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Pin Wait Insertion: Setting the WAITE bit in BCR to 1 enables wait insertion by means of the
WAIT pin. When external space is accessed in this state, a program wait is first inserted. If the
WAIT pin is low at the falling edge of φ in the last T
the WAIT pin is held low, T
This is useful when inserting four or more T
different external devices.
The WAITE bit setting applies to all areas.
Figure 6.17 shows an example of the timing for insertion of one program wait state in 3-state
space.
Read access
Write access
states are inserted until it goes high.
W
φ
WAIT
Address bus
AS
RD
Data bus
HWR, LWR
Data bus
indicates the timing of WAIT pin sampling.
Note:
Figure 6.17 Example of Wait State Insertion Timing
or T
state, another T
2
W
states, or when changing the number of T
W
Inserted
by program wait Inserted by WAIT pin
T
T
T
1
2
w
Write data
state is inserted. If
W
T
T
T
w
w
3
Read data
states for
W
153
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