topic Re: K64F watchdog timeout value in Kinetis Microcontrollers

K64F watchdog timeout value

unknowncoder — Tue, 06 Feb 2018 22:46:02 GMT

I am having trouble converting millisecond to the watchdog timeout value when using MCUXpresso watchdog driver.

Please validate my math.

One tick of the watchdog = 1 ms. With the given configuration

Watchdog clock = kWDOG_LpoClockSource = 1KHz
Watchdog prescaler = 1

Therefore when I setup the watchdog I do

wdog_config_t config;

WDOG_GetDefaultConfig(&config);

config.timeoutValue = 1000;

This should make the watchdog timeout in 1 second but it seem to be timing out alot sooner.

Re: K64F watchdog timeout value

jschepler — Thu, 08 Feb 2018 21:11:08 GMT

Hi Desmond,

Can you show your entire config structure?

If you actually are assigning "1" to you're prescaler value in the config then it will be divided by 2 in the driver.

I am using KSDK 1.3.0 and the ENUM to divide by 1 in the driver is: kWdogClkPrescalerDivide1

The enum value of that is 0.

Re: K64F watchdog timeout value

Robin_Shen — Sun, 11 Feb 2018 07:51:52 GMT

Hi Desmond,

Would you please tell us how did you see it time out alot sooner?
Maybe you can toggle a pin and then WDOG_Refresh it only once. Measure the Reset_b pin waveform and observe if the voltage will low after 1ms.

Best Regards,

Robin

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Re: K64F watchdog timeout value

unknowncoder — Sun, 11 Feb 2018 16:07:19 GMT

This problem has been resolved.

There some some incorrect timer calculation occurring in the code.