[Machinekit] How to connect 8 Stepper Motors to a BBB?

[Florian Rist]

Hi,
I recently built a machine using Machinekit, a Beaglebone Black and 6
stepper motors. I didn't manage to find proper documentation on where to
find the step and dir signals for the steppers so I looked at the
schematics of the Cramps cape and wired up my six drivers in the same way
and followed a cramps tutorial. I felt a bit uncomfortable, but it worked.

Now I need to connect 8 stepper drivers and fell lost.

I guess I need to load a properer device tree overlay, but which one?


See you
Flo

[Alexander Rössler]

You can connect the dir and step pins to any gpio pin you want. However,
you will require stepper driver to drive your steppers. Using the BBB
universal IO device tree overlays you can change the pin configuration
at run-time. See:
https://github.com/cdsteinkuehler/beaglebone-universal-io
and https://github.com/strahlex/BBIOConfig

Regards,
Alexander

Post by Florian Rist
Hi,
I recently built a machine using Machinekit, a Beaglebone Black and 6
stepper motors. I didn't manage to find proper documentation on where to
find the step and dir signals for the steppers so I looked at the
schematics of the Cramps cape and wired up my six drivers in the same way
and followed a cramps tutorial. I felt a bit uncomfortable, but it worked.
Now I need to connect 8 stepper drivers and fell lost.
I guess I need to load a properer device tree overlay, but which one?
See you
Flo

--
Alexander

[Charles Steinkuehler]

Yes, you can use any available GPIO pins for the two additional
motors, just make sure they are set to be outputs (typically done in
setup.sh if you're starting with the default CRAMPS configuration).

I have run with 9 steppers, using a CRAMPS board and a CRAMP3
expansion board:

https://github.com/cdsteinkuehler/bobc_hardware/tree/CRAMPS/CRAMP3

https://oshpark.com/shared_projects/u7Go5rog

If you want to use the same pinout, the pins for the three additional
axis are listed as text comments on the CRAMPS schematic, split
between P303 (U axis) and P503 (V and W axis), but you can use any
available I/O pins.

Post by Alexander Rössler
You can connect the dir and step pins to any gpio pin you want. However,
you will require stepper driver to drive your steppers. Using the BBB
universal IO device tree overlays you can change the pin configuration
https://github.com/cdsteinkuehler/beaglebone-universal-io
and https://github.com/strahlex/BBIOConfig
Regards,
Alexander

Post by Florian Rist
Hi,
I recently built a machine using Machinekit, a Beaglebone Black and 6
stepper motors. I didn't manage to find proper documentation on where to
find the step and dir signals for the steppers so I looked at the
schematics of the Cramps cape and wired up my six drivers in the same way
and followed a cramps tutorial. I felt a bit uncomfortable, but it worked.
Now I need to connect 8 stepper drivers and fell lost.
I guess I need to load a properer device tree overlay, but which one?
See you
Flo

--
Charles Steinkuehler
***@steinkuehler.net

[matthew venn]

Is it possible to use any pin as GPIO for step generation via PRUs? I've
done a bit of research and it looked to me like there were only specific
pins capable of the fast step gen.
Cheers,
Matt

Post by Charles Steinkuehler
Yes, you can use any available GPIO pins for the two additional
motors, just make sure they are set to be outputs (typically done in
setup.sh if you're starting with the default CRAMPS configuration).
I have run with 9 steppers, using a CRAMPS board and a CRAMP3
https://github.com/cdsteinkuehler/bobc_hardware/tree/CRAMPS/CRAMP3
https://oshpark.com/shared_projects/u7Go5rog
If you want to use the same pinout, the pins for the three additional
axis are listed as text comments on the CRAMPS schematic, split
between P303 (U axis) and P503 (V and W axis), but you can use any
available I/O pins.

Post by Alexander Rössler
You can connect the dir and step pins to any gpio pin you want. However,
you will require stepper driver to drive your steppers. Using the BBB
universal IO device tree overlays you can change the pin configuration
https://github.com/cdsteinkuehler/beaglebone-universal-io
and https://github.com/strahlex/BBIOConfig
Regards,
Alexander

Post by Florian Rist
Hi,
I recently built a machine using Machinekit, a Beaglebone Black and 6
stepper motors. I didn't manage to find proper documentation on where

to

Post by Alexander Rössler

Post by Florian Rist
find the step and dir signals for the steppers so I looked at the
schematics of the Cramps cape and wired up my six drivers in the same

way

Post by Alexander Rössler

Post by Florian Rist
and followed a cramps tutorial. I felt a bit uncomfortable, but it

worked.

Post by Alexander Rössler

Post by Florian Rist
Now I need to connect 8 stepper drivers and fell lost.
I guess I need to load a properer device tree overlay, but which one?
See you
Flo

--
Charles Steinkuehler

[Charles Steinkuehler]

Going through old emails, it doesn't look like this ever got answered.

You can use any available GPIO pin for a PRU output with very minimal
performance overhead vs. using a direct PRU output signal. Using any
arbitrary GPIO pin will not cause any significant issues until your
update rates get into the few hundred nS range (or above a few MHz
step frequency), at which point you might want to use the direct PRU
outputs.

...but if you're needing to run that fast, you'll probably want to
tweak the PRU code as well, which was written more for flexibility
than for raw speed (I generally assumed step rates below 500 KHz or so
when writing the PRU code and HAL driver, you'd want to do things
differently if you need to run significantly faster).

Is it possible to use any pin as GPIO for step generation via PRUs? I've done a
bit of research and it looked to me like there were only specific pins capable
of the fast step gen.
Cheers,
Matt
Yes, you can use any available GPIO pins for the two additional
motors, just make sure they are set to be outputs (typically done in
setup.sh if you're starting with the default CRAMPS configuration).
I have run with 9 steppers, using a CRAMPS board and a CRAMP3
https://github.com/cdsteinkuehler/bobc_hardware/tree/CRAMPS/CRAMP3
<https://github.com/cdsteinkuehler/bobc_hardware/tree/CRAMPS/CRAMP3>
https://oshpark.com/shared_projects/u7Go5rog
<https://oshpark.com/shared_projects/u7Go5rog>
If you want to use the same pinout, the pins for the three additional
axis are listed as text comments on the CRAMPS schematic, split
between P303 (U axis) and P503 (V and W axis), but you can use any
available I/O pins.

Post by Alexander Rössler
You can connect the dir and step pins to any gpio pin you want. However,
you will require stepper driver to drive your steppers. Using the BBB
universal IO device tree overlays you can change the pin configuration
https://github.com/cdsteinkuehler/beaglebone-universal-io

<https://github.com/cdsteinkuehler/beaglebone-universal-io>

Post by Alexander Rössler
and https://github.com/strahlex/BBIOConfig

<https://github.com/strahlex/BBIOConfig>

Post by Alexander Rössler
Regards,
Alexander

Post by Florian Rist
Hi,
I recently built a machine using Machinekit, a Beaglebone Black and 6
stepper motors. I didn't manage to find proper documentation on where to
find the step and dir signals for the steppers so I looked at the
schematics of the Cramps cape and wired up my six drivers in the same way
and followed a cramps tutorial. I felt a bit uncomfortable, but it worked.
Now I need to connect 8 stepper drivers and fell lost.
I guess I need to load a properer device tree overlay, but which one?
See you
Flo

--
Charles Steinkuehler
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https://github.com/machinekit
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Charles Steinkuehler
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