Table of Contents
Advertisement
7.4.5
Wait Control
When accessing external space, the H8S/2633 Series can extend the bus cycle by inserting one or
more wait states (T
). There are two ways of inserting wait states: program wait insertion and pin
w
wait insertion using the WAIT pin.
Program Wait Insertion
From 0 to 3 wait states can be inserted automatically between the T
state and T
state on an
2
3
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 T
or T
state, a T
state is inserted. If the
2
w
w
WAIT pin is held low, T
states are inserted until it goes high.
w
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.
204
Advertisement
Table of Contents
