Designing Hardware for QuickUSB
Full Handshake I/O Model
The full handshake I/O model is ideal for connecting a device that has a very
slow or variable transfer time. The module checks the state of the READY signal
before each state transition and thereby guarantees that the module and target
will be properly synchronized at all times.
This I/O model is implemented in the QuickUSB firmware file
‘quickusb-fullhs vX.XX.qusb’ where X.XX is the firmware version number.
Command Transfers
IFCLK
IFCLK
X
Data[N]
Z
t
DAH
t
SGD
CMD_DATA
CTL0
REN
CTL1
WEN
CTL2
nREN
CTL3
nWEN
CTL4
RDYTST
CTL5
GPIFADR
GPIFADR
FD
PB, PD
Name
Pin
Z
Z
X
Data[N]
t
XGD
Z
Addr[N]
Read Cycle
Write Cycle
READY
RDY0
t
XCTL
t
SRY
t
XCTL
Addr[N+1]
X
Addr[N]
t
XCTL
t
RYH
Addr[N+1]
X
t
SGA
t
SRY
t
RYH
t
XCTL
t
SRY
t
RYH
t
SRY
t
RYH
t
SGA
Signifies QuickUSB Read
from the Data Bus
Signifies QuickUSB Write
to the Data Bus
t
XCTL
t
XCTL
Data Transfers
IFCLK
IFCLK
Addr0
X
t
DAH
t
SGD
CMD_DATA
CTL0
REN
CTL1
WEN
CTL2
nREN
CTL3
nWEN
CTL4
RDYTST
CTL5
GPIFADR
GPIFADR
FD
PB, PD
Name
Pin
Z
Data0
Read Cycle
X
Z
t
SGA
READY
RDY0
Addr1
Data1
Addr[N]
Data[N]
Z
Z
t
SRY
t
RYH
…
Addr[N+1]
…
t
XCTL
t
XCTL
t
XCTL
t
IFCLK
t
SRY
t
RYH
Signifies QuickUSB Read from the Data Bus
Full Speed, Byte Wide: N = 63
High Speed, Byte Wide: N = 511
Full Speed, Word Wide: N = 31
High Speed, Word Wide: N=255
IFCLK
IFCLK
Addr0
X
t
XGD
CMD_DATA
CTL0
REN
CTL1
WEN
CTL2
nREN
CTL3
nWEN
CTL4
RDYTST
CTL5
GPIFADR
GPIFADR
FD
PB, PD
Name
Pin
Z
Data0
Write Cycle
X
Z
t
SGA
READY
RDY0
Addr1
Addr[N]
Z
Z
t
SRY
t
RYH
Addr[N+1]
t
XCTL
t
XCTL
t
IFCLK
Data[N]
t
SRY
t
RYH
Data1
t
XGD
t
XCTL
…
Signifies QuickUSB Write to the Data Bus
Full Speed, Byte Wide: N = 63
High Speed, Byte Wide: N = 511
Full Speed, Word Wide: N = 31
High Speed, Word Wide: N=255
High Speed Parallel Port
11