FRDM-KL03: Waking from LLWU vs LPTMR Interrupt, why is the current not the same?

[sarastout-grand]

Hello,

I'm working with the FRDM-KL03 and KDS. I can successfully wake from VLLS0 with either the LLWU pin interrupt or the LPTMR interrupt. However, the resulting current measurements are not the same.

When the processor wakes via the LPTMR interrupt, the wake-up current is the same as the current before going to sleep (~5.6mA). When the processor wakes via the LLWU pin interrup, the wake-up current is not the same as the going to sleep current, it is about 1mA less (~4.5mA).

I'm at a loss to explain this. Is it not returning to the same state? Is it enabling something in the background that I'm not aware of? Any ideas?

Thanks,

Sara

[sarastout-grand · Accepted solution]

Hi Kerry,

Nevermind, I figured out the problem! I had the wrong bit set in the LLWU ISR to clear the flag.

Works fine now. Thanks for your help!

Sara

[kerryzhou]

Hi Sara Stout-Grandy,

    Thank you for your root problem sharing.

Have a great day,
Kerry

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[kerryzhou]

Hi Sara Stout-Grandy,

    What the clock source of your LPTMR?

    You must make use the clock source of your LPTMR is working in VLLS0. And your VLLS0 is really entered.

    Besides, whether the clock mode is the same as the PIN interrupt before enter VLLS0?

    You can send me your test project, I will check it on my FRDM-KL03 board.

    The KSDK sample code for KL03 low power, when enter VLLS0, the LPTMR is not working, just can wake up by the wakeup pin.

Have a great day,
Kerry

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[sarastout-grand]

Hi Kerry,

I am running the LPTMR with an external clock coming in on the RTC_CLK_IN line (4kHz). When I wake up using the LPTMR, the external clock is still running. When I go to sleep and wake up with the LLWU, the external clock is not running. With no external clock running, directly after I reset, I read ~5.6mA. I push SW2 to go to VLLS0. I see the current drop to 0.24uA. When I push SW3 (LLWU_P4), the chip wakes up and I read ~4.5mA. The external clock is off for all these cases. It is also interesting to note that I can’t go back to VLSS0 from the state showing ~4.5mA, whereas I can from the LPTMR wake-up which comes back to the original current of 5.6mA.

I have attached my code for you run and verify what I'm seeing. Let me know what you find!

Thanks,

Sara

Sara Stout-Grandy, M.Eng., Ph.D., P.Eng.

Senior Hardware Designer

20 Angus Morton Dr., Bedford,

NS, Canada, B4B 0L9

902-450-1700, x278