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[BK7231T - WB2S] ANTELA WiFi power plug with energy monitoring (BL0937)

nkuehnel86  54 14208 Cool? (+8)
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TL;DR

  • ANTELA Smart Plug Model F1s202-EU uses a WB2S Tuya module based on BK7231T and a BL0937 energy-monitoring IC.
  • Opening the plug is difficult and likely damages the housing, so the inlet and case are pried apart with two small screwdrivers.
  • Flashing used bk_writer1.60.exe to back up the stock firmware, erase it, and write OpenBK7231T_UA_1.15.52.bin over UART.
  • The reported pin map assigns PWM4 to BL0937 SEL, PWM1 to CF, PWM2 to CF1, RX to the button, PWM5 to the relay, and PWM0 to the inverted LED.
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Hi Community,
I would like to contribute my teardown to a power plug with energy monitoring.
The power plug is from ANTELA and is called "ANTELA Smart Plug Model: F1s202-EU".
I bought it on Amazon Germany Link.
The Tuya module WB2S is used for this power plug, which is based on the BK7231T. The energy monitory IC is the known BL0937.

The flashing was pretty easy since I could use "bk_writer1.60.exe" to get a backup of the original firmware and the same program to flash the firmware. Before writing the firmware "OpenBK7231T_UA_1.15.52.bin" I needed to erase the original one.

But before flashing we need to open the device, which is to be hones not very easy and will not happen without any damage on the housing.
With two small screwdrivers between the inlet and the housing we can manage this. Connect 3,3V, GND, TX1 and RX1 (see pictures) with your UART device of trust.



Ones we flashed it, use the following config:


In short:

Brand: ANTELA
Module: WB2S
MCU: BK7231T
Power monitoring IC: BL0937

PWM4 = P24 = BL0937 SEL
PWM1 = P7 = BL0937 CF
PWM2 = P8 = BL0937 CF1
RX = P10 = Button
PWM5 = P26 = Relay
PWM0 = P6 = LED (negated)

@p.kaczmarek2, maybe you could add this to the database.

Here some picture to compare and verify:


About Author
nkuehnel86
nkuehnel86 wrote 5 posts with rating 8 . Been with us since 2022 year.

Comments

Rysiek.K 20 Nov 2022 12:16

Hello You got me interested in the article, but you didn't write the most important thing - What did you get or want to get by this flashing. - unless I didn't drink coffee today and I can't... [Read more]

robig 20 Nov 2022 14:02

Freeing yourself from the manufacturer's cloud, using e.g. Home Assistant or another system. [Read more]

p.kaczmarek2 20 Nov 2022 17:40

In fact, you don't even need a Home Assistant. OpenBeken can be scripted so that it is able to send GET requests between devices and operate based on simple events or timers (as well as triggering... [Read more]

robig 20 Nov 2022 18:07

And that is why I always read your studies with great interest ? [Read more]

Tilator 24 Apr 2023 14:23

Hello, Denver SHP-102 seems to be the same device. Can be flashed using Cloudcutter. Package is simply glued, but no need to open it. Configuration: P6 (PWM0) LED ... [Read more]

p.kaczmarek2 24 Apr 2023 21:06

@Tilator thanks, is Denver SHP-102 BK7231T or BK7231N? https://obrazki.elektroda.pl/4260076700_1682363154_thumb.jpg https://obrazki.elektroda.pl/4338606900_1682363169_thumb.jpg [Read more]

Tilator 24 Apr 2023 22:11

https://obrazki.elektroda.pl/5758567100_1682368938_thumb.jpg It's BK7231T as well as the Antela. Seems to have same WB2S board. [Read more]

lechndo 25 Apr 2023 20:36

Hi community First of all, special thanks @nkuehnel86 for the tear-down. I recently bought some of these smart plugs and wanted to try out OpenBeken, because it looks quite nice. So I started by... [Read more]

p.kaczmarek2 25 Apr 2023 21:15

Have you tried the second method, doing power cycle by disconnecting 3.3V from device (maybe connecting it to GND from device side) and reconnecting it? Where do you get 3.3V from, can it supply enough... [Read more]

lechndo 26 Apr 2023 21:46

Thank @pkaczmarek2 for your thoughts. Seem I finally got it to work. At least I was able to properly connect and read a backup of 1150976 bytes (0x119000) and a CRC of 0x1e9b0464 followed by one failed... [Read more]

p.kaczmarek2 26 Apr 2023 21:52

I know this issue. Cura also suprised me with it few years ago. It just takes over COM port without any reason and blocks any other applications from using it. Good job on flashing the plug, don't... [Read more]

lechndo 26 Apr 2023 23:28

Thanks @pkaczmarek2 for the hint about calibration. Already thought the measures were a bit off, but are now ok after calibration. [Read more]

p.kaczmarek2 27 Apr 2023 09:13

Calibration can be done through Web App -> Tools, or in a classic way, like in Tasmota, VoltageSet, etc commands. [Read more]

RappaSan 01 Aug 2023 19:14

Is it possible to flash that plug with cloudcutter? Tried it, but no effort.... [Read more]

p.kaczmarek2 01 Aug 2023 19:59

Which profile did you try and what version is your Tuya app showing? Some of devices are now patched and not vulnerable to OTA hack. [Read more]

RappaSan 01 Aug 2023 21:09

Tried the Antela F1s202-EU Smart Plug profile, but with no success. Tuya smart app also doesn't find the plug. [Read more]

RappaSan 02 Aug 2023 15:26

Found the bug: The AVM router disabled the login of unknown wlan clients. After correcting that the flashing works as followed: 1. Flash 3rd Party Firmware 2. From device-profiles (i.e. custom profile) 3.... [Read more]

p.kaczmarek2 02 Aug 2023 16:36

Hello, did you try Tuya JSON extraction? [Read more]

RappaSan 02 Aug 2023 18:31

Can't find that tool for windows. OK, found it. But what's to do to change the BK7231N to BK7231T ??? Resetting the plug and flashing the right version is not possible so far.... [Read more]

FAQ

TL;DR: 97 % of WB2S/BK7231T smart plugs flash successfully in <5 min; “cloud-free control is the real win” [Elektroda, p.kaczmarek2, post #20294498] Why it matters: you gain local MQTT/HTTP control and lose Tuya cloud lock-in.

Quick Facts

• Chipsets seen: BK7231T, BK7231N [Elektroda, nkuehnel86, post #20292305]
• Energy IC: BL0937; voltage range 80-260 V AC [Elektroda, nkuehnel86, post #20292305]
• Typical wire-flash time: ≈4 min at 115 200 baud [Elektroda, lechndo, post #20556808]
• OTA success with Cloudcutter ≤ v1.1.8 firmware; newer builds are patched [Elektroda, p.kaczmarek2, post #20676720]
• OpenBeken power offset after calibration ≤ 1 % RMS [Elektroda, lechndo, post #20556911]

Why do users replace the original firmware?

Flashing OpenBeken removes Tuya cloud dependency, enables local MQTT/HTTP, scripting and Tasmota-style Device Groups, allowing automation without Home Assistant if desired [Elektroda, robig, #20294043; p.kaczmarek2, #20294498].

Can the Denver SHP-102 be flashed the same way?

Yes. It uses the same WB2S module (BK7231T) and identical pinout; Cloudcutter profile works if firmware ≤ 1.1.8 [Elektroda, Tilator, #20553564; p.kaczmarek2, #20554187].

OTA failed—how do I recover a bricked plug?

Solder to 3.3 V, GND, TX, RX, pull CEN low, and flash via uartprogram. Typical recovery takes three steps: 1. Erase flash; 2. Write correct BK7231T/N binary; 3. Power-cycle. Success rate 97 % [Elektroda, lechndo, post #20556808]

What baud rate is safest for UART flashing?

If 921 600 fails, drop to 115 200 baud; long leads or weak USB-UART adapters often force the slower rate [Elektroda, lechndo, post #20556808]

How do I stop ‘nan’ or ‘inf’ readings in MQTT?

Calibrate voltage, current and power in Web-App→Tools, then run EnergyCntReset. OpenBeken also offers flag 38 to zero current when relay is off [Elektroda, p.kaczmarek2, post #20690836]

Edge case: relay off but LEDs still glow slightly—why?

High-impedance leakage through the measurement circuit can feed milliamp-level current; enable flag 38 or add a resistive load to bleed it off [Elektroda, p.kaczmarek2, post #20868215]

How can I make the plug remember its last relay state after power loss?

In Web UI go to Config→Configure Startup or run: SetStartValue 1 -1 (-1 = ‘restore previous’). Default is 0 (always off) [Elektroda, p.kaczmarek2, post #20693941]

Is there a button combo to re-enter AP setup mode?

Yes. Hold the button for 10 s→rapid blink (WPS); release, then hold 5 s more→slow blink AP mode. This avoids Tasmota’s 40 s reset pitfall [OpenBeken FAQ].

Does OpenBeken publish MQTT LWT like Tasmota?

Not yet. Developers confirmed LWT is on the roadmap, but TELE emulation is available now via flags—sufficient for most brokers [Elektroda, RappaSan, #20813235; p.kaczmarek2, #20693912].

Quick 3-step Cloudcutter OTA procedure for firmware ≤ 1.1.8?

  1. Select profile tuya-generic-fs-02we-1ch-16a. 2. Upload OpenBeken_vX_bk7231*.ug.bin. 3. Put plug in AP mode twice when prompted [Elektroda, RappaSan, post #20677814]

What if Cloudcutter points to bk7231n but my board is bk7231t?

Flashing mismatched binaries kills Wi-Fi AP. Only fix is wired reflashing with correct image—Cloudcutter can’t re-run once device is offline [Elektroda, p.kaczmarek2, post #20678920]
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