An ARM Cortex A with on-chip PRU is made only by Texas Instruments and I
don't see this gaining market share or being used in very many new
designs.  It is becoming a speciality item.  That said, I think TI will
support their customers and continue making the old chips for sometime.
But I doubt we will see PRUs in the newest and best ARM A chips.   So if
you want to continue using PRUs you will have to be content to use these TI
chips

Like me, I think many engineers are reluctant to specify a single source
part.   When the single source decides it is no longer profitable to sell
the part you are stuck.

I think the world is moving (or has moved) to using Cortex-M for this
purpose.  The "A" and "M" type ARMs have won the battle and are nearly
ubiquitous in new designs

All that said, if this is a hobby project and you only need one or two for
your own use, use what ever you like

If you ask me about future trends in motion control, what I am seeing is a
trend to move the closed control loops physically closer to the actual
motors.   Trends move glacially slow in the machine tool world it will
catch up eventually.

for example the bests stepper motors now look something like this example:
www.leadshine.com/....ntegrated-easy-servo-motors
<http://www.leadshine.com/producttypes.aspx?type=products&category=easy-servo-products&producttype=integrated-easy-servo-motors>
By moving the loop al the way out to the motor they dramatically improve
performance and reduce heat and greatly improve torque.   And don't add
much cost.  The stepper acts like a servo.

Here is another product line where the same idea is applied to serves
teknic.com/products/clearpath-brushless-dc-servo-motors/
<https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/?kw=servo%20controls&ad=156385283207&gclid=CjwKCAjwmqHPBRBQEiwAOvbR81mtRSzU3QcKx6HZO1EjGqsf-uK70HeMyhD1PYOSwS2HlKpr_46MTxoCcPoQAvD_BwE>

Basically the trend is, from a big picture point of view is keep the
encoder sensor data near the motor and never bring it back to the main
controller.      If I'm designing today I want to either emulate this or
accommodate it.  Places the PRU inside the ARM chip forces the centralized
design



On Wed, Oct 18, 2017 at 10:38 PM, Bas de Bruijn <[email protected]> wrote:

>
>
> > On 17 Oct 2017, at 23:57, Chris Albertson <[email protected]>
> wrote:
> >
> > My opinion of PRUs is that I just don't want to invest in writing PRU
> code because that chip is likely is disappear soon.  When the platform
> vanishes the code will need complete re-write.
>
> Hi Chris, how come you think that the chip:platform wil vanish soon?
>



-- 

Chris Albertson
Redondo Beach, California

-- 
website: http://www.machinekit.io blog: http://blog.machinekit.io github: 
https://github.com/machinekit
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