May we check what DS90CF386 RXOUT23(RES) pin function is?

"RES" means "reserved". Tables 2 and 3 say "general purpose", which means that this bit has no predefined meaning.

Hi Chen,

Clemens is correct. The reserved pin is not typically used for OpenLDI bit-mapping, as only 27 bits are needed for transmission (24 bits for RGB and 3 bits for control information). This bit (RXOUT23) can be used for some other general-purpose function, or it can be left unconnected.

Regards,

Michael