[BK7231N/CB2S] Tuya smart dual socket 20A - teardown, CB2S, BL0937

This product is one of the unbranded Tuya dual plug devices. It doesn’t seem to have any special external differences, but unlike other products, it has no screws. The case can be opened by prying apart the top gap, and adhesive is required to reattach it.



Unlike other products, the plug PCB can be removed from the case, allowing the firmware to be changed directly via UART. Cloudcutter is not supported.

OBK UART flash tool: https://github.com/openshwprojects/BK7231GUIFlashTool



It uses the CB2S module, but the version included has the rear silkscreen misprinted, so it must be read in reverse. You can refer to Tuya’s official CB2S documentation. since the RX and TX are being used on different pins, when connecting via UART you need to remove the solder on the RX and TX pins so that the CB2S and the main PCB are isolated, in order to read and write the firmware.



The power measurement chip used is the BL0937, and since the CB2S has very few available GPIO pins, the sel pin is unusually connected to the ADC.  

Pins:


OBK template:




ESPhome YAML

Thank you for sharing! I've added some more information, including OBK JSON, so we can feature this device on our supported devices list:
https://openbekeniot.github.io/webapp/devicesList.html
We're already at 807 devices so far there, maybe we can reach 900 in the next year, who knows...

Feel free to add teardowns of any other devices you have, thanks.