The "Serial Data Protocol" has three valid combinations for the start of a communication defined:
0 0 - Host Memory Read
1 0 - Host Memory Write
0 1 - Host Command
What happens though in the FT81x / BT81x if the first two bits are 1 1?
Is the byte discarded as invalid and the next byte used as actual start of the frame?
Or is the complete frame discarded as invalid?
Could 0xc0 0x00 0x00 0x00 used for cmd ACTIVE?
Could 0xc0 0x30 0x20 0x00 used to read REG_ID?
Edit: I was too curious to not try this although doing undocumented things does not yield reliable results.
I changed my host command implementation by sending out an extra byte first - unfortunately this does not work at all,
the screen stays black.
Adding a trailing byte after the host command works though, so at least these could be using 32 bit transfers.
My "issue" is with the 24 bits for Host Memory Read/Write though.
