HD64F2357VF13 Datasheet, PDF (166/1049 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

6.4.5 Wait Control
When accessing external space, the H8S/2357 Group can extend the bus cycle by inserting one or more wait states (T_w).
There are two ways of inserting wait states: program wait insertion and pin wait insertion using the WAIT pin.
Program Wait Insertion: From 0 to 3 wait states can be inserted automatically between the T₂ state and T₃ state on an
individual area basis in 3-state access space, according to the settings of WCRH and WCRL.
Pin Wait Insertion: Setting the WAITE bit in BCRL to 1 enables wait insertion by means of the WAIT pin. 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 T₂ or T_w state, a T_w state is inserted. If the WAIT pin is held low, T_w states are inserted until it goes
high.
This is useful when inserting four or more T_w states, or when changing the number of T_w states for different external
devices.
The WAITE bit setting applies to all areas.
Rev.6.00 Oct.28.2004 page 136 of 1016
REJ09B0138-0600H