mc68hc705k1 Freescale Semiconductor, Inc, mc68hc705k1 Datasheet - Page 45

• Manufacturer Part Number: mc68hc705k1
• Description: Hcmos Microcontroller Unit
• Manufacturer: Freescale Semiconductor, Inc

4.3.2.3 IRQ Status and Control Register
MC68HC705K1 — Rev. 2.0
Address:
The IRQ status and control register (ISCR) contains an external interrupt
mask, an external interrupt flag, and a flag reset bit. Unused bits read as
logic 0s.
IRQE — External Interrupt Request Enable Bit
IRQF — External Interrupt Request Flag
Reset:
Read:
Write:
This read/write bit enables external interrupts. Reset sets the IRQE
bit.
The IRQF bit is a clearable, read-only flag that is set when an external
interrupt request is pending. Reset clears the IRQF bit.
These conditions set the IRQF bit:
The CPU clears the IRQF bit when fetching the interrupt vector.
Writing to the IRQF bit has no effect. Writing a logic 1 to the IRQR bit
clears the IRQF bit.
Freescale Semiconductor, Inc.
For More Information On This Product,
1 = External interrupt processing enabled
0 = External interrupt processing disabled
1 = Interrupt request pending
0 = No interrupt request pending
a. An external interrupt signal on the IRQ/V
b. An external interrupt signal on pin PA3, PA2, PA1, or PA0
Figure 4-2. IRQ Status and Control Register (ISCR)
$000A
IRQE
Bit 7
1
when PA3–PA0 are enabled to serve as external interrupt
sources
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= Unimplemented
6
0
0
Interrupts
5
0
0
U = Unaffected
4
0
0
IRQF
3
0
2
0
0
PP
pin
IRQR
U
Interrupt Types
1
Technical Data
Interrupts
Bit 0
0
0