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Why can't I exit stop mode even if a key-on wake up interrupt was input?

Latest Updated:11/05/2008

Question:

(Timer)  I set the timer 1 count stop bit to 1 (stop counting) because I am not using timer 1. After I did that, even if a key-on wakeup interrupt is input, I cannot exit stop mode. Why is this? [2008/11/05]

Answer:

When exiting stop mode, an oscillation stabilization time is generated by timer 1. The CPU will start operating after timer 1 underflows. If timer 1 is stopped, underflow will not happen and the CPU will remain in stop mode. Set the timer 1 count stop bit to 0 (start counting) before entering stop mode. If the oscillation stabilization time set bit is 0, executing the STP (stop) instruction will automatically set 0316 to timer 1 and FF16 to prescaler 1 after the STP instruction is released. If the oscillation stabilization time set bit is 1, set values to timer 1 and prescaler 1 for the oscillation stabilization wait time appropriate for your ceramic resonator. (#107008)
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7545