Interrupt
Controller
(Cont.)
Interrupt Operation (cont.)
Interrupt Edge/Level Select Register
Bit 7
Bit 6
Bit 5
Bit 4
Sense7 Sense6 Sense5 Sense4
Bit 3
Sense3
Bit 2
Sense2
PSD5XX Family
Bit 1
Bit 0
Sense1 Sense0
Bits sense 0 ... sense 7 correspond to interrupt 0 ... interrupt 7.
When these bits are set to
1 = LEVEL sensitive
0 = EDGE sensitive (positive edge)
At RESET these bits initialize as 0 i.e., all interrupts come up as Edge sensitive.
Interrupt Read Clear Register
This is a read only register. Reading this register during initialization clears all the pending
edge sensitive interrupts.
Interrupt Request Latch Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ir 7
ir 6
ir 5
ir 4
ir 3
ir 2
ir 1
ir 0
Bits ir 0...ir 7 correspond to interrupt 0 ... interrupt 7.
When any of these bits are set by the interrupt controller to a “1”, the corresponding
Interrupt is pending service.
The MCU can read the interrupt request latch which shows the status of all interrupts. The
entire interrupt request latch can be cleared by reading the Interrupt Read Clear Register,
but Level sensitive interrupts cannot be cleared.
Interrupt Priority Status Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
*
*
*
*
NOTE: * = Reserved for future use, bits set to zero.
*
vect 2 vect 1 vect 0
The value of these 3 bits (vect2, vect1 and vect0) indicates the highest priority of the
interrupt to be serviced among multiple interrupts pending. Refer to the table above for
priorities of various interrupts. Reading this register clears the highest pending interrupt.
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