The Universal Serial Interface for the Amstrad CPC (USIFAC), currently in version 2 (Styled USIFAC II), is a modern serial interface based around a PIC microcontroller designed and built by ikonsgr from the CPCWIKI Forums.
The only chip on the board is the 18F47Q10 PIC. The PIC software is written in Great Cow Basic and has been released by ikonsgr.
Details of hardware, software and manuals are available here: https://www.dropbox.com/sh/ezzga2dppm6jlm7/AACwFC_rv2QatWh_ndKc9fhma?dl=0
The board allows for TTL serial output and connection to a USB SD card module as well as a ESP8266 WIFI module. The board has been used for many purposes including running games from SD Card, MIDI, RS232 and accessing online BBS.