Talking about standalone systems always brings me around to keyboards and mice and the difficulty with interfacing them since PS/2 is getting harder and harder to find. Although I use the PS/2 protocol that some devices support I haven't used the old style PS/2 connectors for many years now and prefer to use the standard USB socket for direct connection rather than the passive and therefore redundant PS/2 "adaptor".
But that got me to thinking about implementing HID USB or even programming a small chip to support HID USB back to serial or I2C rather than PS/2 perhaps. Anyway, thinking some more I tried to find if Logitech unifying receiver chips were available even and it seems that they use Nordic nRF24L01+ chips + SOC.
So on the off chance that I can hack the protocol I will hookup the nRF24L to the Prop and interact with the device via Tachyon. Nothing might come of it but if I do make it work it would be a wonderful way to interface modern keyboards and mice and even combos such as the K400r which I also use.
Here's a link to some stuff on hackaday