Hi Fuzzy,
This looks like a really awesome device, and after a quick read over the datasheet, it appears to have a pretty simple TTL serial interface. From page 16 of the datasheet on the page you linked to,
NOTE!
The RX and the TX signals are at 3.3V levels. If interfacing to a host system running at
voltages greater than 3.6V levels, say 5.0Volts, then a 100 to 220 Ohms series resistor must
be inserted between the Host Tx and the μDRIVE-uSD-G1 Rx signals.
Note that the data storage is in raw format. To use FAT16/FAT32 file system so that a PC can understand the data, you would need a special library installed on the host controller, like
this one.
-HyperNerd