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Why is the level of past interrupt is held so no other interrupts occur?

Latest Updated:03/27/2017


One way to jump from within an interrupt to the start of a program (for initialization) is to set dummy values to the EIPC and EIPSW registers and use a RETI instruction to jump.
Sometimes, the level of the previous interrupt is held so that no other interrupts can occur.


Perhaps this is because of multiple interrupts.

If so, executing one RETI instruction will clear only the bit in the ISPR register that corresponds to the highest-priority interrupt.

To handle multiple interrupts in this case, an RETI instruction must be executed repeatedly until the ISPR register value becomes 00 (all the bits cleared).


Also refer to the following FAQ item:

Initialization with watchdog timer interrupts [V850/SA, V850/SB]

Suitable Products
V850 Family