About grip communication protocol

[Ayanami]

Hi,

I have SCG Premium Grips for GNX, and I'm going to make a forcefeedback pedestal based on STM32 using them.
I have known that the grip connect GNX via UART, but is there any defination available about the connection and communication? How can I read whether the bottom is pressed and control the LEDs?
Any reply helps and appriciated.

Ayanami X.