I believe you will Walter
 I just thought it prudent to mention doing some designs validation coding 
first. I do think the the through put coding could be done quickly on ARM .  If 
you're doing the other code functions on PRU you mentioned your going to face 
the learning curve anyway you asked about. So you might then try some tests 
using ADC PRU.
Otherwise I'd do the ARM part first
Usually there's always away to shoe horn something.
Regards
Mark




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  On Fri, Apr 9, 2021 at 2:00 PM, Walter Cromer<walt...@edenconceptsllc.com> 
wrote:   It's a fairly simple application really and that's what makes it 
frustrating!   We'll get there!  I learn something every day and that's just 
fine with me.
On Friday, April 9, 2021 at 2:54:55 PM UTC-4 lazarman wrote:

Plenty of data Walter thanks.
You could write some linux code that reads Data from from PRU ram( I'm not sure 
if there's several ways to get Data beyond remote messaging and reading the 
shared ram directly) factor in delay for new sample's to be updated from ADC  
at least you could ensure that works in your time frame.
If that seems OK
Then use examples for PRU I'm skeptical about needing to use assembler it's not 
the PRU read time that's a bottleneck.
I'd be interested in seeing that PRU to ARM transfer rate it should not take 
alot of time but if Linux is still interfering beyond your needed specific time 
period you will only have one choice but to find what's exactly doing this  
delay and mitigation of that will be your only hope. 
Typically a proof of concept fesigh verification like this is always wise.
If using this  chip is your only option you'd have one option left but I don't 
think you would like it.
And I'm already well known for suggestioning that option on ARM so I'm not 
going to mention it.
I do understand the value of having a feature rich OS on ARM that's royalty 
free but I've been lucky on the 50 or so projects I've worked on this wasn't 
the issue.
Another project was a Diesel engine controller they did a DVT phase first. 
Design verification Test
I wish I could help on Linux side but I can't there's plenty of people in here 
using Linux so I think you can get more ideas and help.
Not Sure how many have used Linux in actual hard realtime systems.
Your application doesn't sound extremely hard realtime so be interested in 
seeing this have a happy ending.







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  On Fri, Apr 9, 2021 at 1:16 PM, Walter Cromer<wal...@edenconceptsllc.com> 
wrote:  

Thanks Dennis.  That is in sync with my research.

On Friday, April 9, 2021 at 2:00:07 PM UTC-4 Dennis Bieber wrote:

On Fri, 9 Apr 2021 09:30:53 -0700 (PDT), in
gmane.comp.hardware.beagleboard.user Walter Cromer
<walterc-2dFtBuzUeF/tpnmuczy8b...@public.gmane.org> wrote:

>We are still experimenting but our preliminary calculations lead us to 
>believe a reading every 50 microseconds will be sufficient. We can probably 
>get by with 100 microseconds if we have to but I think the BBBw can easily 
>sample at this rate, right?

 Well, the SoC reference (SPRS717J) indicates that the ADC should be
capable of 200K samples per second. If I haven't flubbed the math, that
appears to come down to one sample every 5us.

 As I recall, the PRU runs on a 200MHz clock, and PRU instructions, for
the most, run in one clock cycle. Should be enough cycles per sample to
handle processing <G>

 Of course, it may matter how you have the ADC programmed.



-- 
Dennis L Bieber






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