User’s Manual
74
Figure A-4 shows a typical timing diagram for the Rabbit 4000 microprocessor external I/O read
and write cycles.
Figure A-4. External I/O Read and Write Cycles—No Extra Wait States
NOTE:
/IOCSx
can be programmed to be active low (default) or active high.
Tadr
Tadr
External I/O Read (no extra wait states)
CLK
A[15:0]
External I/O Write (no extra wait states)
CLK
A[15:0]
/IORD
valid
T1
Tw
T1
Tw
T2
valid
T2
/BUFEN
/IOCSx
/IOWR
/BUFEN
D[7:0]
valid
Tsetup
Thold
/CSx
/IOCSx
TCSx
TIOCSx
TIORD
TBUFEN
TCSx
TIOCSx
TIORD
TBUFEN
valid
D[7:0]
/CSx
TCSx
TIOCSx
TIOWR
TCSx
TIOCSx
TIOWR
TBUFEN
TBUFEN
TDHZV
TDVHZ