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Pin Wait Mode 1: In all accesses to external three-state-access areas, the number of wait states
) selected by bits WC1 and WC0 are inserted. If the WAIT pin is low at the fall of the system
(T
W
clock (ø) in the last of these wait states, an additional wait state is inserted. If the WAIT pin
remains low, wait states continue to be inserted until the WAIT signal goes high.
Pin wait mode 1 is useful for inserting four or more wait states, or for inserting different numbers
of wait states for different external devices.
If the wait count is 0, this mode operates in the same way as pin wait mode 0.
Figure 6-6 shows the timing when the wait count is 1 (WC1 = 0, WC0 = 1) and one additional
wait state is inserted by WAIT input.
ø
WAIT
pin
Address bus
AS
RD
Read
access
Data bus
WR
Write
access
Data bus
Note:
*
Arrows indicate time of sampling of the
Inserted by
wait count
T
T
T
1
2
W
*
External address
Write data
Write data
WAIT
pin.
Figure 6-6 Pin Wait Mode 1
113
Inserted by
WAIT
signal
T
T
W
3
*
Read data
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