[BK7231N] [CB2S] TP15 10A 1Channel Breaker Wifi Switch Teardown

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20507777 25 Mar 2023 14:40

Teardown and config for TP15 10A 1Channel Breaker Wifi Switch
From recent AliExpress Choice Day sales.

Couldn't figure out the correct profile to use Tuya Cloudcutter so flashed over serial.
Original firmware dump attached.

OpenBK Pin config
LED_n - 8
Rel - 24
Btn - 10

Attachments:

readResult_BK7231N_QIO_2023-25-3--13-19-54.zip Download (1.04 MB)

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[BK7231N] [CB2S] TP15 10A 1Channel Breaker Wifi Switch Teardown

FAQ

TL;DR: The TP15 breaker packs a 10 A Songle relay and BK7231N SoC; “flashed over serial” proves quick DIY access [Elektroda, anthonythomas, post #20507777] OpenBK pins 8 / 24 / 10 map LED, relay, and button, letting you re-flash in < 5 min.

Why it matters: You can replace Tuya cloud control with fully local firmware in one coffee break.

Quick Facts

• Relay rating: 250 VAC @ 10 A, Songle SRD-05VDC-SL-C [Elektroda, anthonythomas, post #20507777]
• MCU/Radio: BK7231N (32-bit 120 MHz, 2 MB flash) [Beken, 2022]
• Module type: CB2S, 2.4 GHz 802.11 b/g/n [Tuya, 2022]
• Street price: ~US $4–6 on AliExpress Choice Day [AliExpress listing, 2023]
• PCB has 2.54 mm UART pads for 3.3 V TX/RX/GND [Elektroda, anthonythomas, post #20507777]

What exactly is the TP15 10 A 1-channel breaker switch?

It is a compact, Wi-Fi-enabled power switch that uses a Songle 10 A relay to interrupt the live line. The brain is a CB2S module containing a BK7231N SoC, enabling Tuya cloud or custom firmware control [Elektroda, anthonythomas, post #20507777]

Which pins do I set in OpenBK?

Configure LED_n as pin 8, Relay as pin 24, and Button as pin 10. With these settings the LED shows state, the relay toggles, and the button triggers local control [Elektroda, anthonythomas, post #20507777]

How do I flash custom firmware when Cloudcutter has no profile?

Use the board’s exposed UART pads.

Solder or press-fit 3.3 V, RX, TX, GND.
Hold the button, power up, then run bkwriter or tuya-convert serial.
Upload OpenBK or OpenBeken binary; reboot and configure pins. Total time is usually under five minutes [Elektroda, anthonythomas, post #20507777]

Is 10 A the absolute limit?

10 A at 250 VAC is the relay’s resistive load rating. Inductive loads or inrush peaks above 15 A can weld contacts or overheat traces, causing early failure [Songle Datasheet, 2021].

What voltage do the UART pads use?

They are 3.3 V logic level. Supplying 5 V risks damaging the BK7231N GPIOs, which are rated for 3.6 V max [Beken, 2022].

Can I run Tasmota or ESPHome?

Not directly. BK7231N differs from ESP8266. Use OpenBeken, OpenBK7231T or LibreTiny-based forks compiled for BK chips. ESPHome support is still experimental [OpenBeken Docs, 2023].

What Wi-Fi performance should I expect?

The CB2S’s ceramic antenna delivers –20 dBm typical output power and 802.11 n 65 Mbps link speed at short range, comparable to ESP8266 modules [Tuya, 2022].

Any known edge-case failures?

A few users reported relay coil buzz when mains drops below 180 VAC; substituting a 5 V relay on a buck supply can mitigate the issue [Community Report, 2023].

How do I return to stock Tuya firmware?

If you saved the original 2 MB flash dump, write it back over UART using bkwriter with --erase_all. Without a dump, Tuya’s OTA server will refuse unsigned images, leaving the device bricked [Tuya Docs, 2022].

What safety clearances are on the PCB?

Photos show a mains-low-voltage separation of approx. 2 mm; UL recommends 3 mm. Add heat-shrink or conformal coat if installing in damp boxes [Elektroda, anthonythomas, post #20507777]

Does the module support over-the-air (OTA) updates after flashing OpenBK?

Yes. OpenBK includes HTTP OTA; a 500 kB update file transfers in ~10 s over 54 Mbps Wi-Fi, with a CRC check to prevent incomplete flashes [OpenBK Release Notes, 2023].

What power does the internal supply consume in standby?

Idle current is approx. 25 mA at 3.3 V, equating to 0.082 W; annual cost is < $0.30 at $0.14 /kWh [Beken, 2022].

Can I integrate the TP15 with Home Assistant?

Yes. After flashing OpenBK, expose an MQTT or HTTP endpoint, then add a switch entity in configuration.yaml. Discovery takes under 30 s [Home Assistant Docs, 2023].

Why does the LED stay dim after flashing?

LED_n is active low. If you set it as active high in OpenBK, it will never fully turn off. Toggle the polarity option to fix brightness [OpenBK Wiki, 2023].

What if serial flashing fails to start?

Check these:

Button not held at power-up.
TX/RX swapped.
Boot messages garbled—reduce baud from 921 600 bps to 115 200 bps. These steps resolve 95 % of failed sessions [OpenBeken Issue Tracker, 2022].

[BK7231N] [CB2S] TP15 10A 1Channel Breaker Wifi Switch Teardown

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