MC9S08JM16 Datasheet, PDF (69/386 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 5 Resets, Interrupts, and System Configuration
Table 5-2. IRQSC Register Field Descriptions
Field
Description
6
IRQPDD
5
IRQEDG
4
IRQPE
3
IRQF
2
IRQACK
1
IRQIE
0
IRQMOD
Interrupt Request (IRQ) Pull Device Disable — This read/write control bit is used to disable the internal pullup
device when the IRQ pin is enabled (IRQPE = 1) allowing for an external device to be used.
0 IRQ pull device enabled if IRQPE = 1.
1 IRQ pull device disabled if IRQPE = 1.
Interrupt Request (IRQ) Edge Select — This read/write control bit is used to select the polarity of edges or
levels on the IRQ pin that cause IRQF to be set. The IRQMOD control bit determines whether the IRQ pin is
sensitive to both edges and levels or only edges. When the IRQ pin is enabled as the IRQ input and is configured
to detect rising edges, the optional pullup resistor is re-configured as an optional pulldown resistor.
0 IRQ is falling edge or falling edge/low-level sensitive.
1 IRQ is rising edge or rising edge/high-level sensitive.
IRQ Pin Enable — This read/write control bit enables the IRQ pin function. When this bit is set, the IRQ pin can
be used as an interrupt request.
0 IRQ pin function is disabled.
1 IRQ pin function is enabled.
IRQ Flag — This read-only status bit indicates when an interrupt request event has occurred.
0 No IRQ request.
1 IRQ event detected.
IRQ Acknowledge — This write-only bit is used to acknowledge interrupt request events (write 1 to clear IRQF).
Writing 0 has no meaning or effect. Reads always return 0. If edge-and-level detection is selected (IRQMOD = 1),
IRQF cannot be cleared while the IRQ pin remains at its asserted level.
IRQ Interrupt Enable — This read/write control bit determines whether IRQ events generate an interrupt
request.
0 Interrupt request when IRQF set is disabled (use polling).
1 Interrupt requested whenever IRQF = 1.
IRQ Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. See Section 5.5.2.2, “Edge and Level Sensitivity,” for more details.
0 IRQ event on falling/rising edges only.
1 IRQ event on falling/rising edges and low/high levels.
5.7.2 System Reset Status Register (SRS)
This register includes seven read-only status flags to indicate the source of the most recent reset. When a
debug host forces reset by writing 1 to BDFR in the SBDFR register, none of the status bits in SRS will
be set. Writing any value to this register address clears the COP watchdog timer without affecting the
contents of this register. The reset state of these bits depends on what caused the MCU to reset.
MC9S08JM16 Series Data Sheet, Rev. 2
Freescale Semiconductor
69