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Does an SFR break occurs after the stop mode entered by the 72k4 STBC?

Latest Updated:12/01/2011

Question:

An SFR illegal break occurs after the STOP mode is entered by execution of the 78K4 standby command (STBC) upon recovery from the standby status.

Answer:

There seems to be a problem with the STOP release method.
STOP mode can be released either by generating a vectored interrupt (the CPU is in the interrupt-enabled status) or without generating a vectored interrupt (the CPU is in the interrupt-disabled status).
Judging from the contents of your inquiry, you are employing the vectored interrupt generation release method.
Since the vector in this case has an area of only a 16-bit address, if 3 bytes are required for the interrupt jump destination, direct branching from the vector is not possible (a program loop occurs and the subsequent operation is unpredictable).

When the interrupt servicing routine is in an area indexed within 2 bytes, the interrupt servicing routine can be correctly branched to, so processing is possible as long as the interrupt servicing routine is correct.
Suitable Products
RL78 Family
78K Family
UPD784xxx