F28M35H52C: M3 Watchdog0: WatchdogHandler is triggered even before the initialization is complete

Anoja Rajalakshmi

Part Number: F28M35H52C
Other Parts Discussed in Thread: CONTROLSUITE

Hi,

I have been following the example provided in the control suite for the watchdog timer. My understanding of how the API works don't match the actual execution sequence which I would like to confirm with you.

I have attached a video of my debugging session that clearly elaborates the following.

watchdog_init()

{

// Enable the peripheral.
SysCtlPeripheralEnable(SYSCTL_PERIPH_WDOG0);

// Enable the watchdog interrupt.
IntEnable(INT_WATCHDOG);

// Unlock writes to watchdog configuration.

WatchdogUnlock(WATCHDOG0_BASE);

// Set the period of the watchdog timer.
WatchdogReloadSet(WATCHDOG0_BASE, loadValue);

// Enable reset generation from the watchdog timer.
WatchdogResetEnable(WATCHDOG0_BASE);

// Enable the watchdog timer.
WatchdogEnable(WATCHDOG0_BASE);

// Lock subsequent writes to watchdog configuration.
WatchdogLock(WATCHDOG0_BASE);

}

Problem: Even before the Watchdog LOCK function is executed, a watchdog interrupt is triggered. Can someone explain why this is happening?

Am I missing something?

Anoja

over 6 years ago

0 Ken Schachter over 6 years ago

TI__Genius 17315 points

Anoja,

Please let me know exactly which controlSUITE project you are running. Also, you might find the following F28M35 workshop materials helpful for a comparison:

https://training.ti.com/c2000-f28m35x-microcontroller-workshop?cu=1137791

I hope this helps.

- Ken

0 Anoja Rajalakshmi over 6 years ago in reply to Ken Schachter

Intellectual 290 points

Hi Ken,

I am using controlSUITE3.4.9. The folder below is where I took the watchdog example.

C:\ti\controlSUITE3.4.9\controlSUITE\device_support\f28m35x\v220\F28M35x_examples_Master\watchdog

My question still remains. Why does IntEnable(INT_WATCHDOG) result in an interrupt on WatchdogHandler? From the datasheet, what I learned is that when the WDT_LOAD Register value reaches zero, an interrupt is triggered. There is no other reason for triggering this interrupt.

Can you help me understand this?

Anoja

0 Veena Kamath over 6 years ago in reply to Anoja Rajalakshmi

TI__Mastermind 32635 points

Hi Anoja,

I tried running the example and I was unable to reproduce the issue.

Just before executing IntEnable(INT_WATCHDOG), could you check if the that interrupt line was pending (probably it was not cleared properly in the previous run)?

Regards,

Veena

0 Anoja Rajalakshmi over 6 years ago in reply to Veena Kamath

Intellectual 290 points

i Veena,

I found that after the watchdog peripheral is enabled, the WDTVALUE started incrementing. I also see that the interrupt was set already set on WDTRIS.

I tried using the normal watchdog clear, but it did not help. Can you suggest a better option?

Thanks

Anoja

0 Veena Kamath over 6 years ago in reply to Anoja Rajalakshmi

TI__Mastermind 32635 points

Hi,

While uploading videos to the forum, please check that the content is appropriate. The audio content in the video is not appropriate. Please delete the video or upload with the correct audio.

I see that the watchdog is already enabled by the time the PC reaches watchdog_init function. That is the reason why the timer is started immediately after enabling the clock. Please check why it is already enabled

Regards,

Veena

0 Anoja Rajalakshmi over 6 years ago in reply to Veena Kamath

Intellectual 290 points

The same watchdog is used in Bootloader. But just before the transfer to the application, WDT is disabled. This following code is used:

WatchdogUnlock(WATCHDOG0_BASE);
IntDisable(INT_WATCHDOG);
WatchdogIntUnregister(WATCHDOG0_BASE);
WatchdogLock(WATCHDOG0_BASE);

This did not prevent WDT interrupt from happening. I am aware that INTEN bit can be cleared only by hardware reset.

Is there a way I can avoid code from falling into handler before the initialization in application code?

0 Veena Kamath over 6 years ago in reply to Anoja Rajalakshmi

TI__Mastermind 32635 points

Hi,

The above code only disables the watchdog interrupt. Check the register field WDTCTL.INTEN. Once ser, it can be reset only by a hardware reset.

Regards,

Veena

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F28M35H52C: M3 Watchdog0: WatchdogHandler is triggered even before the initialization is complete