I've managed to compile a working firmware with this config: https://github.com/gleber/qmk_firmware/commit/54078ec73c0ff2bd01984242f748a837c1954d03
This isn't tested much, just the basics: keys and split setup. LED, bootloader magic key and any other features are not yet implemented. Tested only the Miryoku layout so far.
I've disassembled it and found a few things.
Back of one of the sides looks like this:
A more close up photo of the chip shows some STM32 chip:
If you decode the QR code it gives you a short link to what seem to be JLC PCB page about this specific PCB:
- right: https://m-9.cn/2kx9vqhz04xv
- left: https://m-9.cn/2kx9vqu40dft
It includes product name 【X.Tips】X7S小分体键盘_-_V2.0_【热插拔】PCB-X7S-V2-R__20240726163326 which translates with Google Translate to 【X.Tips】X7S small split keyboard_-_V2.0_【Hot plug】PCB-X7S-V2-R__20240726163326
And these schematics images for the right side:
and for the left side:
Attached via-x7.json file was sent to one of the buyers by the seller. It works for my keyboard.
Keys are connected directly to the chip. I am using this pinout of the chip:
https://robiz.net/image/cache/data/entegre/stm/stm32f103/stm32f103_07-500x500.jpg
And the left side keys are connected like this: