p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 108

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 4 Exception Handling
4.3.2
If an interrupt is accepted immediately after a reset and 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 a reset, make sure that this instruction
initializes the SP (example: MOV.L #xx: 32, SP).
4.3.3
After a reset is cancelled, the module stop control registers (MSTPCRH, MSTPCRL, MSTPCRA,
and MSTPCRB) are initialized, and all modules except the DTC operate in module stop mode.
Therefore, the registers of on-chip peripheral modules cannot be read from or written to. To read
from and write to these registers, clear module stop mode. For details on module stop mode, see
section 22, Power-Down Modes.
Rev. 1.00 Sep. 21, 2006 Page 70 of 658
REJ09B0310-0100
φ
(1) Reset exception handling vector address (1) U = H'000000 (1) L = H'000002
(2) Start address (contents of reset exception handling vector address)
(3) Start address ((3) = (2)U + (2)L)
(4) First program instruction
Interrupts Immediately after Reset
On-Chip Peripheral Modules after Reset is Cancelled
RES
Internal address bus
Internal read signal
Internal write signal
Internal data bus
Figure 4.1 Reset Sequence (Mode 2)
(1) U
(2)
Vector
fetch
U
High
(2)
L
(1) L
processing
Internal
program instruction
Prefetch of first
(3)
(4)