[MinnowBoard] MinnowBoard Turbot Watchdog

Mike Winter (Work) mike.winter at miwin.co.uk
Tue Apr 12 09:30:47 UTC 2016


Hi Eric

How have you implemented a software Watchdog? What happens if your WD
software hangs?
 
Not that I have a lot of experience, but quite a few, if not all of the
boards that I have come across for embedded purposes have a watchdog :
Beagleboard (http://beaglebone.cameon.net/home/watchdog-timer)
RPi
(http://blog.ricardoarturocabral.com/2013/01/auto-reboot-hung-raspberry-pi-u
sing-on.html)
The PC that I am looking to replace with the Minnowboard is a DMP eBox - In
the manual, it tells you about the watchdog :
ftp://ftp.dmp.com.tw/DMP_Vortex86_Series_Software_Programming_Reference_0912
16.pdf

I just tried googling the processor used in the Turbot, and the first one
that came up was this (which includes a WD):
http://www.portwell.com/pdf/catalog/Intel_Bay_Trail_E3800.pdf

>From Wiki : "Watchdog timers are commonly found in embedded systems and
other computer-controlled equipment where humans cannot easily access the
equipment or would be unable to react to faults in a timely manner. In such
systems, the computer cannot depend on a human to reboot it if it hangs; it
must be self-reliant"

I may be wrong (frequently am!), but I think that the way these WD work, is
by software enabling the Hardware WD, which has a timer (also initiated by
s\w). The timer starts to count down, and if it gets to 0, will perform a
hardware reset - same as physically turning the power off & then on again.
The software's 'job' is to make sure the timer never gets to 0, so should
frequently set the timer back to your specified WD interval.

What I normally do is set the WD timeout period to 3 seconds, and then in my
s\w initialize the WD every second. This allows you to miss a cycle by
accident, without the PC rebooting.

Regards

Mike



-----Original Message-----
From: Eric [mailto:ericolv at cox.net] 
Sent: 08 April 2016 20:39
To: 'MinnowBoard Development and Community Discussion'
<elinux-minnowboard at lists.elinux.org>
Subject: Re: [MinnowBoard] MinnowBoard Turbot Watchdog

I've not heard of any PC motherboard or embedded board with a feature like
this.   However, I have implemented this type of functionality in software.

-----Original Message-----
From: elinux-MinnowBoard
[mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of Mike
Winter (Work)
Sent: Friday, April 8, 2016 7:02 AM
To: 'MinnowBoard Development and Community Discussion'
Subject: Re: [MinnowBoard] MinnowBoard Turbot Watchdog

Hi John, thanks for the reply.

I am looking at using the Minnowboard in an embedded environment. Other PCs
that I have used have a hardware Watchdog, which, when turned on, you are
required to poll at definable intervals. If you do not poll it quickly
enough (or stop polling, due to hung software), the PC will perform a hard
reset. Is this a feature of the Minnowboard, or likely to be incorporated in
future versions?

Thanks again for your help

Mike

-----Original Message-----
From: John Hawley [mailto:john.hawley at intel.com]
Sent: 08 April 2016 06:09
To: elinux-minnowboard at lists.elinux.org
Subject: Re: [MinnowBoard] MinnowBoard Turbot Watchdog

What kind of watchdog are you looking for / need?  Just trying to figure out
what kind of watchdog you are looking for.

- John 'Warthog9' Hawley

On 4/7/2016 3:25 AM, Mike Winter (Work) wrote:
> I have a MinnowBoard Turbot on the way, but when I ordered I forgot to 
> check whether there is a watchdog, which is a requirement for my 
> project. Is there one in the Turbot, I haven't found any mention of one?
> 
>  
> 
> Regards
> 
> *Mike Winter*
> 
>  
> 
> 
> 
> _______________________________________________
> elinux-MinnowBoard mailing list
> elinux-MinnowBoard at lists.elinux.org
> http://lists.elinux.org/mailman/listinfo/elinux-minnowboard
> 
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