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Per Westermark
02/24/12 05:55
Read: 373 times
Sweden


 
#186178 - Sales talk
Responding to: Kai Klaas's previous message
That white paper contained a bit too much colored sales talk.

An interesting paragraph:
"To combat non-SEU failures, a few manufacturers include a software watchdog in their digital cameras. In theory, the watchdog will restart the camera if there is a problem. However, a camera with a software watchdog canít reset itself once the camera has locked up because the watchdog is part of the digital electronics itself, which is frozen."

But few embedded developers uses just a software watchdog. Software watchdogs are mechanisms to verify that multiple threads are in working order, i.e. to supervise the software in the processor - not the processor itself.

Another interesting thing is that the white paper did not mention anything about why that external watchdog device would be any better than watchdogs in the cameras. What watchdog supervises the watchdog?

Owners of Axis cameras can quickly establish that with 24 cameras, you do not see one hung camera on average every two weeks. If it's because of built-in watchdogs or because they just don't suffer from even close to that number of hangs, I can't say. But no need for external watchdog magic.

And thinking about equipment I work with - with tenths of thousands of networked and constantly monitored units out in the field, I do not see many lockups/day. I hardly see any reboots that are not the result of software update processes etc - the devices reports back to the server why they did a reboot. If reporting a power-on, the vehicle the unit is installed in have normally been to service and had the battery disconnected.

On one hand, technology have either improved or that white paper is seriously overrating the probability of a SEU.

On another hand, released products are normally way better to take care of themselves than that white paper indicates - at least if we ignore toys.

List of 44 messages in thread
TopicAuthorDate
Pointless watchdog?      Christoph Franck      02/18/12 12:27      
   Sounds Like From What You Said...      Michael Karas      02/18/12 15:00      
      Didn't want to point fingers.      Christoph Franck      02/19/12 02:33      
         A?      JecksonS Ben      02/19/12 04:50      
            Don't forget AVR      Andy Neil      02/19/12 05:44      
               One more argument ...      Christoph Franck      02/20/12 06:14      
                  Independently testable      Per Westermark      02/20/12 11:00      
                     Slow but critical.      Christoph Franck      02/20/12 14:13      
                        Yes      Per Westermark      02/20/12 17:59      
                           ESD      Kai Klaas      02/21/12 05:38      
                               You can't      Per Westermark      02/21/12 06:04      
                                 You can...      Kai Klaas      02/21/12 06:27      
                                    But emi-filter, overvoltage protection etc may not be enough      Per Westermark      02/21/12 06:46      
                                       ESD ...      Kai Klaas      02/21/12 07:51      
                                          It's not just ESD, it's "the works"      Christoph Franck      02/21/12 08:47      
                                             I do not trust the watchdog...      Kai Klaas      02/21/12 09:44      
                                                The simpler, the more trustworthy.      Christoph Franck      02/21/12 11:08      
                                                   Less complex does not mean less probable to fail!      Kai Klaas      02/22/12 06:48      
                                                   WDT and debug breadcrumbs      Oliver Sedlacek      02/23/12 06:14      
                                                Lightning strikes      Kalpak Dabir      02/22/12 04:33      
                                                   A watchdog should never be needed - but should be there      Per Westermark      02/22/12 05:55      
                                                   A watchdog isn't a fuse...      Kai Klaas      02/22/12 07:19      
                                                      correction      Erik Malund      02/22/12 07:35      
                                                      I just can not agree with that reasoning      Per Westermark      02/22/12 08:02      
                                                         Oh please, don't...      Kai Klaas      02/22/12 17:04      
                                                            so?      Per Westermark      02/22/12 17:26      
                                                Why you need a watchdog      Oliver Sedlacek      02/23/12 04:07      
                                                   And even if you had perfect software and hardware ...      Christoph Franck      02/23/12 05:03      
                                                      Reset versus power cycle      Kai Klaas      02/23/12 05:34      
                                                         Mars Pathfinder      Christoph Franck      02/23/12 06:27      
                                                         many modern chips      Erik Malund      02/23/12 07:05      
                                                            The problem with bidirectional reset pins.      Christoph Franck      02/23/12 07:26      
                                                               The uC in question      Erik Malund      02/23/12 08:07      
                                                            Latchup      Per Westermark      02/23/12 07:29      
                                                               ONLY clocked circuits?      Erik Malund      02/23/12 08:15      
                                                                  That kitchen exhaust fan ...      Christoph Franck      02/23/12 08:42      
                                                            link...      Kai Klaas      02/24/12 05:01      
                                                               Sales talk      Per Westermark      02/24/12 05:55      
                                                   certified applications      Erik Malund      02/23/12 07:00      
                  Using external watchdog      Oliver Sedlacek      02/21/12 03:11      
                     It's a feature, actually.      Christoph Franck      02/21/12 04:16      
               Wet      JecksonS Ben      02/24/12 01:04      
   Featuritis...      Kalpak Dabir      02/20/12 19:14      
   Looking at it from another perspective      Jez Smith      02/23/12 22:38      

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