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CHAPTER 3 CPU AND CONTROL UNITS
3.10.1
Reset Levels
The reset operations of the MB91319 are classified into two levels, each of which has
different causes and initialization operations. This section describes these reset levels.
■ Settings Initialization Reset (INIT)
The highest-level reset, which initializes all settings, is called a settings initialization reset (INIT).
A settings initialization reset (INIT) mainly performs the following initialization:
❍ Items initialized in a settings initialization reset (INIT)
•
Device operation mode (bus mode and external bus width settings)
•
All internal clock settings (clock source selection, PLL control, and divide-by setting)
•
All settings on external bus CS0 area
•
All settings on pin statuses other than the above settings
•
All sections initialized by an operation initialization reset (RST)
For more information, see the description of each of these functions.
Note:
After power-on, be sure to apply the settings initialization reset (INIT) at the INIT pin.
■ Operation Initialization Reset (RST)
A normal-level reset that initializes the operation of a program is called an operation initialization
reset (RST).
If a settings initialization reset (INIT) occurs, an operation initialization reset (RST) also occurs.
An operation initialization reset (RST) mainly initializes the following items:
❍ Items initialized by an operation initialization reset (RST)
•
Program operation
•
CPU and internal buses
•
Register settings of peripheral circuits
•
I/O port settings
•
All CS0 area settings of external buses
For more information, see the description of each of these functions.
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