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Re: Interrupts: can be lost?

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On 08/07/2020 18:31, Rick C wrote:
> On Wednesday, July 8, 2020 at 10:33:20 AM UTC-4, Tauno Voipio wrote:
>> On 8.7.20 17.01, Rick C wrote:
>>> On Wednesday, July 8, 2020 at 7:57:43 AM UTC-4, Tauno Voipio
>>> wrote:
>>>> On 8.7.20 11.43, Niklas Holsti wrote:
>>>>> On 2020-07-08 10:02, David Brown wrote:
>>>>>> On 08/07/2020 00:38, pozz wrote:
>>>>>>> https://www.safetty.net/download/pont_pttes_2001.pdf
>>>>>>> 
>>>>>>> Page 13 Note carefully what this means! There is a common
>>>>>>> misconception among the developers of embedded
>>>>>>> applications that interrupt events will never be lost.
>>>>>>> This simply is not true. If you have multiple sources of 
>>>>>>> interrupts that may appear at ‘random’ time intervals,
>>>>>>> interrupt responses can be missed: indeed, where there
>>>>>>> are several active interrupt sources, it is practically
>>>>>>> impossible to create code that will deal correctly with
>>>>>>> all possible combinations of interrupts.
>>>>>>> 
>>>>>>> Those words are incredible for me. I suspect I didn't get
>>>>>>> the point of the author. I don't think that interrupt
>>>>>>> events on modern microntrollers can be lost in some
>>>>>>> circumstances.
>>>>>> 
>>>>>> The book was written in 2001, using a microcontroller that,
>>>>>> while very popular (and still not dead), was 20 years out
>>>>>> of date at the time.  I haven't looked at it yet, and can't
>>>>>> judge the quality of the book.  But beware that some things
>>>>>> in it could be limited by that microcontroller 
>>>>>> architecture.
>>>>>> 
>>>>>> However, the principle here is correct.  It is part of a
>>>>>> more general principle that is actually quite simple:
>>>>>> 
>>>>>> If you have event counters or trackers that have limited
>>>>>> capacity, and you do not handle the events before that
>>>>>> capacity is exceeded, your system will lose events (by
>>>>>> either ignoring new ones, or ejecting old ones).
>>>>> 
>>>>> Indeed.
>>>>> 
>>>>> Note that the book's author clearly has an axe to grind
>>>>> here[1], because he advocates using "time triggering" instead
>>>>> of event- (interrupt-) triggering. So he's trying to make you
>>>>> afraid of interrupts.
>>>>> 
>>>>> Of course a similar problem applies to time-triggered
>>>>> systems: if you trigger a task every millisecond, but the
>>>>> task sometimes needs more than a millisecond to complete...
>>>>> something bad can happen.
>>>>> 
>>>>> [1] Or, as is said here in Finland, "he has his own cow in
>>>>> the ditch".
>>>> 
>>>> 
>>>> The writer is advocating the 8051 family, which is awfully
>>>> clumsy for running real multi-threading. Besides, it should be
>>>> forgotten in favor of e.g. the Cortex-M processors, which are
>>>> even at least as inexpensive as the 8051's with required
>>>> support.
>>>> 
>>>> (Mooo! from southern Finland).
>>> 
>>> That would be nice in an ideal world.  I know of one designer
>>> that will still use the 8051 processor in designs that require a
>>> second source and longevity of supply.  When qualification of a
>>> design is very expensive these properties can be very important.
>>> If the 8051 is the only processor that meets these requirements
>>> then that is the one you will use.
>>> 
>>> There are many, many ARM MCUs on the market today.  Which ones
>>> will still be around in 20 years?
>> 
>> 
>> I designed a bunch of instruments with ARM7TDMI 20 years ago, and
>> the chips are still around.
> 
> Was there any guarantee of that?  Are they second sourced if the
> original maker stops making them?  20 years ago did you know these
> chips would be around now?
> 
> All manner of devices survive the years, but how do you know which
> ones will and which ones won't?

I look at manufacturers' websites, and I ask distributors.  It's not
hard to learn what the manufacturers plan to have in their long-term
programs (to the best of their abilities, of course).  Other devices
simply continue to be produced as long as there are customers - the
68332 microcontroller, for example, has been produced for over 30 years.

> 
> The 8051 is the cockroach of MCUs.  It will survive virtually
> anything in the semiconductor industry... much to the chagrin of most
> designers.

Are you talking about the original 8051 - the Intel MCS-51 in its big
DIP package, or are you talking about the /core/ that is used in all
sorts of variations by large numbers of manufactures in different
incompatible microcontrollers?

> 
> I would love if the world would pick a half dozen MCUs in as many
> packages and designate them as the next generation 8051 to be made
> for 50 years.  It would make many project life cycles much simpler.
> 

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Thread

Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-08 00:38 +0200
  Re: Interrupts: can be lost? Clifford Heath <no.spam@please.net> - 2020-07-08 09:11 +1000
    Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-08 08:13 +0200
      Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-08 09:13 +0200
  Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-07 16:14 -0700
    Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-08 08:16 +0200
      Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 06:55 -0700
  Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-08 09:02 +0200
    Re: Interrupts: can be lost? Niklas Holsti <niklas.holsti@tidorum.invalid> - 2020-07-08 11:43 +0300
      Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-08 12:24 +0200
        Re: Interrupts: can be lost? antispam@math.uni.wroc.pl - 2020-07-09 23:24 +0000
          Re: Interrupts: can be lost? Dave Nadler <drn@nadler.com> - 2020-07-09 17:13 -0700
          Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-10 08:09 +0200
            Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 23:39 -0700
            Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-10 08:59 +0200
      Re: Interrupts: can be lost? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-07-08 14:57 +0300
        Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 07:01 -0700
          Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-08 16:07 +0200
            Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 07:35 -0700
              Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-09 14:16 +0200
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 11:04 -0700
                Re: Interrupts: can be lost? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-07-09 14:32 -0400
                Re: Interrupts: can be lost? Paul Rubin <no.email@nospam.invalid> - 2020-07-09 11:47 -0700
                Re: Interrupts: can be lost? lasselangwadtchristensen@gmail.com - 2020-07-09 15:22 -0700
                Re: Interrupts: can be lost? Dave Nadler <drn@nadler.com> - 2020-07-09 15:35 -0700
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 18:41 -0700
                Re: Interrupts: can be lost? Clifford Heath <no.spam@please.net> - 2020-07-10 16:01 +1000
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 23:28 -0700
                Re: Interrupts: can be lost? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-07-29 19:44 +0100
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 13:23 -0700
                Re: Interrupts: can be lost? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-07-29 22:57 +0100
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 16:47 -0700
                Re: Interrupts: can be lost? Clifford Heath <no.spam@please.net> - 2020-07-30 10:04 +1000
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 17:46 -0700
                Re: Interrupts: can be lost? Clifford Heath <no.spam@please.net> - 2020-07-30 11:04 +1000
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 21:16 -0700
                Re: Interrupts: can be lost? Clifford Heath <no.spam@please.net> - 2020-07-30 16:36 +1000
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-31 11:26 -0700
                Re: Interrupts: can be lost? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-07-30 01:11 +0100
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 17:53 -0700
                Re: Interrupts: can be lost? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-07-30 19:05 +0100
                Re: Interrupts: can be lost? Dimiter_Popoff <dp@tgi-sci.com> - 2020-07-31 00:21 +0300
                Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-08-04 20:40 +0200
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-04 14:36 -0700
                Re: Interrupts: can be lost? Richard Damon <Richard@Damon-Family.org> - 2020-08-04 22:32 -0400
                Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-08-05 15:26 +0200
                Re: Interrupts: can be lost? upsidedown@downunder.com - 2020-07-30 08:31 +0300
                Re: Interrupts: can be lost? Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-07-30 07:53 +0100
                Re: Interrupts: can be lost? Richard Damon <Richard@Damon-Family.org> - 2020-07-30 08:10 -0400
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 18:40 -0700
                Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-10 09:09 +0200
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-10 01:41 -0700
                Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-10 13:47 +0200
                Re: Interrupts: can be lost? Dimiter_Popoff <dp@tgi-sci.com> - 2020-07-11 13:41 +0300
          Re: Interrupts: can be lost? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-07-08 17:33 +0300
            Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 09:31 -0700
              Re: Interrupts: can be lost? David Brown <david.brown@hesbynett.no> - 2020-07-09 14:30 +0200
              Re: Interrupts: can be lost? Przemek Klosowski <przemek@tux.dot.org> - 2020-07-19 18:38 +0000
                Re: Interrupts: can be lost? Dimiter_Popoff <dp@tgi-sci.com> - 2020-07-19 23:11 +0300
                Re: Interrupts: can be lost? Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-19 13:43 -0700
    Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-08 13:19 +0200
  Re: Interrupts: can be lost? Richard Damon <Richard@Damon-Family.org> - 2020-07-09 08:00 -0400
  Re: Interrupts: can be lost? dalai lamah <antonio12358@hotmail.com> - 2020-07-11 12:12 +0200
    Re: Interrupts: can be lost? pozz <pozzugno@gmail.com> - 2020-07-13 08:35 +0200

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