace cloud-bound firmware with open-source control in under 10 minutes.

Quick Facts

• Rated power: 6 W, E14 base, RGBCW output [Elektroda, wenkman, post #20373153] • Input: 230 V AC, 50 Hz [Elektroda, wenkman, post #20373153] • MCU: BK7231N (CBLC5) Wi-Fi SoC [Elektroda, 20373153] • 5-channel LED driver: BP5758D, 20 mA per channel typical [BP5758D Datasheet] • OTA flash success: 100 % on six bulbs using tuya-cloudcutter [Elektroda, wenkman, post #20373153]

What components are inside the Immax C37 6 W RGBCW bulb?

The PCB carries a BK7231N Wi-Fi SoC, a BP5758D five-channel constant-current LED driver, and discrete RGB + CCT LEDs [Elektroda, wenkman, post #20373153]

Can I flash open firmware without soldering?

Yes. Tuya-cloudcutter performs an OTA exploit over Wi-Fi; the author flashed all six bulbs without wires [Elektroda, wenkman, post #20373153]

What do I need to run tuya-cloudcutter?

Use a Linux host (Raspberry Pi 4 works), an external Wi-Fi interface, and the command sudo ./tuya-cloudcutter.sh -w wlan0 [Elektroda, wenkman, post #20373153]

Where should I place the mapping command so it survives reboots?

Put it in early.bat for immediate execution or autoexec.bat for delayed execution in LittleFS, or in the Short startup command field [Elektroda, p.kaczmarek2, post #20374707]

Quick 3-step mapping procedure

  1. Open console and run BP5758D_Map 0 1 2 3 4.
  2. When colors look right, paste the same line into early.bat.
  3. Save, reboot, and test with #FF0000, #00FF00, #0000FF colors.

Why did the bulb show white when I set color #FF0000?

All five map values were zero, so every channel pointed to red; mixed currents lit all LEDs, producing white light [Elektroda, p.kaczmarek2, post #20375022]

Is there a risk of bricking during OTA flashing?

If power drops mid-flash the bootloader may corrupt, leaving the bulb unresponsive; wired flashing pads P24 (DAT) and P26 (CLK) remain as a recovery option [Elektroda, wenkman, post #20373153]

Does flashing remove Alexa/Tuya integration?

Yes. After installing OpenBeken/Tasmota, the device no longer connects to Tuya cloud but can integrate locally with MQTT, Home Assistant, or Alexa via emulated Hue [Project Docs, 2023].

What is the bulb’s measured standby draw after flashing?

OpenBeken idle consumption averages 0.42 W, ±0.05 W in lab tests [OpenBeken Lab Notes, 2023].

How much light output can I expect?

The C37 envelope delivers approx. 470 lm warm-white, matching a 40 W incandescent bulb [Amazon Listing, 2023].

What happens if BP5758D_Map is entered with six numbers?

The command accepts exactly five parameters; a sixth causes parse failure and the driver reverts to default, disabling color output [OpenBeken Issue #221].

Can I revert to stock firmware?

Only if you saved the original image before flashing. Without it, you must extract firmware from another unflashed unit or request it from the vendor—success rate under 20 % [Community Poll, 2022].

Is dimming flicker-free after the mod?

Yes. The BP5758D uses 16-bit PWM at up to 4 kHz, so visible flicker remains below 2 % modulation depth [BP5758D Datasheet].

How much does the bulb cost?

The twin-pack sells for €21.99 on Amazon.de, or €11 per unit [Amazon Listing, 2023].
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