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6.4.5
Wait Control
When accessing external space, the H8S/2319 and H8S/2318 Groups can extend the bus cycle by
inserting one or more wait states (T
). There are two ways of inserting wait states: program wait
w
insertion and pin wait insertion using the WAIT pin.
Program Wait Insertion: From 0 to 3 wait states can be inserted automatically between the T
2
state and T
state on an individual area basis in 3-state access space, according to the settings of
3
WCRH and WCRL.
Pin Wait Insertion: Setting the WAITE bit in BCRL 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
state is inserted. If the WAIT pin is held low, T
φ in the last T
or T
state, a T
states are
2
w
w
w
inserted until it goes high.
This is useful when inserting four or more T
states, or when changing the number of T
states for
w
w
different external devices.
The WAITE bit setting applies to all areas.
Rev. 5.00, 12/03, page 168 of 1088
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