8XC196MH INDUST RIAL MOT OR CONT RO L CHMO S MICRO CO NTR OLLE R
®
14
EXTINT I External Interrupt. This programmable interrupt is controlled
by the WG_PRO T ECT reg ister. This regist er cont rols
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 execut e the
EXTINT service routine. After complet ion 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 t he IDLPD
instruction that put the chip into powerdown mode.
—
INST O Instruction Fetch. This active-high output signal is valid only
during external memory bus cy cles. When high, INS T
indicates that an instruction is being fetched from exter nal
memory. The signal remains high during the entire bus cycle
of an external instruct ion fetch. INS T is low for data
accesses, including interrupt vect or fet ches and chip configu-
ration byte reads. INST is low during internal memory
fetches.
P5.1
NMI I 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 th e service routine,
execution resumes at the instruc tion 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# I On-circu it Em ulati on. Holding this pin low while the
RESET# signa l transitions from a low to a high places the
device into on-circuit emulation (ONCE) mode. ONCE mod e
isolates the device from other componen ts 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 O NCE mode, reset the device by
pulling the RESET# signal low.
P5.4
Table 7. Signal Descriptions (Continu ed)
Signal
Name Type Description Multiplexed
With