Information Technology Reference
In-Depth Information
Figure 11-3: The USBwiz-OEM board enables just about any microcontroller to
access USB drives and flash-memory cards.
The USBwiz-OEM (Figure 11-3) is a circuit board that contains a USBwiz,
an ISP1160, a MultiMediaCard/SD-card connector, and dual USB connec-
tors for attaching devices. The USBwiz uses a +3.3V supply. The USB-
wiz-OEM board requires a +5V supply and has an on-board 3.3V regulator.
Microcontrollers can communicate with the USBwiz using an asynchronous
serial interface, SPI, or an I 2 C bus. The USBwiz responds to commands sent
in text mode, with commands and values sent as ANSI text, or in framed
mode, with commands and values sent as binary values. In text mode, this
command reads E8h bytes from a file opened with handle 0:
RF #0 E8
This command prepares the USBwiz to receive 10h bytes to be written to a
file opened with handle 0Bh:
WF #B 10
On receiving the command above, the USBwiz returns a prompt character
( " ). The microcontroller writes the 16 bytes to the USBwiz, and the USBwiz
returns a prompt character ( " ) to indicate that the data was received. Framed
mode also supports reading and writing to sectors in the storage media. File
commands enable opening, closing, reading, writing to, and deleting a file.
Directory commands enable creating, changing, listing, and erasing a direc-
tory.
 
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