Datasheet

Table Of Contents
Section 6 Bus Controller
Page 138 of 846 REJ09B0140-0900 Rev. 9.00
Sep 16, 2010
H8S/2215 Group
6.6.4 Wait Control
When accessing external space, this LSI 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 T
2
state and T
3
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. 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
φ in the last T
2
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.