help for a newbie please

[Roberto Gonzalez]

Hi all.
Recently I have finally manufactured my CNC milling machine and I have proposed to handle it with a BBB and Machinekit which I already have (without any type of cape). After much reading and reading, I am still completely lost and I write here with the hope of receiving help, as I have seen that you have a lot of knowledge about it. I give you all my data and expectations to see if you can help me.

At the moment it is a three-axis milling machine with Nema23 motors and external drivers and in the future I would like to extend it to 5 axes and possibly to Nema34. On the other hand, I have a Chinese parallel port breakout board. I have managed to flash the BBB as well as run Machinekit following tutorials. And here all my doubts begin.

Is it strictly necessary that I buy a cape to be able to operate the machine or would it be worth the breakout board that I already have and connect it pin to pin to the corresponding ones of the BBB? Should you need one which would be the easiest to acquire and configure? I tried to write an email for a BeBop ++ but it seems that the address does not exist.

And on the other hand and already to finish, so I have read (and tried) once created and modified one of the configurations that well within the Machinekit itself I must compile it or run some kind of program to make it functional and activate the pins of the headers of the BBB, right? I have tried and executed some but I do not know how to check if I have done well 😔.

I would appreciate any help, references, links to follow, etc. It is very hard to be self-taught. Thank you very much in advance even if only for the inconvenience and the time spent reading.

Thank you!!

[Jeff Pollard]

Hi,

  The BBB outputs 3.3V for its digital I/O.  This may, or may not be enough to drive your motor drives.  You do not *have* to have a cape if you wired the BBB pins to the parallel port BOB and from there to your motor drive.

  Different version of the MachineKit software act differently on start up.  I'm more familiar with the older (2017) software.  Most of the pre-configured INI and HAL files from back then will work without modifications.  New version may require changes to pin setup files for device tree overlay.

  If you start with an older Machinekit, I'd recommend using the CRAMPS configuration, as not only does it work, but there are also schematics available of the CRAMPS board you can reference to when you are making the connections from the BBB to your BOB.

https://reprap.org/wiki/CRAMPS#Schematic_Files

Jeff

[Roberto Gonzalez]

Hello Jeff, thanks for the quick response.

So far I have done tests with a mega Arduino and the engines are going well so I understand that there would be no problem. From what I have read so far here CRAMPS was an option that I contemplated but I had doubts if it would serve me for the Nema 23 and expand to 5 axes. Would you recommend buying the cape and forgetting about the BOB? As for the configuration would be to adapt the file .INI and .HAL to my needs and execute the file setup.sh? what I've already tried it and the only thing I see is a line in the terminal or a Splash of this if it was executed under a graphic environment and as an ignorant newbie I do not know if it should happen and it is good or bad

[Jeff Pollard]

Hi,

  The CRAMPS has space for built-in drivers, and it not itself a breakout board, so really would not be useful for your system as a hardware option.  The reason I mention it is that it is a complete software setup that would be ready to run and has schematic available to see how the INI and HAL files are used with direct relation to the BBB hardware.

  The CRAMPS wiring configuration is not tied to any size stepper motor (the board would be though).  The CRAMPS configuration can handle up to 6 motors.

  The easiest way to start using the BBB and MachineKit would be with the BBB in full "desktop" mode, using a USB keyboard, mouse and an HDMI monitor.  This way you don't have to worry about trying to run through a terminal (if you meant SSH in on a remote terminal).  You can use the Machinekit software running the Axis GUI to try and control your motors.  Start with the CRAMPS configuration and its pinout.  Use BBB pins for STEP/DIR that are specified by the CRAMPS ini and hal.  This way you do not need to worry about changing the setup.sh.  I would recommend one of the older versions of Machinekit software from a couple years back as they would run "out of the box" on a BBB.  The newer ones may require some tweaking.

  From the main linux desktop screen, open a linux terminal and type Machinekit followed by a carriage return.

  A selector screen should come up and allow you to select the CRAMPS setup.  Do that, and after it has initialized, it will bring up the Axis GUI.

  From there you can start making your connections from the BBB pins to your motor driver.  Start with only one drive and get it working before trying to add more i.e. the CRAMPS specified X STEP, X DIR and a GND pin are all you would need to use to go from the BBB to your drive (make sure your drive does not need an external enable signals to be ready to go).  Then try to jog the X axis.  Depending on the CRAMPS configuration (which I'm only vaguely familiar with) you may need to have a jumper wire between two BBB pins: an enable output and an enable input.  You can read the HAL file to figure out which pins to jumper.  I don't know if there is a setup manual for CRAMPS that describes setup of not, but without the jumper you would either have to change the HAL (not recommended to start with) or simply add the jumper.  Once you get familiar with getting the X moving, you can move on to adding more axes, or start modifying the INI and HAL as necessary.  Don't start modifying any of the files until you actually have something working/moving.

Jeff

[Roberto Gonzalez]

Thanks again, Jeff.

That was basically my idea, in fact I have already launched an axis GUI with the CRAMPS configuration, all I would have to do would be to adjust a few parameters in the .INI to adapt them to my engines, I have printed the scheme you mentioned (thank you very much) and in the next few days I will test the wiring.

Now my question is, once the setup is chosen, running the setup.sh file is all I have to do to make it operational? surely it is a stupid doubt (how bad is ignorance)😔

[Jeff Pollard]

Hi,

  The setup file should get automatically run when the HAL file is run.

  You should only have to go through the configuration chooser, select CRAMPS, then run it.

  The INI and HAL files will do the rest, including run the setup files. 

  This assumes you use an older version of Machinekit.

  I do not know what the current version requires as far as setup.sh files is concerned.

  To make it operational, you need to make sure that you have met any HAL requirements that the CRAMPS configuration may setup (like jumper an output and input for a safety switch).

Jeff

[Roberto Gonzalez]

Hi Jeff.

Thanks a los for the info anda the help, I will try this way.