![Image](https://kephost.com/images/2017/06/20/ws_00.th.png)
With the 64x57mm size of its back, it will not fit in neither 65mm nor 80mm diameter in-wall socket. Maybe in external mounting box will do...
![Image](https://kephost.com/images/2017/06/20/ws_01.th.png)
It has an app named Yewelink, tried with it, sniffed the communication with Wireshark: after a short check-in to taobao.com the device logged in to the Amazon cloud. Also see some kind of MQTT communication, but i want to use my own server. (I do not like cloud based solutions)
So i opened it, found an ESP8266MOD inside.
![Image](https://kephost.com/images/2017/06/20/ws_11.th.jpg)
Found the RX, TX, GND on the 2x7 pin JP1, and a possible 3.3V location. (orange cable connected on picture)
![Image](https://kephost.com/images/2017/06/20/ws_pin.th.jpg)
![Image](https://kephost.com/images/2017/06/20/ws_10.th.jpg)
On ESP8266 the GND has to be connected to GPIO0 at startup, than disconnect, after that it can be flashed with esptool (dio, 4mbit...)
I flashed with ESPEasy R120, but unfortunately this model does not have connected any relay to any GPIO of the ESP. Only ESP8266 RX/TX connected to a PIC16F1829 and the PIC is the main controller. Added Ser2Net device and try to listen packets. I hoped it will similar to Sonoff Dual, but i have no luck, packets were really different.
Fortunately i have found "Serial Communication Protocol Standard Edition" at https://docs.tuya.com/en/download/
I have created a working plugin and i added it to the Software section of this forum.