Rev.6.00 Oct.28.2004 page 75
of 1016
REJ09B0138-0600H
4.2.3
Reset Sequence
The H8S/2357 Group enters the reset state when the
RES
pin goes low.
To ensure that the H8S/2357 Group is reset, hold the
RES
pin low for at least 20 ms at power-up. To reset the H8S/2357
Group during operation, hold the
RES
pin low for at least 20 states.
When the
RES
pin goes high after being held low for the necessary time, the H8S/2357 Group starts reset exception
handling as follows:
1. The internal state of the CPU and the registers of the on-chip supporting modules are initialized, the T bit is cleared to
0 in EXR, and the I bit is set to 1 in EXR and CCR.
2. The reset exception handling vector address is read and transferred to the PC, and program execution starts from the
address indicated by the PC.
Figure 4-2 show examples of the reset sequence.
Address bus
Vector fetch
Internal
processing
Prefetch of first
program instruction
(1) (3) Reset exception handling vector address ((1) = H'000000, (3) = H'000002)
(2) (4) Start address (contents of reset exception handling vector address)
(5) Start address ((5) = (2) (4))
(6) First program instruction
ø
RES
(1)
(5)
High
(2)
(4)
(3)
(6)
RD
HWR, LWR
D
15
to D
0
*
Note:
*
3 program wait states are inserted.
*
*
Figure 4-2 Reset Sequence (Mode 4)
Содержание ZTAT H8S/2357F
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Страница 1047: ...H8S 2357 Group H8S 2357F ZTATTM H8S 2398F ZTATTM Hardware Manual 2 6 2 Ote machi Chiyoda ku Tokyo 100 0004 Japan...