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(4508, 4509, 4571) Why do interrupts need to be disabled before execution of the EPOF?

Latest Updated:07/04/2003

Question:

(Power Save)  Why do interrupts need to be disabled before execution of the EPOF instruction?

Answer:

The EPOF instruction and the POF instruction must be executed in succession in order to switch to RAM back-up mode. If an interrupt occurs between these two instructions, the MCU will not go into RAM back-up mode even after returning from the interrupt routine. For this reason, disable interrupts by executing the DI instruction before executing the EPOF instruction. (#105022)
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