Re: GA144 Programming

From	rickman <gnuarm@gmail.com>
Newsgroups	comp.lang.forth
Subject	Re: GA144 Programming
Date	2012-07-16 11:17 -0700
Organization	http://groups.google.com
Message-ID	<9cffb93a-9c6c-4d1d-80b1-a7d52bae573e@googlegroups.com> (permalink)
References	<1121f776-65ff-4d4a-9246-f8e3d50e0318@googlegroups.com> <a6j3o8FiubU1@mid.individual.net>

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On Monday, July 16, 2012 2:09:50 PM UTC-4, Paul E. Bennett wrote:
> rickman wrote:
> 
> &gt; I have reached the point where I need to start figuring out code timing
> &gt; for an application I am considering and I wanted to bounce some ideas off
> &gt; of people.  But I not sure I have enough information from the
> &gt; documentation to use the ADC.  There is a brief description in DB001 -
> &gt; F18A, section 3 I/O Facilities.  But the description is a bit vague.
> &gt; 
> I have been exploring the ADC transfer curve and have managed to get a 
> fairly close polynomial for it worked out. Next step would be to try some 
> coding (next bit of spare time).

What data did you use for the actual curve?  The problem is that the curve is not static, but a function of PVT (Process, Voltage and Temperature).  Will you be able to adjust for that?  

To be honest, this the one of the last things I plan to deal with given the higher sample rates I'll be working with.  At 40 MSPS there are less than 6 bits of significance.  I bet the non-linearity in the sweet spot range of around 1 Vpp is not much more than 1 lsb.  Of course at slower rates and higher resolutions linearity will need to be corrected.  

If you want to code this efficiently, I recommend that you study Chuck's current "blog" site postings.  There are getting to be lots of examples of how to efficiently program the GA144.  

Rick

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GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-15 13:29 -0700
  Re: GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-15 14:31 -0700
  Re: GA144 Programming Clyde Phillips <cwpjr02@gmail.com> - 2012-07-15 21:43 -0700
    Re: GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-16 07:52 -0700
    Re: GA144 Programming "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2012-07-16 17:47 -0700
  Re: GA144 Programming "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2012-07-16 19:09 +0100
    Re: GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-16 11:17 -0700
      Re: GA144 Programming "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2012-07-16 19:43 +0100
  Re: GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-25 15:10 -0700
    Re: GA144 Programming Paul Rubin <no.email@nospam.invalid> - 2012-07-25 16:23 -0700
      Re: GA144 Programming rickman <gnuarm@gmail.com> - 2012-07-27 21:49 -0700

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