Singxer Q1 – USB Digital Interface Board – XU208 Chip (FSx-schematics)
found by chance this XMOS USB-interface board; is well known->https://kitsunehifi.com/product/singxer-q1-digital-interface-board-xu208
54€ at Ebay..->LINK
so far so good, looks like normal XMOS-USB-bridges..
but interesting are the schematics to it and finally some (perhaps) information about the FS0, FS1, FS2, Mute and DSD_ON-pins..(they are nearly on every XMOS-USB-board)..
I2S socket Output Signal Description:
1 , the MUTE is high mute; DSD_ON is high DSD data stream;
2 , all the electricity an average of LVCMOS, voltage of 3.3V ;
3 , 3.3+ output power, low output current 50mA;
4 , the MCLK output 22.5792Mhz or 24.576Mhz clock;
5 , FS0, FS1, FS2 sampling rate indicator level, FS3 not;
so, the question is, are they frequency-„switches“ or, what they´ve written, „sampling rate indicator(s)“..
(but beware,they also say:“Please note, schematics and firmware (XMOS) are our own development, not the public version“)
don´t know at present, but if they are „sampling rate indicators“ you can connect some LEDs (or similar) to them and then you have your desired „sample rate indicator“ and can display it via a tftlcd or something..(but still unclear about it here; will post here any other info)