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Bryan
Joined: 23 Apr 2005
Posts: 73
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| Timers and longevity of PIC |
 Posted: Wed May 11, 2005 4:12 pm |
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| In my project I am going to have Timer0 and Timer1 (and possibly more) running constantly (never disabled once the PIC powers up) and triggering ISR's every time they overflow. Since the project will be running 24/7 for weeks and possibly months at a time, what are the repurcussions on the PIC's life expectancy with this much timer activity at all times? I am hoping that the PIC was designed with this kind of use in mind so that it won't significantly lower the lifetime. If anyone knows, please let me know! |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Wed May 11, 2005 4:27 pm |
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I can't imagine any instance where having the timers running for that length of time would damage anything. Think about it: what's really going on is that a bunch of counters are counting. Would that affect the PIC's life? I really doubt it.
Think about how most people leave their home PCs running 24/7. Does that affect the processor's lifetime? No. It's simply a digital circuit doing what it was meant to do.
And, some personal experience: I have a device that I created over a year ago at home here, running 24/7, without any problems whatsoever. It's PIC-based, by the way, with a couple of counters active. |
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Bryan
Joined: 23 Apr 2005
Posts: 73
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| Posted: Wed May 11, 2005 4:40 pm |
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| Excellent, thanks! I was just reading the spec sheet and noticed that the internal EEPROM has a lifetime of approximately 1,000,000 cycles so I was curious if the timers had some similar sort of lifetime (Since I don't know exactly how they work internally - if there are moving parts or anything). Good to hear that you have a project that has been running for an extended period with no problems, sounds like I should have no trouble! |
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libor
Joined: 14 Dec 2004
Posts: 288
Location: Hungary
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| Posted: Thu May 12, 2005 3:05 am |
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| Quote: | | if there are moving parts or anything |
If you listen close enogh you will hear the timers ticking. 
There are similar timers / dividers implemented in silicone in any digital clock, some of them already have been working for several decades now, having made an unbelievable number of clock cycles in total. (I also tend to feel sympathy with constantly running electronics sometimes) |
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Ttelmah
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| Posted: Thu May 12, 2005 4:27 am |
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I have some of the first generation PIC processors, still running, that were built into units some 20 years ago. These all use timers, and all run 24/7.
As with all electronics, you will see the classic 'bathtub' failure curve, with a reasonable number failing early, then a long period of low failures, and then a rising failure rate (this is starting to appear now, with many of the ROM memories starting to cause problems). The earliest failures, will probably be from flash memory, on current chips.
Best Wishes |
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