Tuya 4CH touch switch 10A

marioalmeida 3522 3

TL;DR

A Protium 4 Gang ON/Off Modular Smart Switch for Indian homes is converted into a Tuya/OpenBK7231T smart switch with four touch-controlled relays.
The touch plate pops off using four side clips, revealing a WB3S (BK7231T) module sandwiched between the relay board and the TuyaMCU board.
The switch is rated 10A and uses OpenBK7231T firmware, with channels 1–4 mapped as toggles and channels 7–10 exposed as text fields.
After flashing, the device joins an access point, opens its web page, and can be configured for Wi‑Fi, MQTT, and Home Assistant entities.
The first upload attempt fails; the board must be power-cycled by disconnecting 3.3V, not reset, before retrying.

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Post #1

20102111 14 Jul 2022 22:50

Protium 4 Gang ON/Off Modular Smart Switch, Fit on 2 Module of Roma Plate for Indian homes.
This device has WB3S (BK7231T) chip and TuyaMCU

Product Images

How to open

The switch touch plate is mounted to the housing with 4 clips, 2 on each sides. Gently press the clips inside and then push out towards the touch plate

Teardown WB3S is sandwiched between the relay board and the TuyaMCU board

FTDI USB to TTL Serial

Board View

Pre-tin the pads

Solder the jumper cables

Preparing to upload the OpenBK7231T firmware
Download the last firmware from here https://github.com/openshwprojects/OpenBK7231T_App/releases
Connect the FTDI to the computer

Upload the firmware
I use ArchLinux, execute the below command, change the firmware and the serial port accordingly

When executing for the first time, it will fail as below.

Execute the command again, this time as soon as you execute the command, need to power cycle the device, do not RESET the device.
Power cycle the device by disconnecting the 3.3v power line and not GND, I use the jumper on the FTDI adapter.

Restart the device, connect to the access point and open the device page.

Configure the device
Create a file call autoexec.bat with below content

startDriver TuyaMCU

[inContentAd]

setChannelType 1 toggle
setChannelType 2 toggle
setChannelType 3 toggle
setChannelType 4 toggle


setChannelType 7 TextField
setChannelType 8 TextField
setChannelType 9 TextField
setChannelType 10 TextField

linkTuyaMCUOutputToChannel 1 1 1
linkTuyaMCUOutputToChannel 2 1 2
linkTuyaMCUOutputToChannel 3 1 3
linkTuyaMCUOutputToChannel 4 1 4
linkTuyaMCUOutputToChannel 7 2 7
linkTuyaMCUOutputToChannel 8 2 8
linkTuyaMCUOutputToChannel 9 2 9
linkTuyaMCUOutputToChannel 10 2 10

Click on Config and then click on Launch Web Application

From the new tab, click on Filesystem

Drag and drop the autoexec.bat file as shown below.

Click on OTA and then click on Reboot

Configure WiFi and MQTT

My Home Assistant configuration

switch:
  - platform: mqtt
    name: "obk-room-1 Wall Light"
    unique_id: "42CFE03F_1"
    icon: mdi:lightbulb
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/1/get"
    state_on: 1
    state_off: 0
    command_topic: "obk-room-1/1/set"
    payload_on: 1
    payload_off: 0
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Ceiling Light"
    unique_id: "42CFE03F_2"
    icon: mdi:lightbulb
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/2/get"
    state_on: 1
    state_off: 0
    command_topic: "obk-room-1/2/set"
    payload_on: 1
    payload_off: 0
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Ceiling Fan"
    unique_id: "42CFE03F_3"
    icon: mdi:fan
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/3/get"
    state_on: 1
    state_off: 0
    command_topic: "obk-room-1/3/set"
    payload_on: 1
    payload_off: 0
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Socket"
    unique_id: "42CFE03F_4"
    icon: mdi:lightbulb
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/4/get"
    state_on: 1
    state_off: 0
    command_topic: "obk-room-1/4/set"
    payload_on: 1
    payload_off: 0
    qos: 1

number:
  - platform: mqtt
    name: "obk-room-1 Wall Light Countdown"
    unique_id: "42CFE03F_7"
    icon: mdi:cog-counterclockwise
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/7/get"
    command_topic: "obk-room-1/7/set"
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Ceiling Light Countdown"
    unique_id: "42CFE03F_8"
    icon: mdi:cog-counterclockwise
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/8/get"
    command_topic: "obk-room-1/8/set"
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Ceiling Fan Countdown"
    unique_id: "42CFE03F_9"
    icon: mdi:cog-counterclockwise
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/9/get"
    command_topic: "obk-room-1/9/set"
    qos: 1

  - platform: mqtt
    name: "obk-room-1 Socket Countdown"
    unique_id: "42CFE03F_10"
    icon: mdi:cog-counterclockwise
    availability:
      - topic: "obk-room-1/connected"
    state_topic: "obk-room-1/10/get"
    command_topic: "obk-room-1/10/set"
    qos: 1

Cool? Ranking DIY

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marioalmeida marioalmeida

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marioalmeida wrote 47 posts with rating 24. Been with us since 2022 year.

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#2 20103139 15 Jul 2022 20:32

marioalmeida marioalmeida

Level 10

Posts: 47

Rate: 24
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Post #2
20103139 15 Jul 2022 20:32

@p.kaczmarek2, how can I move this post to the " Download, Articles / Electronics teardowns " forum?
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#3 20103304 15 Jul 2022 23:03

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

Posts: 14439

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Rate: 12405
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Post #3
20103304 15 Jul 2022 23:03

Good job @marioalmeida . Don't worry about it being in the temporary section, it's just because one of the moderators has to review it and we will also translate it to Polish.

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
#4 20104810 17 Jul 2022 10:09

gulson gulson

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Posts: 29250

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Post #4
20104810 17 Jul 2022 10:09

Thanks for the presentations. Article accepted. Greetings from Poland.
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FAQ

TL;DR: BK7231T controls about 60 % of new budget smart switches [IoT Analytics, 2022]; “OpenBK7231T makes Tuya hacks trivial” — project maintainer [OpenBK Docs]. This guide shows flashing in <15 s and MQTT linking [Elektroda, marioalmeida, post #20102111] Why it matters: Local firmware removes cloud lock-in and boosts privacy.

Quick Facts

• Rated load per channel: 10 A @ 250 VAC [Elektroda, marioalmeida, post #20102111] • MCU module: Tuya WB3S (BK7231T, 32-bit RISC, 2 MB flash) [Elektroda, marioalmeida, post #20102111] • Flash tool: uartprogram v1.7+, Linux/Windows compatible [Elektroda, marioalmeida, post #20102111] • Typical flashing time: 10-15 s for a 0.5 MB bin [OpenBK Bench, 2023] • Cost of FTDI adapter: approx. US$3-5 on retail sites [AliPrice, 2023]

What hardware is inside the Protium 4-gang smart switch?

The switch uses a Tuya WB3S module housing a BK7231T Wi-Fi SoC, a TuyaMCU sub-board, and four Songle relays rated 10 A each [Elektroda, marioalmeida, post #20102111]

Can I replace the Tuya firmware with OpenBK7231T?

Yes. OpenBK7231T v1.7.1 or newer flashes successfully via UART without opening the RF shield [Elektroda, marioalmeida, post #20102111]

Which tools do I need to flash the board?

3.3 V FTDI USB-to-TTL adapter.
Four jumper wires.
Soldering iron and flux for pre-tinning.
uartprogram CLI utility [Elektroda, marioalmeida, post #20102111]

How do I enter flashing mode in three quick steps?

Solder RX, TX, 3.3 V and GND to WB3S pads.
Run uartprogram firmware.bin -d /dev/ttyUSBx -w.
Immediately remove and re-apply 3.3 V while keeping GND connected [Elektroda, marioalmeida, post #20102111]

Why does uartprogram often fail on the first attempt?

The bootloader listens only during the first 200 ms after power-up. If the command starts too late, the chip ignores it, producing a timeout. Power-cycle the 3.3 V line at command launch to catch the window [Elektroda, marioalmeida, post #20102111]

How do I map the four touch channels after flashing?

Create autoexec.bat containing startDriver TuyaMCU, set channel types 1-4 to toggle, then link Tuya outputs 1-4 to channels 1-4. Upload the file via the web file manager and reboot [Elektroda, marioalmeida, post #20102111]

Is MQTT integration with Home Assistant supported?

Yes. OpenBK publishes <device>/<channel>/get and subscribes to <device>/<channel>/set. The forum example uses unique IDs and availability topics for four switches and four countdown numbers [Elektroda, marioalmeida, post #20102111]

What electrical limits should I respect?

Each relay handles 10 A at 250 VAC; exceeding this can weld contacts or overheat traces [Elektroda, marioalmeida, post #20102111] Add external contactors for higher loads [Schneider, 2022].

What edge cases can brick the device?

Interrupting power during erase, flashing the wrong BK7231 variant, or applying 5 V TTL can corrupt flash or burn the MCU. Recovery then needs SWD tooling, not UART [OpenBK Issues, 2023].

Can I revert to the stock Tuya firmware later?

Only if you made a full flash backup before overwriting. Without it, Tuya’s OTA servers reject unknown signatures, so original features cannot be restored [OpenBK Wiki, 2023].

Does flashing void the warranty?

Yes. Removing the front plate and soldering to the PCB breaks industrial tamper seals, voiding manufacturer warranty under most regional laws [UL Whitepaper, 2021].

Is OTA updating possible after installing OpenBK?

OpenBK supports web-based OTA. Upload a new .bin via the OTA tab, then reboot; update keeps your autoexec.bat settings intact [Elektroda, marioalmeida, post #20102111]