![Intel 8XC196NT Скачать руководство пользователя страница 164](http://html1.mh-extra.com/html/intel/8xc196nt/8xc196nt_user-manual_2072210164.webp)
6-15
I/O PORTS
6.4.1
Bidirectional Ports 3 and 4 (Address/Data Bus) Operation
Figure 6-3 shows the ports 3 and 4 logic. During reset, the active-low level of RESET# turns off
Q1 and Q2 and turns on transistor Q4, which weakly holds the pin high. (Q4 can source approx-
imately –10
µΑ
at V
CC
– 1.0 volts; consult the datasheet for exact specifications.) Resistor R1 pro-
vides ESD protection for the pin.
During normal operation, the device controls the port through BUS CONTROL SELECT, an in-
ternal control signal. When the device needs to access external memory, it clears BUS CON-
TROL SELECT, selecting ADDRESS/DATA as the input to the multiplexer. ADDRESS/DATA
then drives Q1 and Q2 as complementary outputs. (Q1 can source at least –3 mA at V
CC
–0.7
volts; Q2 can sink at least 3 mA at 0.45 volts. Consult the datasheet for exact specifications.)
Table 6-11. Ports 3 and 4 Pins
Port Pins
Special-function
Signal(s)
Special-function
Signal Type
Associated Peripheral
P3.7:0
AD7:0
I/O
Address/data bus, low byte
PBUS7:0
I/O
Programming bus, low byte
SLP7:0
I/O
Slave port
P4.7:0
AD15:8
I/O
Address/data bus, high byte
PBUS15:8
I/O
Programming bus, high byte
Table 6-12. Ports 3 and 4 Control and Status Registers
Mnemonic
Address
Description
P3_PIN
P4_PIN
1FFEH
1FFFH
Port
x
Input
Each bit of P
x
_PIN reflects the current state of the corresponding pin,
regardless of the pin configuration.
P3_REG
P4_REG
1FFCH
1FFDH
Port
x
Data Output
Each bit of P
x
_REG contains data to be driven out by the corresponding
pin.
When the device requires access to external memory, it takes control of
the port and drives the address/data bit onto the pin. The address/data
bit replaces your output during this time. When the external access is
completed, the device restores your data onto the pin.
P34_DRV
1FF4H
Ports 3/4 Driver Enable Register
Bits 7 and 6 of the P34_DRV register control whether ports 3 and 4,
respectively, are configured as complementary or open-drain. Setting a
bit configures a port as complementary; clearing a bit configures a port
as open-drain. These bits affect port operation only in I/O mode.
Содержание 8XC196NT
Страница 1: ...8XC196NT Microcontroller User s Manual...
Страница 2: ...8XC196NT Microcontroller User s Manual June 1995 Order Number 272317 003...
Страница 22: ...1 Guide to This Manual...
Страница 23: ......
Страница 35: ......
Страница 36: ...2 Architectural Overview...
Страница 37: ......
Страница 49: ......
Страница 50: ...3 Programming Considerations...
Страница 51: ......
Страница 66: ...4 Memory Partitions...
Страница 67: ......
Страница 104: ...5 Standard and PTS Interrupts...
Страница 105: ......
Страница 147: ......
Страница 148: ...6 I O Ports...
Страница 149: ......
Страница 176: ...7 Serial I O SIO Port...
Страница 177: ......
Страница 194: ...8 Synchronous Serial I O SSIO Port...
Страница 195: ......
Страница 211: ......
Страница 212: ...9 Slave Port...
Страница 213: ......
Страница 231: ......
Страница 232: ...10 Event Processor Array EPA...
Страница 233: ......
Страница 270: ...11 Analog to digital Converter...
Страница 271: ......
Страница 291: ......
Страница 292: ...12 Minimum Hardware Considerations...
Страница 293: ......
Страница 306: ...13 Special Operating Modes...
Страница 307: ......
Страница 317: ......
Страница 318: ...14 Interfacing with External Memory...
Страница 319: ......
Страница 362: ...15 Programming the Nonvolatile Memory...
Страница 363: ......
Страница 408: ...A Instruction Set Reference...
Страница 409: ......
Страница 476: ...B Signal Descriptions...
Страница 477: ......
Страница 493: ......
Страница 494: ...C Registers...
Страница 495: ......
Страница 565: ......
Страница 566: ...Glossary...
Страница 567: ......
Страница 580: ...Index...
Страница 581: ......
Страница 597: ......