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LPTMR interrupt not triggered when MCU is in LLS mode

Question asked by deepu n on Jan 21, 2020
Latest reply on Jan 23, 2020 by Alexis Andalon


I am new to the kinetis. I have been trying to implement a low power timer(LPTMR) with LPO as clock source. Interrupt should be triggered every 1 second.( i have a variable incrementing each time  interrupt is serviced) . The timer seems to work fine in normal mode, but when MCU goes to sleep(MCU is configured to go to sleep after 2 seconds on power up) , the power mode is set to LLS(Low Leakage Stop) where interrupt is not triggered at all.Because of which i can see that variable incremented only twice just before MCU goes to sleep(after 2 seconds on power up)

Below are my questions

1. Does LPTMR continue to run(with LPO as source), even when MCU is in LLS mode?

2.If so ,why is the interrupt not triggered in LLS mode?

3.I did see in the reference manual that wakeup interrupt need to be configured in LLS mode to wake the MCU. So will the MCU still be in LLS mode when it wakes up or will it transit from LLS to normal mode?

4.My goal is to reduce the sleep current of MCU and still have a timer running to generate delay. So, if i configure a wakeup interrupt will it affect the sleep current of my MCU.


Please feel free to correct me , if i have understood something wrong.

Thanks in advance

Deepu. N