MC68HC705J1ACPE Datasheet, PDF (105/162 Pages) Freescale Semiconductor, Inc – Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.
External Interrupt Module (IRQ)
Operation
If edge- and level-sensitive triggering is selected, a rising edge or a high
level on a PA0–PA3 pin latches an external interrupt request. Edge- and
level-sensitive triggering allows the use of multiple wired-OR external
interrupt sources. As long as any source is holding a PA0–PA3 pin high,
an external interrupt request is latched, and the CPU continues to
execute the interrupt service routine.
If edge-sensitive only triggering is selected, a rising edge on a PA0–PA3
pin latches an external interrupt request. A subsequent external interrupt
request can be latched only after the voltage level of the previous
interrupt signal returns to logic 0 and then rises again to logic 1.
NOTE:
The branch if interrupt pin is high (BIH) and branch if interrupt pin is low
(BIL) instructions apply only to the level on the IRQ/V_PP pin itself and not
to the output of the logic OR function with the PA0–PA3 pins. The state
of the individual port A pins can be checked by reading the appropriate
port A pins as inputs.
Enabled PA0–PA3 pins cause an IRQ interrupt regardless of whether
these pins are configured as inputs or outputs.
The IRQ pin has an internal Schmitt trigger. The optional external
interrupts (PA0–PA3) do not have internal Schmitt triggers.
The interrupt mask bit (I) in the condition code register (CCR) disables
all maskable interrupt requests, including external interrupt requests.
MC68HC705J1A — Rev. 4.0
External Interrupt Module (IRQ)
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Technical Data