Problem with Low Power Modes and Periodic Tasks (MQX 4.0)

[markdoxbeck]

I am working with MQX 4.0 and have a program that has several periodic tasks. These tasks use the

_timer_start_periodic_every() function. I need to set the program into one of the Low Power Management modes, preferably STOP mode. However, when I enter STOP mode, the timer interrupt fails to wake the system back up.

If I comment out all the periodic tasks, the system works fine. I did follow / cut / paste the MQX lowpower example included with MQX 4.0.

I made sure the LPTMR0 registers are identical in the commented and uncommented versions, just before changing over to STOP mode.

I have decreased the sleep time down from 0.5sec to 100 us.

I have doubled the main/periodictask/timertask stacks.

I am currently working on a K60 tower.

Does anyone have any suggestions on how to get this to work?

Thanks

[danielchen]

Hi Mark:

_timer_start_periodic_every relies on a systick timer, which is the default MQX tick timer.

In stop mode, Systick is not running.  It will not wake up the system from STOP modes ( STOP, VLPS, LLS,VLLSx).

In low power mode, we can use low power timer or RTC.

Regards

Daniel

Have a great day,
Daniel

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