Designing Hardware for QuickUSB
Simple I/O Model
This I/O model performs transfers without regard to the readiness of the target
hardware. This model is suitable for hardware that is always ready and that can
transfer data as fast as the host can deliver it. This is the fastest QuickUSB I/O
model available.
The Simple I/O model is backwards compatible with all default QuickUSB
firmware files.
This I/O model is implemented in the QuickUSB firmware file
‘quickusb-simple vX.XX.qusb’ where X.XX is the firmware version number.
The Simple I/O model is designed to provide the highest possible data rate that
the hardware can provide.
AS A RESULT, THERE ARE CERTAIN INVALID TRANSFER LENGTHS THAT MAY
RESULT IN A FATAL SOFTWARE ERROR WHICH MAY CRASH YOUR COMPUTER.
The simplest valid transfer length calculation is to request data transfer lengths
in multiples of 512 bytes for Hi-Speed mode or 64 bytes for Full-Speed mode.
For applications that cannot use this simplified method, see the Notes section
below.
Command Transfers
IFCLK
IFCLK
Addr0
X
t
XGD
CMD_DATA
CTL0
REN
CTL1
WEN
CTL2
nREN
CTL3
nWEN
CTL4
nOE
CTL5
GPIFADR
GPIFADR
FD
PB, PD
Name
Pin
Z
Data0
Write Cycle
X
Z
nEMPTY
RDY0
nFULL
RDY1
X
X
t
IFCLK
t
XCTL
t
SGA
Signifies QuickUSB Write to
the Data Bus
t
XCTL
t
XCTL
IFCLK
IFCLK
Addr0
X
t
DAH
CMD_DATA
CTL0
REN
CTL1
WEN
CTL2
nREN
CTL3
nWEN
CTL4
nOE
CTL5
GPIFADR
GPIFADR
FD
PB, PD
Name
Pin
Z
Data0
Read Cycle
X
Z
nEMPTY
RDY0
nFULL
RDY1
X
X
t
IFCLK
t
XCTL
t
SGD
t
SGA
Signifies QuickUSB Read
from the Data Bus
t
XCTL
t
XCTL
High Speed Parallel Port
7