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Re: How would my SoC calculate an integer square root?

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upsidedown@downunder.com writes:

> On Fri, 6 Jan 2017 16:55:18 +0100, David Brown
> <david.brown@hesbynett.no> wrote:
>
>>On 06/01/17 11:50, upsidedown@downunder.com wrote:
>>> On Fri, 06 Jan 2017 08:46:11 +0100, David Brown
>>> <david.brown@hesbynett.no> wrote:
>>>
>>>> On 06/01/17 00:44, Tim Wescott wrote:
>>>>> On Thu, 05 Jan 2017 15:13:42 -0800, jladasky wrote:
>>>>>
>>>>>> On Wednesday, January 4, 2017 at 4:28:53 PM UTC-8,
>>>>>> lasselangwad...@gmail.com wrote:
>>>>>>
>>>>>>> the fpu instruction VSQRT.F32 takes 14 cycles if floats are enough that
>>>>>>> is probably hard to beat
>>>
>>> If those cycles are the same as the actual clock oscillator cycles,
>>> the 32 MHz oscillator would allow more than 2 million VSQRT
>>> instructions each second.
>>>
>>> The OP estimated a thousand square roots each second, which would
>>> consume less than  0.1 % of the clock cycles. No big deal and not a
>>> reason for optimization.
>>
>>He also made it clear that he wants to do other things during the time 
>>than just square roots, as well as wanting to minimise the time in order 
>>to reduce power consumption.
>
> He just has 99.9 % of the total CPU cycles available for the "other"
> tasks.

It looks like you did not read to the end of his sentence. It will be
consume 100% of the cycles if it only wakes up to do that one thing.

Modern MCUs can achieve very low power operation by sleeping most of the
time. Power consumption can then be nearly proportional to the wake duty
cycle. So going from "0.1%" to "0.2%" could be the difference between a
2 year and a 4 year life when powered by a coin cell say.


-- 

John Devereux

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Thread

How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-04 15:27 -0800
  Re: How would my SoC calculate an integer square root? Clifford Heath <no.spam@please.net> - 2017-01-05 10:46 +1100
    Re: How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-04 16:17 -0800
      Re: How would my SoC calculate an integer square root? lasselangwadtchristensen@gmail.com - 2017-01-04 16:28 -0800
        Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-05 09:38 +0100
        Re: How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-05 15:13 -0800
          Re: How would my SoC calculate an integer square root? Tim Wescott <seemywebsite@myfooter.really> - 2017-01-05 17:44 -0600
            Re: How would my SoC calculate an integer square root? upsidedown@downunder.com - 2017-01-06 07:54 +0200
              Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-06 09:12 +0100
                Re: How would my SoC calculate an integer square root? upsidedown@downunder.com - 2017-01-06 12:21 +0200
                Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-06 16:50 +0100
                Re: How would my SoC calculate an integer square root? upsidedown@downunder.com - 2017-01-06 19:08 +0200
                Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-08 16:49 +0100
            Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-06 08:46 +0100
              Re: How would my SoC calculate an integer square root? upsidedown@downunder.com - 2017-01-06 12:50 +0200
                Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-06 16:55 +0100
                Re: How would my SoC calculate an integer square root? upsidedown@downunder.com - 2017-01-06 19:13 +0200
                Re: How would my SoC calculate an integer square root? John Devereux <john@devereux.me.uk> - 2017-01-06 18:33 +0000
      Re: How would my SoC calculate an integer square root? Reinhardt Behm <rbehm@hushmail.com> - 2017-01-05 09:22 +0800
        Re: How would my SoC calculate an integer square root? rickman <gnuarm@gmail.com> - 2017-01-04 20:32 -0500
        Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-05 09:43 +0100
          Re: How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-05 15:38 -0800
            Re: How would my SoC calculate an integer square root? Robert Wessel <robertwessel2@yahoo.com> - 2017-01-05 19:54 -0600
            Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-06 09:25 +0100
              Re: How would my SoC calculate an integer square root? Robert Wessel <robertwessel2@yahoo.com> - 2017-01-07 23:03 -0600
                Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-08 17:04 +0100
            Re: How would my SoC calculate an integer square root? Dimiter_Popoff <dp@tgi-sci.com> - 2017-01-06 18:29 +0200
  Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-05 01:23 +0100
  Re: How would my SoC calculate an integer square root? antispam@math.uni.wroc.pl - 2017-01-05 00:54 +0000
    Re: How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-05 15:22 -0800
  Re: How would my SoC calculate an integer square root? Tim Wescott <seemywebsite@myfooter.really> - 2017-01-04 20:56 -0600
  Re: How would my SoC calculate an integer square root? Dimiter_Popoff <dp@tgi-sci.com> - 2017-01-05 12:19 +0200
  Re: How would my SoC calculate an integer square root? Tim Wescott <seemywebsite@myfooter.really> - 2017-01-06 15:40 -0600
    Re: How would my SoC calculate an integer square root? jladasky@itu.edu - 2017-01-06 16:52 -0800
      Re: How would my SoC calculate an integer square root? Wouter van Ooijen <wouter@voti.nl> - 2017-01-07 09:16 +0100
      Re: How would my SoC calculate an integer square root? Dimiter_Popoff <dp@tgi-sci.com> - 2017-01-07 12:29 +0200
        Re: How would my SoC calculate an integer square root? David Brown <david.brown@hesbynett.no> - 2017-01-08 17:09 +0100
  Re: How would my SoC calculate an integer square root? Les Cargill <lcargill99@comcast.com> - 2017-01-06 20:29 -0600
    Re: How would my SoC calculate an integer square root? Mike Perkins <spam@spam.com> - 2017-01-07 10:47 +0000
  Re: How would my SoC calculate an integer square root? Mike Perkins <spam@spam.com> - 2017-01-07 10:57 +0000

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