topic Re: Watchdog timer in K22FN in Kinetis Microcontrollers

Watchdog timer in K22FN

thiagopalmieri — Thu, 12 Jan 2017 19:03:40 GMT

Hello,

Just a simple question, how can I calculate the timer value for the watchdog in K22?

From the API, I can see that by default uses the LPO clock, which is rated as 1KHz. The timeout value from the wdog_config_t struct is uint32_t so it can hold up to 0xFFFFFFFFU, or ‭4294967295‬ cycles. The reference manual does not seem to limit the value to something lower than that.

Does that mean that the maximum possible value for the watchdog is ‭4294967 seconds?

If so, from the API documentation, the default value is 0xFFFFU, meaning a default watchdog value of 65 seconds. Is that correct?

Thanks.

Re: Watchdog timer in K22FN

Robin_Shen — Fri, 13 Jan 2017 08:07:57 GMT

Hi Thiago,

There is a 3-bit prescaler(WDOG_PRESC) for the watchdog clock source. So you need take it into account.

Best Regards,

Robin

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Re: Watchdog timer in K22FN

thiagopalmieri — Mon, 16 Jan 2017 00:47:00 GMT

Ok, so considering a prescaler of 1, putting 3000 into the timeout value, will give me a 3 second watchdog.

Thanks