Designing Hardware for QuickUSB
Synchronous Slave FIFO I/O Model
This I/O Model performs all transfers synchronously with IFCLK. This model is
configured by setting the
bits IFCFG (bits 0-1) to ‘11’ to
go to Slave FIFO Mode and ASYNC (bit 3) to ‘1’ to make all transactions
synchronous to IFCLK.
IFCLK
IFCLK
t
XFD
nSLOE
PA2
Name
Pin
Read Cycle
t
OEon
t
IFCLK
nSLRD
RDY0
nSLWR
RDY1
FLAGC (nEMPTY) CTL2
FLAGB (nFULL) CTL1
DATA
PB
…
t
OEoff
t
XFLG
t
SRD
t
RDH
FIFOADR[1:0]
PA5:PA4
t
SFA
t
FAH
t
FAFLG
X
X
t
FAFD
t
SRD
t
RDH
t
SFA
t
SRD
t
RDH
X
t
FAH
t
FAFD
t
FAFLG
X
X
X
Z
Data0
Data1
Data2
Data3
Data[N-1
]
Data[N]
00
X
Z
X
00
nPKTEND
PA6
Signifies QuickUSB Write to the Data Bus
nSLCS
PA7
IFCLK
IFCLK
t
XFLG
nSLOE
PA2
Name
Pin
Z
Write Cycle
Z
t
SFD
t
IFCLK
nSLRD
RDY0
nSLWR
RDY1
FLAGC (nEMPTY) CTL2
FLAGB (nFULL) CTL1
DATA
PB
Data0
Data[N-1]
Data[N]
t
FDH
t
SWR
t
WRH
Data[N-2]
Data2
Data1
Data3
Data4 …
FIFOADR[1:0]
PA5:PA4
10
X
X
t
SFA
t
FAH
t
FAFLG
t
FAH
X
X
X
X
t
FAFLG
nPKTEND
PA6
10
t
SPE
t
PEH
nSLCS
PA7
Signifies QuickUSB Read from the Data Bus
Figure 1 - Synchronous Slave FIFO I/O Timing Diagrams
High Speed Parallel Port
17