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12-3
SPECIAL OPERATING MODES
12.2 REDUCING POWER CONSUMPTION
Each power-saving mode conserves power by disabling portions of the internal clock circuitry
(Figure 12-1 and Figure 12-2). The following paragraphs describe each mode in detail.
INT_MASK1
0013H
Interrupt Mask 1
Bits 5 and 6 of this register enable and disable (mask) the
external interrupts, EXTINT2 and EXTINT3.
INT_PEND
0009H
Interrupt Pending
Bits 3 and 4 of this register are set to indicate a pending external
interrupt, EXTINT0 and EXTINT1.
INT_PEND1
0012H
Interrupt Pending 1
Bits 5 and 6 of this register are set to indicate a pending external
interrupt, EXTINT2 and EXTINT3.
P2_DIR
P3_DIR
1FD3H
1FDAH
Port
x
Direction
Each bit of P
x
_DIR controls the direction of the corresponding pin.
Clearing a bit configures a pin as a complementary output; setting
a bit configures a pin as an input or open-drain output. (Open-
drain outputs require external pull-ups.)
P2_MODE
P3_MODE
1FD1H
1FD8H
Port
x
Mode
Each bit of P
x
_MODE controls whether the corresponding pin
functions as a standard I/O port pin or as a special-function
signal. Setting a bit configures a pin as a special-function signal;
clearing a bit configures a pin as a standard I/O port pin.
P2_REG
P3_REG
1FD5H
1FDCH
Port
x
Data Output
For an input, set the corresponding P
x
_REG bit.
For an output, write the data to be driven out by each pin to the
corresponding bit of P
x
_REG. When a pin is configured as
standard I/O (P
x
_MODE.
y
= 0), the result of a CPU write to
P
x
_REG is immediately visible on the pin. When a pin is
configured as a special-function signal (P
x
_MODE.
y
= 1), the
associated on-chip peripheral or off-chip component controls the
pin. The CPU can still write to P
x
_REG, but the pin is unaffected
until it is switched back to its standard I/O function.
This feature allows software to configure a pin as standard I/O
(clear P
x
_MODE.
y
), initialize or overwrite the pin value, then
configure the pin as a special-function signal (set P
x
_MODE.
y
). In
this way, initialization, fault recovery, exception handling, etc., can
be done without changing the operation of the associated
peripheral.
Table 12-2. Operating Mode Control and Status Registers (Continued)
Mnemonic
Address
Description
Содержание 80C196NU
Страница 1: ...8XC196NP 80C196NU Microcontroller User s Manual...
Страница 2: ...8XC196NP 80C196NU Microcontroller User s Manual August 1995 Order Number 272479 002...
Страница 18: ...1 Guide to This Manual...
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Страница 32: ...2 Architectural Overview...
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Страница 48: ...3 Advanced Math Features...
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Страница 56: ...4 Programming Considerations...
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Страница 72: ...5 Memory Partitions...
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Страница 106: ...6 Standard and PTS Interrupts...
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Страница 144: ...7 I O Ports...
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Страница 166: ...8 Serial I O SIO Port...
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Страница 184: ...9 Pulse width Modulator...
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Страница 196: ...10 Event Processor Array EPA...
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Страница 226: ...11 Minimum Hardware Considerations...
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Страница 240: ...12 Special Operating Modes...
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Страница 256: ...13 Interfacing with External Memory...
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Страница 304: ...A Instruction Set Reference...
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Страница 374: ...B Signal Descriptions...
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Страница 390: ...C Registers...
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Страница 448: ...Glossary...
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Страница 458: ...Index...
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