Datasheet

Table Of Contents
Section 3 Exception Handling
Rev. 2.00 Jul. 04, 2007 Page 50 of 692
REJ09B0309-0200
Vector fetch
Internal
address bus
Internal read
signal
Internal write
signal
Internal data
bus (16 bits)
RES
Internal
processing
Prefetch of
first program
instruction
φ
(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
(6) Initial program instruction
(1) (3) (5)
(2) (4) (6)
Figure 3.1 Reset Exception Handling Sequence
3.2.2 Interrupt Immediately after Reset
Immediately after a reset, if an interrupt is accepted before the stack pointer (SP) is initialized, PC
and CCR will not be pushed onto the stack correctly, resulting in program runaway. To prevent
this, immediately after reset exception handling all interrupts are masked. For this reason, the
initial program instruction is always executed immediately after a reset. This instruction should
initialize the stack pointer (e.g. MOV.L #xx: 32, SP).