topic Re: K82 : WDOG in LLS3 mode in Kinetis Microcontrollers

K82 : WDOG in LLS3 mode

EugeneHiihtaja — Mon, 27 Aug 2018 12:42:18 GMT

Hello !

I keep K82 in LLS3 mode and wakeup periodically by using LPTIMER0.

For secure MCU execution flow and periodical wakeup, I also would like to use WDOG for reboot MCU if wakeup is not happens in time.

But even I configure WDOG for be used in Stop Mode :

config.clockSource = kWDOG_LpoClockSource; // 1ms
config.workMode.enableStop = true;

It is NOT reboot MCU if it stay in LLS3 mode long time without update.

Do I understand WDOG functionality in wrong way ?

Or may be I should use RTOS timer in parallel ( as back up timer ) for wakeup MCU if LPTIMER0 is suddenly freeze

while MCU in LLS3 mode ?

Please give advice !

Regards,

Eugene

Re: K82 : WDOG in LLS3 mode

kerryzhou — Tue, 28 Aug 2018 05:23:01 GMT

Hi Eugene,

Yes, you understand the WDOG in the wrong way, please check these information:

When you enter the LLS3 mode, you need to use the LLWU module to wake it.

Wish it helps you!

Have a great day,
Kerry

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Re: K82 : WDOG in LLS3 mode

EugeneHiihtaja — Tue, 28 Aug 2018 05:44:29 GMT

Hello !

Yes, yes this is a question, should I trust to one source of LLWU wakeup like LPTIMERx or second one like RTC is need to play "WDOG" role as well ?

May be external WDOG is need, MCU should wakeup from LLS3 periodically and by using GPIO pin refresh it.

It look as more reliable scheme for control MCU.

Regards,

Eugene

Re: K82 : WDOG in LLS3 mode

kerryzhou — Tue, 28 Aug 2018 06:27:06 GMT

Hi Eugene,

You can use more than one wakeup source in LLWU, please check the following information:

So, you can use both the LPTMR and RTC, or the GPIO as the LLWU wake up source.

It's OK.

More detail, please check the LLWU chapter in the chip reference manual.

Have a great day,
Kerry