cp3ub17 National Semiconductor Corporation, cp3ub17 Datasheet - Page 50

• Manufacturer Part Number: cp3ub17
• Description: Reprogrammable Connectivity Processor With Usb Interface
• Manufacturer: National Semiconductor Corporation

All reserved or unused interrupt vectors should point to a
default or error interrupt handlers.
10.5
NESTED INTERRUPTS
Nested NMI interrupts are always enabled. Nested
maskable interrupts are disabled by default, however an in-
terrupt handler can allow nested maskable interrupts by set-
ting the I bit in the PSR. The LPR instruction is used to set
the I bit.
Nesting of specific maskable interrupts can be allowed by
disabling interrupts from sources for which nesting is not al-
lowed, before setting the I bit. Individual maskable interrupt
sources can be disabled using the IENAM0 and IENAM1
registers.
Any number of levels of nested interrupts are allowed, limit-
ed only by the available memory for the interrupt stack.
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