Watchdog LPO

martindusek — Thu, 29 Aug 2013 10:40:11 GMT

Hello,

I configured watchdog to run from LPO clock source on MK20DN512VLL10. However, I get watchdog reset everytime when the configured watchdog timeout passes, despite of refreshing the watchdog.

When I change the watchdog to run from BUS clock, it behaves as expected

Are there any precautions when running watchdog from LPO?

Re: Watchdog LPO

Hui_Ma — Tue, 03 Sep 2013 06:49:06 GMT

Hi Martin,

I am checking with this issue, I will be back when I could get any updated info.

Thank you for the patience.

B.R.

Ma Hui

Re: Watchdog LPO

Hui_Ma — Tue, 03 Sep 2013 09:00:50 GMT

Hi Martin

Thank you for the patience.

I do a test based on TWR-K60D100M board with mask set 2N22D.

I use below test code to set WDOG clock source is LPO and it works as expected.

Please check my test code below:

void test_wdog_lpo(void)

{

wdog_unlock();

/* WDOG_TOVALH: TOVALHIGH=0x0C00 */

WDOG_TOVALH = 0x0; /* Setup time-out value register high */

/* WDOG_TOVALL: TOVALLOW=2 */

WDOG_TOVALL = 0x270F; /* Setup time-out value register low */

/* WDOG_PRESC: ??=0,??=0,??=0,??=0,??=0,PRESCVAL=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0 */

WDOG_PRESC = WDOG_PRESC_PRESCVAL(0x00); /* Setup status register */

/* WDOG_STCTRLL: INTFLG=1,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=1 */

WDOG_STCTRLL = (WDOG_STCTRLL_INTFLG_MASK | 0x01U); /* Setup status register */

/* WDOG_STCTRLH: ??=0,DISTESTWDOG=1,BYTESEL=0,TESTSEL=0,TESTWDOG=0,??=0,??=1,WAITEN=1,STOPEN=1,DBGEN=0,ALLOWUPDATE=0,WINEN=0,IRQRSTEN=1,CLKSRC=1,WDOGEN=1 */

WDOG_STCTRLH = 0x1F1;

}

void wdog_unlock(void)

{

/* NOTE: DO NOT SINGLE STEP THROUGH THIS FUNCTION!!! */

/* There are timing requirements for the execution of the unlock. If

* you single step through the code you will cause the CPU to reset.

/* This sequence must execute within 20 clock cycles, so disable

* interrupts will keep the code atomic and ensure the timing.

DisableInterrupts;

/* Write 0xC520 to the unlock register */

WDOG_UNLOCK = 0xC520;

/* Followed by 0xD928 to complete the unlock */

WDOG_UNLOCK = 0xD928;

/* Re-enable interrupts now that we are done */

EnableInterrupts;

}

I use below code to refresh the WDOG:

/* Write 0xA602 to the refresh register */

WDOG_REFRESH = 0xA602;

/* Followed by 0xB480 to complete the refresh */

WDOG_REFRESH = 0xB480;

Without refresh WDOG, it will generate chip reset every 10 seconds.

Wish it helps.

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