Rev. 6.00, 08/04, page 73 of 628
Section 3 Exception Handling
3.1
Overview
Exception handling is performed in the H8/38024 Group, H8/38024S Group, H8/38024F-ZTAT
Group, and H8/38124 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
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 takes place as follows.
•
The CPU internal state and the registers of on-chip peripheral modules are initialized, with the
I bit of the condition code register (CCR) set to 1.
•
The PC is loaded from the reset exception handling vector address (H'0000 to H'0001), after
which the program starts executing from the address indicated in PC.
Содержание H8/38024 Series
Страница 18: ...Rev 6 00 08 04 page xviii of xxx...
Страница 30: ...Rev 6 00 08 04 page xxx of xxx...
Страница 130: ...Rev 6 00 08 04 page 100 of 628...
Страница 216: ...Rev 6 00 08 04 page 186 of 628...
Страница 416: ...Rev 6 00 08 04 page 386 of 628...
Страница 432: ...Rev 6 00 08 04 page 402 of 628...
Страница 468: ...Rev 6 00 08 04 page 438 of 628...
Страница 661: ...H8 38024 H8 38024S H8 38024F ZTAT H8 38124 Group Hardware Manual...