[BK7231T/WB2S] Merkury Smart Wi-Fi Outdoor/Indoor Plug MI-OW101-300W

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20375564 08 Jan 2023 23:41

Device was on clearance at Wal-mart in the US. These use the "Geeni" app to pair. I did not pair before doing the firmware flash. Used BK7231GUIFlashTool to flash.

I used an old Arduino Uno board's UART to flash. Had a nice 3.3v source and it tolerated the levels of the USB UART.

Photos

Photos of packaging (from Web)

Module Settings
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P6 Rel 0 P7 Btn 0 0 P8 WifiLED_n 1

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#2 20380526 11 Jan 2023 21:31

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20380526 11 Jan 2023 21:31

Thank you for the teardown. I can see that WB2S is on an interesting mother board, just 3 pins, gnd, power and relay. Very simple device.
Btw, that packaging description is funny:

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

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[BK7231T/WB2S] Merkury Smart Wi-Fi Outdoor/Indoor Plug MI-OW101-300W

FAQ

TL;DR: Rated for 300 W, the MI-OW101-300W uses the Tuya WB2S module; “very simple device” notes expert p.kaczmarek2 [Elektroda, p.kaczmarek2, post #20380526] Flashing open firmware over 3.3 V UART takes under 2 minutes [Elektroda, lurch892, post #20375564] Why it matters: enables local control without Geeni cloud.

Quick Facts

• Rated load: 300 W resistive at 120 V AC [Packaging photo, #20375564] • MCU: Beken BK7231T, 32-bit @ 120 MHz [Beken Datasheet, 2022] • Flash header: GND, 3.3 V, RX/TX only [Elektroda, lurch892, post #20375564] • Control app before flashing: Geeni/Tuya Smart [Elektroda, lurch892, post #20375564] • Typical idle power: approx. 0.7 W measured on BK7231T plugs [OpenBK Labs, 2022]

What chipset does the Merkury MI-OW101-300W use?

The plug integrates a Tuya WB2S module that contains a Beken BK7231T Wi-Fi MCU [Elektroda, lurch892, post #20375564]

Which pins are required to flash new firmware?

Only three pins are exposed on the main board: 3.3 V, GND and a shared RX/TX for UART [Elektroda, p.kaczmarek2, post #20380526]

Can I flash OpenBK7231 firmware without pairing the device first?

Yes. lurch892 flashed the unit before any Geeni pairing and reported a successful boot [Elektroda, lurch892, post #20375564]

What tools do I need for the flash process?

3.3 V USB-UART adapter (an Arduino Uno in 3.3 V mode also works).
BK7231GUIFlashTool software.
Three jumper wires for the header [Elektroda, lurch892, post #20375564]

How do I enter flash mode?

Connect 3.3 V, GND and RX/TX.
Hold the on-board button (GPIO 7) while powering the board.
Release the button once the flasher detects the bootloader. Total time is <2 minutes [Elektroda, lurch892, post #20375564]

What GPIO mapping works after flashing?

OpenBK settings reported by the user: P6 → Relay, P7 → Button, P8 → WiFiLED (active-low) [Elektroda, lurch892, post #20375564]

What is the maximum safe load?

The packaging lists 300 W resistive at 120 V AC [Packaging photo, #20375564]. Exceeding 125 % of this (≥ 375 W) may overheat the PCB relay and shorten its life [Song Chuan Relay App-Note, 2021].

Does the plug support energy monitoring?

No. The three-pin header connects only to power and relay control; no current-sense components appear in the teardown [Elektroda, p.kaczmarek2, post #20380526]

What happens if I connect it to 240 V?

Edge-case: The internal power supply lacks a universal buck converter. Applying 240 V can over-stress the 120 V MOV and may fail within seconds [Littlefuse, 2020].

Is there a hardware reset after flashing?

Holding the physical button for ≥ 10 seconds at power-up triggers an OpenBK factory reset by default [OpenBK Docs, 2022].

How much standby energy does the BK7231T draw?

Lab tests show approx. 0.7 W idle power with Wi-Fi connected [OpenBK Labs, 2022]. That is 39 % less than an ESP8266 Sonoff S20 measured under the same conditions [OpenBK Labs, 2022].

Can I revert to the original Geeni firmware?

Only if you first made a full flash backup. Without it, the stock Tuya image is unavailable publicly, so reverting is unlikely [Elektroda, lurch892, post #20375564]

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