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7-4
8XC196NP, 80C196NU USER’S MANUAL
In special-function mode (selected by setting Px_MODE.y), SFDIR and SFDATA are input to the
multiplexers. These signals combine to drive the gates of Q1 and Q2 so that the output is high,
low, or high impedance. Special-function output signals clear SFDIR; special-function input sig-
nals set SFDIR. Table 7-5 is a logic table for special-function operation of these ports. Even if a
pin is to be used in special-function mode, you must still initialize the pin as an input or output
by writing to Px_DIR.
Resistor R1 provides ESD protection for the pin. Input signals are buffered. The ports use
Schmitt-triggered buffers for improved noise immunity. The signals are latched into the Px_PIN
sample latch and output onto the internal bus when the Px_PIN register is read.
The falling edge of RESET# turns on transistor Q3, which remains on for about 300 ns, causing
the pin to change rapidly to its reset state. The active-low level of RESET# turns on transistor Q4,
which weakly holds the pin high. (Q4 can source approximately –10
µ
A; consult the datasheet
for exact specifications.) Q4 remains on, weakly holding the pin high, until your software writes
to the Px_MODE register.
NOTE
P2.7 is an exception. After reset, P2.7 carries the CLKOUT signal rather than
being held high. When CLKOUT is selected, it is always a complementary
output.
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...
Страница 19: ......
Страница 31: ......
Страница 32: ...2 Architectural Overview...
Страница 33: ......
Страница 48: ...3 Advanced Math Features...
Страница 49: ......
Страница 56: ...4 Programming Considerations...
Страница 57: ......
Страница 72: ...5 Memory Partitions...
Страница 73: ......
Страница 106: ...6 Standard and PTS Interrupts...
Страница 107: ......
Страница 144: ...7 I O Ports...
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Страница 166: ...8 Serial I O SIO Port...
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Страница 183: ......
Страница 184: ...9 Pulse width Modulator...
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Страница 196: ...10 Event Processor Array EPA...
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Страница 225: ......
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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