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 the 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