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KL03Z: LPTMR after Wakeup from VLLS0

Question asked by Sara Stout-Grandy on Jun 6, 2017
Latest reply on Jun 6, 2017 by Sara Stout-Grandy



I'm trying to use the LPTMR as a time-keeper in my application. I have it running off an external clock and coming in on RTC_CLK_IN and it runs just fine. I have read chp 32 of the manual and understand that the LPTMR should be able to keep running during VLLS0 sleep mode as long as the external clock keeps running. If I understand this correctly, that should mean that I only need to initialize the LPTMR (set-up all the registers, the interrupt, etc...) and start the timer and interrupt only on the first time through the code correct? All the setting should stay after wake-up?


I'm trying to prove this and so far what I'm seeing is that the LPTMR registers do not hold their previous values after the VLLS0 wake-up (reset). I have to redo the initialization. If they don't hold their values than how can the timer keep counting during the sleep mode?


Am I doing something wrong? Is there a trick I'm missing?