AM4378: Watchdog timer

Michi Yama

Part Number: AM4378

Hi,

I would like to know watchdog timer module of AM4378.

Does AM4378 has some fail safe function for watchdog timer?

If AM4378 hung up, does not work watchdog timer also? If it is yes, is an external watchdog timer for AM4378 monitor helpful for AM4378 hung up?

And then, if AM4378 hung up, is an external reset signal to nRESET_IN_OUT pin effect to AM4378 reset?

Please advise me.

I appreciate your quick reply.

Best regards,

Michi

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

The Watchdog Timer is described in detail in section 19.5 of the AM437x TRM Rev. F. It's a free-running counter and its purpose is exactly to reset the device if the counter expires before being updated.

0 Michi Yama over 9 years ago in reply to Biser Gatchev-XID

Guru 10030 points

Dear　Biser-san,

Thank you for your quick reply.

But I don't know correct action of Watchdog timer.

I know watchdog timer is free-running. It means the watchdog timer continues its count even though AM4378 hung-up. But how about reset?

If watchdog timer is expired, is internal warm reset signal issued even though AM4378 hung-up? I wonder reset signal is issued when AM4378 hung-up.

Please advise me again.

Best regards,

Michi

0 Biser Gatchev-XID over 9 years ago in reply to Michi Yama

TI__Guru**** 393215 points

Yes, a WD reset will be issued. This is hardware and has nothing to do with the ARM core.

0 Michi Yama over 9 years ago in reply to Biser Gatchev-XID

Guru 10030 points

Dear Biser-san,

Thank you for your support.
Your quick reply is very helpful for me.

Do you have additional information for Watchdog timer?
As to your advice, I understood Watchdog timer is independence from other MPU block. But is it how?
For example, If system clock is failed, is the watchdog timer still safe?

Please advise me again.

Best regards,
Michi

0 Biser Gatchev-XID over 9 years ago in reply to Michi Yama

TI__Guru**** 393215 points

The WDT is clocked either form the 32kHz crystal oscillator or from the internal 32kHz RC oscillator. If the clock source fails the WDT will not count, naturally.

0 Michi Yama over 9 years ago in reply to Biser Gatchev-XID

Guru 10030 points

Biser-san,

Thank you for your quick reply.

If WDT uses 32kHz crystal oscillator, WDT will continue count and internal reset is issued when counter is expired?

I would like to explain to my customer how WDT is stable. Do you have any information ?

Best regards,
Michi

0 Biser Gatchev-XID over 9 years ago in reply to Michi Yama

TI__Guru**** 393215 points

Yes.

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AM4378: Watchdog timer