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6.6.4
Wait Control
When accessing external space, this LSI can extend the bus cycle by inserting one or more wait
states (Tw). There are two ways of inserting wait states: program wait insertion and pin wait
insertion using the WAIT pin.
(1) Program Wait Insertion
From 0 to 3 wait states can be inserted automatically between the T
individual area basis in 3-state access space, according to the settings of WCRH and WCRL.
(2) Pin Wait Insertion
Setting the WAITE bit in BCRH to 1 enables wait insertion by means of the WAIT pin. When
external space is accessed in this state, program wait insertion is first carried out according to
the settings in WCRH and WCRL. Then, if the WAIT pin is low at the falling edge of ø in the
last T
or T
state, a T
2
W
until it goes high.
Rev. 3.0, 10/02, page 128 of 686
state is inserted. If the WAIT pin is held low, T
W
state and T
state on an
2
3
states are inserted
W
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