Hardware Interrupt - Fujitsu MB90480 Series Hardware Manual

3.4

Hardware Interrupt

Hardware interrupt is a function to temporarily stop the execution of program being
executed by the CPU in response to an interrupt request signal from the peripheral
function. It then moves control to the interrupt processing program defined by a user.
Also, μDMAC and external interrupt may be executed as a kind of hardware interrupt.
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Hardware interrupt function
❍ Hardware interrupt function
A hardware interrupt compares the interrupt level of an interrupt request signal that is output by
the peripheral function with interrupt level mask register (ILM) in the CPU processor status (PS).
It then refers to the I-flag in the processor status (PS) to determine whether or not the interrupt
is acceptable.
If the hardware interrupt is accepted, registered contents in the CPU are automatically saved to
the system stack, and the interrupt level currently requested is stored in the interrupt level mask
register (ILM). In this event, control then branches to the corresponding interrupt vector.
❍ Multiple interrupts
Multiple hardware interrupts can start at one time.
❍ μDMAC
μDMAC is an automatic transfer function between memory and I/O, and if the transfer is
completed, a hardware interrupt starts. μDMAC does not start in a multiplex manner, and if
some μDMAC process is executed, other interrupt requests and all μDMAC requests wait
temporarily.
❍ External interrupt
An external interrupt (including wake-up interrupt) is accepted as a hardware interrupt via the
peripheral function (interrupt request detect circuit).
❍ Interrupt vector
Interrupt processing refers to the interrupt vector table assigned in memory addresses ranging
from FFFC00
For the assignment of interrupt number and interrupt vector, see Section "3.2 Interrupt Factor
and Interrupt Vector".
to FFFFFF and shared with software interrupts.
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CHAPTER 3 INTERRUPT
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