80C196MH datasheet(14/41 Pages) INTEL

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8XC196MH INDUSTRIAL MOTOR CONTROL CHMOS MICROCONTROLLER

EXTINT

External Interrupt. This programmable interrupt is controlled

by the WG_PROTECT register. This register controls

whether the interrupt is edge triggered or sampled and

whether a rising edge/high level or falling edge/low level

activates the interrupt. This interrupt vectors through memory

location 203CH. If the chip is in idle mode and if EXTINT is

enabled, a valid EXTINT interrupt brings the chip back to

normal operation, where the first action is to execute the

EXTINT service routine. After completion of the service

routine, execution resumes at the instruction following the

one that put the chip into idle mode.

In powerdown mode, a valid EXTINT interrupt causes the

chip to return to normal operating mode. If EXTINT is

enabled, the EXTINT service routine is executed. Otherwise,

execution continues at the instruction following the IDLPD

instruction that put the chip into powerdown mode.

—

INST

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 configu-

ration byte reads. INST is low during internal memory

fetches.

P5.1

NMI

Nonmaskable Interrupt. In normal operating mode, a rising

edge on NMI causes a vector through the NMI interrupt at

location 203EH. NMI must be asserted for greater than one

state time to guarantee that it is recognized.

In idle mode, a rising edge on NMI brings the chip back to

normal operation, where the first action is to execute the NMI

service routine. After completion of the service routine,

execution resumes at the instruction following the one that

put the chip into idle mode.

In powerdown mode, NMI causes a return to normal

operating mode only if it is tied to EXTINT.

—

ONCE#

On-circuit Emulation. Holding this pin low while the

RESET# signal transitions from a low to a high places the

device into on-circuit emulation (ONCE) mode. ONCE mode

isolates the device from other components in the system to

allow the use of a clip-on emulator for system debugging.

This mode puts all pins except XTAL1 and XTAL2 into a high-

impedance state. To exit ONCE mode, reset the device by

pulling the RESET# signal low.

P5.4

Table 7. Signal Descriptions (Continued)

Signal

Name

Type

Description

Multiplexed

With

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