HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 135

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

4.2.3
If an interrupt is accepted after a reset but before the stack pointer (SP) is initialized, the PC and
CCR will not be saved correctly, leading to a program crash. To prevent this, all interrupt requests,
including NMI, are disabled immediately after a reset. Since the first instruction of a program is
always executed immediately after the reset state ends, make sure that this instruction initializes
the stack pointer (example: MOV.L #xx:32, SP).
4.2.4
After reset release, MSTPCR is initialized to H'3FFF and all modules except the DMAC * and
DTC enter module stop mode. Consequently, on-chip supporting module registers cannot be read
or written to. Register reading and writing is enabled when module stop mode is exited.
Note: * The DMAC is not supported in the H8S/2321.
RES
Address bus
RD
HWR, LWR
D
(1), (3) Reset exception handling vector address ((1) = H'000000, (3) = H'000002)
(2), (4) Start address (contents of reset exception vector address)
(5)
(6)
Note: * 3 program wait states are inserted.
15
Interrupts after Reset
State of On-Chip Supporting Modules after Reset Release
to D
φ
0
Start address ((5) = (2), (4))
First program instruction
Figure 4.2 Reset Sequence (Mode 4)
*
(1)
Vector fetch
(2)
Rev.6.00 Sep. 27, 2007 Page 105 of 1268
High
*
(3)
Internal
processing
(4)
Section 4 Exception Handling
Prefetch of first
program instruction
(5)
*
REJ09B0220-0600
(6)