HD6412332 RENESAS [Renesas Technology Corp], HD6412332 Datasheet - Page 195

• Manufacturer Part Number: HD6412332
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 6 Bus Controller
6.4.5
Wait Control
When accessing external space, the chip 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 wait
w
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 in
3
WCRH and WCRL.
Pin Wait Insertion: Setting the WAITE bit in BCRL to 1 enables wait input by means of the
WAIT pin. When external space is accessed in this state, a program wait is first inserted in
accordance with the settings in WCRH and WCRL. Then, if the WAIT pin is low at the falling
state is inserted. If the WAIT pin is held low, T
edge of φ in the last T
or T
state, another T
2
w
w
w
states are inserted 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. The WAITPS bit can be used to change the WAIT
input pin from P8
to P5
. To make this change, select the input pin with the WAITPS bit, then set
6
3
the WAITE bit.
Figure 6.14 shows an example of wait state insertion timing.
Rev.4.00 Sep. 07, 2007 Page 165 of 1210
REJ09B0245-0400