MC9S08GB60A Datasheet, PDF (73/302 Pages) Freescale Semiconductor, Inc – HCS08 Microcontrollers

Chapter 5 Resets, Interrupts, and System Configuration
5.8.1 Interrupt Pin Request Status and Control Register (IRQSC)
This direct page register includes two unimplemented bits which always read 0, four read/write bits, one
read-only status bit, and one write-only bit. These bits are used to configure the IRQ function, report status,
and acknowledge IRQ events.
R
W
Reset
7
6
5
4
3
2
1
0
0
IRQF
0
IRQEDG
IRQPE
IRQIE
IRQACK
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-2. Interrupt Request Status and Control Register (IRQSC)
0
IRQMOD
0
Table 5-2. IRQSC Field Descriptions
Field
Description
5
IRQEDG
4
IRQPE
3
IRQF
2
IRQACK
1
IRQIE
0
IRQMOD
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. Also, when this bit is set, either an internal pull-up or an internal pull-down
resistor is enabled depending on the state of the IRQMOD bit.
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 a hardware
interrupt request.
0 Hardware interrupt requests from IRQF disabled (use polling).
1 Hardware interrupt requested whenever IRQF = 1.
IRQ Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. The IRQEDG control bit determines the polarity of edges and levels that are detected as interrupt
request events. See Section 5.5.2.2, “Edge and Level Sensitivity” for more details.
0 IRQ event on falling edges or rising edges only.
1 IRQ event on falling edges and low levels or on rising edges and high levels.
MC9S08GB60A Data Sheet, Rev. 2
Freescale Semiconductor
73