HD64F3028F25 Datasheet, PDF (181/925 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Pin Wait Insertion: Setting the WAITE bit in BCR to 1 enables wait insertion by means of the
WAIT pin. When external space is accessed in this state, a program wait is first inserted. If the
WAIT pin is low at the falling edge of φ in the last T₂ or T_W state, another 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. Pin waits cannot be inserted in DRAM space.
Figure 6.17 shows an example of the timing for insertion of one program wait state in 3-state
space.
Inserted
by program wait Inserted by WAIT pin
T1
T2
Tw
Tw
Tw
T3
φ
WAIT
Address bus
Read access
AS
RD
Data bus
Read data
Write access
HWR, LWR
Data bus
Write data
Note: indicates the timing of WAIT pin sampling.
Figure 6.17 Example of Wait State Insertion Timing
Rev. 2.00, 09/03, page 149 of 890