topic Re: Watchdog for MC9S12A128B in S12 / MagniV Microcontrollers

Watchdog for MC9S12A128B

golf — Thu, 14 Dec 2006 17:01:51 GMT

Hi.

Is there any bit indication, which tells me wheter the Reset happened due to Watch dog(COP) or due to some other reasons?

Thanks.

Re: Watchdog for MC9S12A128B

Alban — Thu, 14 Dec 2006 18:28:03 GMT

Hello,

A different Reset vector is taken.

Up to you to execute different code or set a bit before starting the code again so you can keep trace of which vector was taken.

Cheers,
Alban.

Re: Watchdog for MC9S12A128B

golf — Thu, 14 Dec 2006 22:11:57 GMT

Is there any bit indication, which tells me wheter the Reset happened due to Watchdog(COP) without debuger?

Thanks.

Re: Watchdog for MC9S12A128B

J2MEJediMaster — Fri, 15 Dec 2006 00:15:39 GMT

There is not bit indication signaling a COP reset that I can tell. For a typical reset, the address vector xFFFE is taken. For a COP reset, the address vector xFFFA is used. As Alban explained, you'd have the COP interrupt handler code do whatever you're trying to accomplish, such as a partial recovery. The different vectors are taken both in debug mode and standalone mode.

---Tom

Re: Watchdog for MC9S12A128B

AndroTec — Wed, 10 Jan 2007 19:48:13 GMT

Hi,

I tried the "different reset vector" strategy:

My *.PRM file contains:
VECTOR 0 _Startup /* reset vector*/
VECTOR 2 _COPStartup /* COP reset vector: called when watchdog has triggered */

Via debugger I see:
00FFF8 FF FF C0 19 FF FF C0 00

0xC019 is the address of _COPStartup(), 0xC000 points to _Startup()

So far so good, but _COPStartup() is never executed. In case of a watchdog timeout, the CPU restarts with _Startup() instead of _COPStartup().

What goes wrong??

Thanks in advance!!