Identifying an MCU with touch sense inputs

[betwixt]

I have a "Smart Life" branded domestic dual light switch with touch sensors, WiFi and Bluetooth features. I'm hoping to remove the WB3S micro module and replace it with an ESP8266 which is almost pin compatible. My intention is to integrate it with a home control system using MQTT instead of its original Alexa based control and writing new firmware is no problem for me but the touch sensing is done by a second IC on the board and I'm having difficulty identifying it. It seems to be an MCU with internal clock and at least three touch sensing inputs, if I can work out how it communicates with the WB3S I'm sure I can interface and retain touch control in my new code.

Does anyone know what it is, package is SOIC-16 and the pin outs based on reverse engineering the track layout seems to be:
1, 2 & 3 (possibly 4) are touch inputs,
5 goes to a pad marked "TX" so it is probably a UART output,
6 - not connected on the PCB
7 goes to a pad marked "RX" so it is probably a UART input,
8 is VSS (ground)
9 goes to an unfitted module, possibly a 433MHz receiver
10 drives a buzzer via a transistor
11 goes to that unfitted module
12 is VCC (3.3V)
13 is unconnected
14 goes to the WB3S so it is some kind of data link
15 also goes to the WB3S
16 is unconnected

I may have to hook up a logic analyzer but unfortunately the PCB is not isolated from the incoming mains so I'm asking before going to the trouble of wiring up an isolating transformer as I do not have one to hand at the moment. The IC has absolutely no marking on it at all and there are no clues on the WB3S pins it connects to. An MCU with supply on pins 8 and 12 is unusual and may be a clue.

Brian.

 

[betwixt]

If anyone else tries this, it isn't an MCU at all. After hours of searching I found and confirmed it is a WTC6106BSI made by WincomTech. It is a six input touch to pulse output interface.

Brian.

 

[stenzer]

Hi Brian,

out of curiosity, does it looks like that the package marking has been removed on purpose?
Search results including pictures show an (engraved?) pakage marking e.g. on aliexpress.

BR

 

[betwixt]

It is absolutely devoid of any markings and shows no trace of having been sanded, it's as though the device manufacturer (Yagusmart) had ordered them without identifying features.

I wrote new code for a ESP8266 today, tested it in a development board then did the transplant but it isn't working. The ESP8266 needs pin GPIO0 to be high at boot to start normal operation and on the PCB it is connected through a 1K resistor and LED to the 3.3V supply so I suspect the voltage isn't high enough to get it running. It's late at night here so I'll continue experiments tomorrow.

Brian.