h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 118

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 4 Exception Handling
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).
Rev. 5.00 Sep 22, 2005 page 92 of 1136
REJ09B0257-0500
(1) (3) Reset exception handling vector address (when reset, (1) = H'000000,
(2) (4) Start address (contents of reset exception handling vector address)
(5)
(6)
Note: * 3 program wait states are inserted.
Interrupts after Reset
RES
Address bus
RD
HWR, LWR
D15 to D0
(3) = H'000002)
Start address ((5) = (2) (4))
First program instruction
Figure 4.3 Reset Sequence (Mode 4)
(1)
*
(2)
Vector
fetch
High
*
processing
(3)
Internal
(4)
Prefetch of first program
instruction
*
(5)
(6)