Xylotex BareBonesCNC board...

[Peter Gregson]

Hello, 

I am planning to use a BeagleBone Black running machinekit with a BareBonesCNC cape to drive a HobbyCNC Pro 4 stepper driver board.  To do so, I need to know the following:

1.   Is the DB25 connector on the BareBonesCNC card a male or a female?

2.   Can I get a schematic diagram of the BareBonesCNC board?

3.   If I recall correctly, the HobbyCNC Pro 4 has some timing requirements. I have the documentation that I received with it but it doesn't state this requirements that I could find.  So I was planning to use machinelkit's configuration for this board except that it is for using a PC, not the BeagleBone Black.  As a result, I don't know what pulse rates are permitted, nor the setup and hold times for the steps with respect to the direction signals.  I am concerned that the PRUs in the BBB will pulse too fast.  Where would I get this information, or alternatively, how can I use the configuration procedure for a PC to drive the  stepper-driver board to find out the times so that I can correctly configure the .ini and .hal files for the BBB to drive the stepper-driver board?

4.   I have already modified  the .hal file for to get the right DB25 pins to be driven by the right signals, I think.  As an example, the HobbyCNC board requires X-dir to be  pin 2 and X-step to be  pin 3.  The two pins are swapped as compared to the BareBonesCNC pinout.   To do this, I made statement setp hpg.stepgen.01.steppin be 816 and setp hpg.stepgen.01.dirpin be 817.  I changed the entries for the Y, Z and A axes similarly.  What else do I need to change?  What about the PRU entries?

Thank you for your help, and

Best regards,

Peter

[Jeff Pollard]

Hi,

  1) It is female, just like a parallel port on a PC.
  2) No, I don't give out schematics of active parts.  The design is
simple though.  Most signals are just buffered through LVC541 buffers
with RC buffers on the inputs.
  3)  The timing parameters for MachineKit are handled in the INI file. 
Use the numbers appropriate for your driver.  The PRUs can handle
anything a normal drive would require.  In the example INI file on the
BareBones page:

DIRSETUP   =              1000
DIRHOLD    =              20000
STEPLEN    =              500
STEPSPACE  =              4000

  The PRU entries should not need to be modified for the pin swap as long
as you have swapped the 816/817 number in HAL and have the setup and
hold timing set right in INI.  I'm not sure what you thought might need
changing, so can't give a more specific answer.

Jeff