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How to perform interrupt processing (maskable)?

Latest Updated:03/20/2017

Question:

I want to perform interrupt processing (maskable) but control does not branch to the interrupt program.
Although the EI instruction is executed, NP = 1 and ID = 1.

Answer:

A possibility for why NP = 1 may be one of the following:
- An NMI has been acknowledged.
- The PSW has been rewritten by the LDSR instruction.
- The value set in EIPSW when returning from a maskable interrupt is incorrect.

Does control branch to the initialization processing during the interrupt (NMI) service, resulting in re-initialization?
During interrupt servicing, the status is recorded to flags (NP bit or ISPR.ISPRn bit), and this status is retained until a RETI instruction is executed.
Interrupts cannot be acknowledged as long as these flags hold the status.
Suitable Products
V850 Family