On Wed, 19 Apr 2017 at 04:09 [email protected] <
[email protected]> wrote:

>
> USB does not work, there is no certainty as to poll interval, there are
> repeated in depth explanations of this on the Linuxcnc forum if you are
> interested
>

Yups. Note thought that the USB module is not a USB/Parallel converter, it
contains a microcontroller that takes over the pulse generation and has
local buffering. There's a Mach3 plugin that hooks in there to offload the
work, somehow.

Probing for home/limit switches and such I could see suffering, though.


> Why do you want to use a BBB?
>

>From what I understand, LinuxCNC can use the PRU hardware on the BBB to
generate the pulse trains,which sounds like a cheap and painless way to get
timing accuracy. Aside from that, it's small and fanless.


> All you need is a small form factor ex corporate x86 desktop with a
> parport, available for £30 on ebay.
> You can run the whole machine from one parport, if you chain the limits to
> one pin
> (which limit tripped will be obvious from the table position, so you don't
> need to waste 3 pins on them)
> Or fit a £10 PCI parport card and have loads of extra IO.
>
> If I never see another beige box x86 PC, it'll be too soon :). From what I
understand, you also want a fairly dated computer, that doesn't have IMT,
turn down APM and whatnot to get decent timing accuracy. I'm no expert, and
I'm hoping not to become one.


> The downside with BBB or DE0-NANO is you still require another computer to
> access the board and provide graphics.
>

The BBB has HDMI out and a USB port. I'm pretty sure I've seen monitors &
keyboards hooked up to them with LinuxCNC/Machinekit running on them?

Looks like perhaps the Xylotex BBB_IDC26_26
<http://xylotex.netfirms.com/OSCommerce/catalog/product_info.php?products_id=117&osCsid=02d8976524cba9afc29279c2026395ad>
would
do for me, though I'd need to break the second IDC26 connector out to
something more comfortable?

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