On 11 October 2013 04:11, Condit Alan <[email protected]> wrote:
> I am kind of like Ralph. I also have a Mesa 7i43 that I would like to be able 
> to run from a BBB. It would be great if there was a cape that could look like 
> an EPP with a driver that could run hostmot2.
>
> I have one machine that I am going to try to run from the BBB + BeBoPr + 
> Bridge. But eventually I would like to use my 7i43 with a BBB or, if Pete 
> comes up with the equivalent of a 5i25 for the BBB, sell my 7i43 and the two 
> 7i42TAs that I have.

This is quite a complicated situation, and there seems to be some
confusion about the datatypes of the various layers.

I don't think an EPP interface out of the BBB and into the 7i43 makes
much sense. The 7i43 takes commands from the EPP and produces step/dir
and/or PWM and/or GPIO signals from that.
This means that a BBB to EPP interface would probably be using the PRU
to prestend to be an EPP parallel port to tell a 7i43 to do exactly
what the PRU _already_does_ .

What would be much more interesting would be a Smart-Serial module in
the BBB PRU. Then the 7i76 could connect directly to a 25-pin D-sub on
a BBB cape, with step/dir sourced from the PRU, and the GPIO handled
by Smart-Serial.

The other alternative would be an adapter board to link PRU step/dir
or PWM to the 50-pin headers on the 7i42 cards. I am not sure if the
7i42 can work as a level-shifter, I do know that the FPGA on the Mesa
cards is 3.3V like the BBB but I am not sure which side of the ribbon
cable the level-shifting is done.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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