> On Mar 29, 2018, at 00:37 , Bas de Bruijn <[email protected]> wrote:
>
>
>> On 28 Mar 2018, at 22:02, Rick Mann <[email protected]> wrote:
>>
>> I'm just starting on building a CNC router using MachineKit and a BBB.
>> You'll still need a board of some kind, if for no other reason than to
>> isolate the BBB from the rest of your system. I bought an OPTOCAPE ($165) to
>> experiment with, but I will be designing and building my own board at the
>> same time (mostly because I want all the right connectors on it).
>>
>> So far, I have not had any success figuring out how to get MachineKit up and
>> running. I also haven't tried that hard, but it's really non-obvious, and
>> there are huge gaps in the documentation. I finally have enough pieces in
>> place to try this in earnest, but my shop office buildout has taken priority
>> (can't make room for the router until I finish that).
>
> Hi Rick,
>
> Can you give an example where you find documentation lacking?
> here’s a link on how to set up Machinekit.
> http://www.machinekit.io/docs/getting-started/getting-started-platform/
So, here's just a small bit of how the documentation is lacking.
- There's no 30,000' view of how MachineKit is structured and runs. I'm vaguely
aware via osmosis that there are some layers, and possibility for remote UI.
- The Getting Started/Setting up machinekit on a platform really just tells you
how to get the software installed. Perfectly fine place to start, but then says
nothing more.
- So, I try the next line in the list of Getting Started links: System
Requirements. Well, that doesn't really help, and in fact adds confusion, since
I'm doing this on a Beaglebone Black, which doesn't meet the minimum
requirements. So I ignore that knowing people are successful with BBB.
- Next is Stepper Quickstart, which "assumes you have done a standard install
from the Live CD," but the previous instructions make no mention of a Live CD.
Okay, ignore that, it's clearly out of date.
- Latency Test. I can probably ignore this because I'm on BBB.
- Sherline & Xylotex. What? Okay, I know a Sherline is a brand of small
mill/lathe. I google Xylotex to see what that is. Some kind of DIY CNC? Neither
of these seems important to my setup, and certainly don't merit the same level
in the outline of Stepper Quickstart as Latency Test or Machine Information.
- Machine Information. Okay, this looks like something to pay attention to.
But wow, is this sparse, and does it presume a lot of MachineKit-specific
knowledge. Good thing I know a fair bit about what it would take to implement
this stuff from scratch, so I can infer some of this, but I feel already like
some basic introductory material has been skipped.
(Note: these tables look like screen shots from a UI I have yet to
experience. This is the 10th time I've looked at this page, and only now do I
realize it's just a table showing the info I'm intended to gather. I think)
- Pinout Information: Talks about parallel port. Well, that's clearly not
applicable.
- Mechanical Information: Okay, I don't really care about this stuff right
now, I'm literally just trying to get one ClearPath stepper to work with my BBB
setup as a proof of concept. Back to Getting Started list.
- Stepper Configuration Wizard: Better introductory information than anything
else so far, but says it's for "standard parallel port." Does that mean I can't
use it on BBB? Not sure. But I still don't know how to even get to this. Maybe
the item "Running MachineKit" I saw further down the list is helpful. Not sure
why it wasn't the first thing after installation.
- Mesa Configuration Wizard: Okay, I own a Tormach, so I know what "Mesa"
probably means, I'm gonna skip this one.
- Running Machinekit: Hey! Figured out how to run mk. Okay, I see there is a
pru_examples option in the configuration UI that pops up. There's no
information displayed with it, but let's choose it. It offers to copy it to my
home dir, then restarts machinekit. I see a splash screen, then it all ends
with some errors.
I'll write another post about those errors, but that's my initial feedback on
the state of the docs. I hope it helps.
>
>>
>> I'm fairly sure MachineKit and BBB is the right way to go. MachineKit seems
>> to want a real-time Linux kernel even though I don't think it's necessary
>> because of the PRUs. There's also this project which might be worth
>> considering:
>
> The PRU’s only do step generation. You basically want to have an RT kernel
> because you want to update the commanded position and read out the current
> position in a timely manner. RT preempt kernels are common enough not to have
> them build yourself. The Beagleboard has RT kernels.
>
>> <https://github.com/hzeller/beagleg>.
>>
>>> On Mar 28, 2018, at 09:50 , Andrew Voelkel <[email protected]>
>>> wrote:
>>>
>>> Hi,
>>>
>>> I was referred to the MachineKit group after discussing plans to switch my
>>> router machine control from Mach3 on Windoze. He told me that people are
>>> using the PRU on the BBB to do the stepper motor control for LinuxCNC. That
>>> sounded attractive.
>>>
>>> (I have a Gecko motor driver. My system is 4 motors, but only because the x
>>> motor is mirrored.)
>>>
>>> So I did a forum search here and it didn't really clear things up that
>>> much. It was pretty down in the weeds.
>>>
>>> What I'm trying to figure out is whether using MachineKit LinuxCNC and the
>>> BBB with the PRU is standard fare or not. I have basically two choices as
>>> far as I can tell:
>>> • Use MachineKit and a BBB I have lying around, and the PRU as stepper
>>> control. Ride off into the sunset.
>>> • Use a Mesa 7i92 for stepper motor control and standard LinuxCNC
>>> instead of MachineKit, making sure that I have a realtime kernel installed
>>> one way or the other. I'd probably still use the BBB as my CPU.
>>> Although I like the idea #1 above because it is a one board solution (and I
>>> save $89), the most important thing is that I choose the system that is
>>> easiest to set up and most reliable.
>>>
>>> Does anyone have any opinions of which that might be? If both of these
>>> configurations are regularly used, then I'll go with BBB and PRU and
>>> MachineKit, since I can try it all out for the cost of my own time. But I
>>> value my time so I don't want to get too experimental.
>>>
>>> Thanks for any help!!
>>>
>>> --
>>> website: http://www.machinekit.io blog: http://blog.machinekit.io github:
>>> https://github.com/machinekit
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>>
>>
>> --
>> Rick Mann
>> [email protected]
>>
>>
>> --
>> website: http://www.machinekit.io blog: http://blog.machinekit.io github:
>> https://github.com/machinekit
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>
> --
> website: http://www.machinekit.io blog: http://blog.machinekit.io github:
> https://github.com/machinekit
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--
Rick Mann
[email protected]
--
website: http://www.machinekit.io blog: http://blog.machinekit.io github:
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