Designing Hardware for QuickUSB
Unused I/O Pins
Some I/O pins are reserved for future use and may be activated by a new
version of the module or a new firmware release. Therefore, you must not
connect unused QuickUSB I/O pins to any signals or power supplies. DO NOT
DIRECTLY GROUND UNUSED QUICKUSB I/O PINS IN YOUR CIRCUIT. You may
use a 10k resistor to tie unused pins to a known level, but do not connect them
directly.
Default I/O State
With QuickUSB Library (including firmware) v2.11 and above, QuickUSB
supports non-volatile I/O pin default settings. The default settings are
programmed and read using the QuickUsbWriteDefault and
QuickUsbReadDefault functions respectively.
High Speed Parallel Port
The High-Speed parallel port is a truly outstanding feature of the QuickUSB
module. It is the fastest connection on the QuickUSB module and can transfer
very large blocks of data to and from your device with ease. It provides both
master and slave mode transfers with several types of transfer handshaking
models.
Overview
The high-speed parallel port (HSPP) is an 8 or 16-bit port that is used to transfer
high-speed data between the host PC and your device. The WORDWIDE setting
controls the data element width. If WORDWIDE = 1, the transfers are 16-bits
wide and if 0, 8-bits wide. For more information about WORDWIDE, see the
setting in the ‘Settings’ section of this document. If the
HSPP is in 8-bit mode, the upper 8 bits may be used as general purpose I/O.
In addition, there is a 9-bit address bus which increments each time a data
element is transferred. The address bus can be set to a fixed address to allow
multiple writes to the same address. The address bus can also be disabled and
the address bus bits reused as general purpose I/O. See the
setting in the ‘Settings’ section of this manual for
more information
There are two modes of HSPP operation, master and slave. The HSPP mode is
automatically selected by the QuickUSB firmware, but it may be changed at any
time using the
setting. Typically, your hardware will be
configured for either master or slave mode and the requirements of your
application will determine which mode is best for you.
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Unused I/O Pins