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Section 3 Exception Handling
Rev. 6.00 Sep 12, 2006 page 59 of 526
REJ09B0326-0600
Section 3 Exception Handling
3.1 Overview
Exception handling is performed in the H8/3644 Group when a reset or interrupt occurs. Table 3.1
shows the priorities of these two types of exception handling.
Table 3.1
Exception Handling Types and Priorities
Priority
Exception Source
Time of Start of Exception Handling
High
Reset
Exception handling starts as soon as the reset state is cleared
Low
Interrupt
When an interrupt is requested, exception handling starts after
execution of the present instruction or the exception handling
in progress is completed
3.2 Reset
3.2.1 Overview
A reset is the highest-priority exception. The internal state of the CPU and the registers of the on-
chip peripheral modules are initialized.
3.2.2 Reset
Sequence
Reset by
RES
RES
RES
RES
Pin:
As soon as the RES pin goes low, all processing is stopped and the chip enters
the reset state.
To make sure the chip is reset properly, observe the following precautions.
•
At power on: Hold the
RES
pin low until the clock pulse generator output stabilizes.
•
Resetting during operation: Hold the
RES
pin low for at least 10 system clock cycles.
Reset exception handling begins when the
RES
pin is held low for a given period, then returned to
the high level.
Содержание F-ZTAT H8/3642A Series
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Страница 188: ...Section 6 ROM Rev 6 00 Sep 12 2006 page 166 of 526 REJ09B0326 0600 ...
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Страница 446: ...Section 13 Electrical Characteristics Rev 6 00 Sep 12 2006 page 424 of 526 REJ09B0326 0600 ...