Watchdog for Somanet Boards Topic is solved

Technical questions regarding the XTC tools and programming with XMOS.
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marcoandarcia
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Watchdog for Somanet Boards

Post by marcoandarcia »

Hi,

I would like to implement a watchdog timer in case my application crashes and I need to recover from the crash. I am not able to find in the documentation if this is actually possible. I found this related post and it seems the architecture doesn't have this capability. however I read that the analog support library has the feature.

If someone could clarify this for me it would be greatly appreciated.

thanks in advance.


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mon2
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Post by mon2 »

Hi. You could consider to apply an external watchdog IC like the following:

http://www.st.com/content/st_com/en/pro ... m6321.html

then program a port pin to keep this watchdog timer from expiring -> if you should have a lockup then the watchdog will perform the required LOW on #RST which is open drain. Being OD (open drain), you can apply this device's output directly onto the same #RST of the XMOS CPU.

You will want to source the ACTIVE LOW, OPEN DRAIN version of such watchdog devices.

From a quick glance, if you fail to pulse this watchdog input within 1.6 seconds, the watchdog will enforce the LOW on #RST pin. That is, do not park a static LOW or static HIGH onto the WDI pin of this device else after 1.6 seconds, the reset will trigger.
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marcoandarcia
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Post by marcoandarcia »

I was thinking about doing the same, just use an external watchdog, by any chance do you know what XMOS chips have an hardware watchdog inside? I would like to know for my next designs.

Thanks!
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mon2
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Post by mon2 »

by any chance do you know what XMOS chips have an hardware watchdog inside?
Sorry I do not at this time. Please review the XCORE-200 device datasheets for such a feature which in general are improved and more feature rich devices over the XS1 series. If the watchdog is missing internal to the CPU then slap one of these external devices.

for example from Diodes Inc. (usually are aggressive on costs) :

https://www.diodes.com/assets/Datasheet ... 4_825A.pdf

again OPEN DRAIN, ACTIVE LOW is desirable to allow for multiple similar devices to camp onto the #RST pin of the XMOS CPU.
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