Unknown MCU with one-wire programming interface on pin PB3

[gashtaan]

I'm trying to identify MCU (SoC with 2.4GHz RF) in QFN32 package, probably a Chinese one. There is a programming pin header with 3 pins: 3.3V, GND and mysterious PB3. Anyone has a clue what MCU has one-wire programming interface on PB3 pin?

[WarkARI]

My first guess would be from this family (https://www.telink-semi.com/products/bluetooth-le/tlsr825x)
Given the 3 wire SWS/SWire is usually labelled as PB3.
Have you traced it to a pin on the QFN32? That would narrow it right down.

[gashtaan]

My first guess would be from this family (https://www.telink-semi.com/products/bluetooth-le/tlsr825x)
Given the 3 wire SWS/SWire is usually labelled as PB3.
Have you traced it to a pin on the QFN32? That would narrow it right down.

I've considered Telink's ICs before, but I don't recall ever seeing SWS share the PB3 pin. But thanks for the hint, I'll try if it communicates as SWS on that pin.
Update: I tried it, but I got no response to SWS commands.

PB3 is connected to pin 22. Other pins that could shed some light to it are pin 16 as antenna output, and pins 17, 18 where 24MHz crystal is connected. So far I was not able to find anything that matches this pinout.