SIGNAL DESCRIPTIONS

 

 

Table B-3. Signal Descriptions (Continued)

Name

Type

Description

 

 

 

HOLD#

I

Bus Hold Request

 

 

An external device uses this active-low input signal to request control of the

 

 

bus. This pin functions as HOLD# only if the pin is configured for its special

 

 

function (see “Bidirectional Port Pin Configurations” on page 7-7) and the bus-

 

 

hold protocol is enabled. Setting bit 7 of the window selection register (WSR)

 

 

enables the bus-hold protocol.

 

 

HOLD# is multiplexed with P2.5.

INST

O

Instruction Fetch

 

 

This active-high output signal is valid only during external memory bus cycles.

 

 

When high, INST indicates that an instruction is being fetched from external

 

 

memory. The signal remains high during the entire bus cycle of an external

 

 

instruction fetch. INST is low for data accesses, including interrupt vector

 

 

fetches and chip configuration byte reads. INST is low during internal memory

 

 

fetches.

NMI

I

Nonmaskable Interrupt

 

 

In normal operating mode, a rising edge on NMI generates a nonmaskable

 

 

interrupt. NMI has the highest priority of all prioritized interrupts. Assert NMI for

 

 

greater than one state time to guarantee that it is recognized.

ONCE

I

On-circuit Emulation

 

 

Holding ONCE high during the rising edge of RESET# places the device into

 

 

on-circuit emulation (ONCE) mode. This mode puts all pins into a high-

 

 

impedance state, thereby isolating the device from other components in the

 

 

system. The value of ONCE is latched when the RESET# pin goes inactive.

 

 

While the device is in ONCE mode, you can debug the system using a clip-on

 

 

emulator. To exit ONCE mode, reset the device by pulling the RESET# signal

 

 

low. To prevent accidental entry into ONCE mode, connect the ONCE pin to

 

 

VSS.

P1.7:0

I/O

Port 1

 

 

This is a standard, bidirectional port that is multiplexed with individually

 

 

selectable special-function signals.

 

 

Port 1 is multiplexed as follows: P1.0/EPA0, P1.1/EPA1, P1.2/EPA2,

 

 

P1.3/EPA3, P1.4/T1CLK, P1.5/T1DIR, P1.6/T2CLK, and P1.7/T2DIR.

P2.7:0

I/O

Port 2

 

 

This is a standard bidirectional port that is multiplexed with individually

 

 

selectable special-function signals.

 

 

Port 2 is multiplexed as follows: P2.0/TXD, P2.1/RXD, P2.2/EXTINT0,

 

 

P2.3/BREQ#, P2.4/EXTINT1, P2.5/HOLD#, P2.6/HLDA#, and P2.7/CLKOUT.

P3.7:0

I/O

Port 3

 

 

This is an 8-bit, bidirectional, standard I/O port.

 

 

Port 3 is multiplexed as follows: P3.0/CS0#, P3.1/CS1#, P3.2/CS2#,

 

 

P3.3/CS3#, P3.4/CS4#, P3.5/CS5#, P3.6/EXTINT2, and P3.7/EXTINT3.

P4.3:0

I/O

Port 4

 

 

This is a 4-bit, bidirectional, standard I/O port with high-current drive capability.

 

 

Port 4 is multiplexed as follows: P4.0/PWM0, P4.1/PWM1, and P4.2/PWM2.

 

 

P4.3 is not multiplexed.

B-9

Page 383 Page 385
Page 384
Image 384
Intel 80C196NU, 8XC196NP, Microcontroller manual Hold#, Vss
Page 383 Page 385

Microcontroller, 80C196NU, 8XC196NP specifications

The Intel 8XC196NP and 80C196NU microcontrollers are part of Intel's renowned 16-bit microcontroller series that gained popularity in the 1980s and 1990s for embedded systems applications. Designed for a variety of applications, these microcontrollers are characterized by their robust performance, versatility, and industry-standard architecture.

The 8XC196NP features an enhanced instruction set with over 100 instructions, allowing for efficient code execution. It operates at clock speeds up to 16 MHz, which contributes to improved performance in time-sensitive applications. The microcontroller is equipped with a 16-bit data bus, enabling more efficient data handling compared to its 8-bit predecessors, thus accommodating complex algorithms and large data sets.

In terms of memory architecture, the 8XC196NP supports an addressable memory space of up to 64 KB of program memory and 64 KB of data memory. This configuration provides sufficient space for large applications while ensuring fast data access. The microcontroller includes integrated features such as timers, serial I/O capabilities, and interrupt processing, which enhance its functionality for real-time applications and control mechanisms.

The 80C196NU, on the other hand, is designed for lower power operation, making it suitable for battery-powered devices. This microcontroller maintains similar features to the 8XC196NP while offering advancements that support low-power consumption. The 80C196NU can also function in a range of temperature environments, making it adaptable for industrial applications.

Both the 8XC196NP and 80C196NU support external memory interfacing, allowing designers to expand the system's capability by connecting additional ROM and RAM. This flexibility makes them appealing for developing complex systems, such as motor controls, industrial automation, and consumer electronics.

Another standout feature of these microcontrollers is their built-in debugging capabilities. Intel provided hardware and software tools that enabled developers to test and troubleshoot their applications effectively, reducing the development time and increasing reliability.

Overall, the Intel 8XC196NP and 80C196NU microcontrollers stand out for their dependability, versatility, and performance, contributing significantly to the evolution of embedded system design. Their legacy continues to influence modern microcontroller technology, ensuring their relevance in a wide array of applications today.
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