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(M16C Family products other than the M32C/80 Series, and the M16C/80 Seires) Priority level is "0" + Request bit is "1": Priority level to "7"?

Latest Updated:02/14/2006

Question:

When the interrupt priority level is "0" and interrupt request bit is "1", what would happen if I set the interrupt priority level to "7"? Will the interrupt be accepted, or will the interrupt request bit be cleared to "0"? [M16C/62P Group, M16C/62N (incl. M3062GF8NFP/GP) Group, M16C/62A (incl. M16C/62T), M16C/62M Group, M16C/30 Series, M16C/Tiny Seires, M16C/10 Series]

[About the M32C/80 Series, and the M16C/80 Series products, click here.]

Answer:

The interrupt will be accepted. Then, the interrupt request bit will be cleared.
However, if you use the MOV instruction to change the interrupt priority level, the interrupt request bit may be cleared to "0". The interrupt will not be accepted when the interrupt request bit is cleared at this time. To avoid this problem, please use the following instructions to change the interrupt priority level:

AND, OR, BCLR, BSET

In addition, make sure you modify the interrupt control register at a location where the interrupt request for that register will not occur. If there is possibility of an interrupt request being generated, disable the interrupt before making any modifications. Please refer to the manual for more details.

Suitable Products
M16C/62A
M16C/62A(M16C/62T)
M16C/62M
M16C/62N
M16C/62N(M3062GF8NFP, M3062GF8NGP)
M16C/62P
M16C/63
M16C/64
M16C/64A
M16C/64C
M16C/65
M16C/65C
M16C/6C
M16C/6N4, M16C/6N5
M16C/6NK, M16C/6NL, M16C/6NM, M16C/6NN
M16C/5L, M16C/56
M16C/5LD, M16C/56D
M16C/5M, M16C/57
M16C/30P
M16C/29
M16C/28
M16C/26A
M16C/1N