MRRF: ARM-Based CNC Controllers


8-bit microcontrollers are the standard for RepRap electronics, but eventually something better must come along. There has been a great deal of progress with ARM-based solutions, and of course a few of these made a showing at the Midwest RepRap Festival.

First up is [Mark Cooper], creator of Smoothieboard, the ultimate RepRap and CNC controller. It’s an ARM Cortex-M3 microcontroller with Ethernet, SD card, and up to five stepper drivers. It had a Kickstarter late last year and has just finished shipping all the rewards to the backers. In our video interview, [Mark] goes over the functions of Smoothieboard and tells us about some upcoming projects: the upcoming Smoothiepanel will feature a graphic LCD, SD card, rotary encoder and buttons, all controlled over USB by the Smoothieboard.

Next up is [Charles] with a whole bunch of CNC capes for the Beaglebone. By far the most impressive board was a huge I/O expander, motor driver, and everything controller for a Beaglebone featuring – get this – three parallel port interfaces. This was a one-off board costing thousands of dollars, but [Charles] did show off a few smaller and more practical boards for Beaglebone CNC control. Here’s a link to [Charles]’ capes.

Videos below.

23 thoughts on “MRRF: ARM-Based CNC Controllers

  1. Love the CNC capes for BeagleBone, the best ARM board around. If it were not for the small problem that it has been months no distributor stocks it. Shipment is estimated in July, if you can trust them. Absolutely impossible to develop for a board that nobody knows when and if will be available.
    Somebody should Kickstart a second source.

    1. Mr. Steinkuehler:

      I’ve got an BB (white) that’s just collecting dust. I guess a CNC machine is a good use for it as any. Which cape would you recommend especially for use with LinuxCNC?


  2. I can’t count how many times you mentioned the smoothieboard in the last month, and it’s not even for sale outside some kickstarter. Why no mention of TinyG? It seems considerably further developed and you can actually buy one, today, with real money.

  3. I think this is great.
    I saw the smoothieboard a little while back. The only thing that confuses me about these things is the inclusion of stepper drivers on these boards when they are geared toward CNC machines, which typically require larger stepper motors (with larger drivers).

    I would much rather see some standalone CNC controllers with pulse/step outputs, perhaps along with paired open source stepper drivers that connect to them. I think it would be a lot more generally useful this way, and shouldn’t drive the price up prohibitively.

    1. I agree – it would be nicer to have generic outputs to a header. Then you can mount whatever driver you want. Also nice if you manage to burn out a driver. Just replace the blown module, no SMD repair work needed.

    2. I think the original Smoothieboard was like this. It’s basically an ARM dev. board with a bunch of Pololu stepper drivers connected via breadboards. I believe the software still works with this config.

  4. until they remove the drivers from the board it will not be a good design. At a minimum the drivers should be on a modular plug to be easily replaced.

    and don’t even get me started on supporting servo’s over steppers.

    1. Well, from what I’ve seen so far, most hobby CNC machines are stepper-based. Servomotors are a lot more expensive.

      You can get servo amps that read step/direction pulses, which is trivial to extract such a signal using header pins.

    2. Previous ARM reprap electronics were twice as expensive ( yes, twice, and not OSHW ).
      We concentrated on low-cost, to make sure the board would be priced in a similar range to the current reprap electronics, but at the same time you get much more power, many more features, and an easier to use/configure board. And ethernet. And a laser/cnc-milling capable firmware. For a similar price. I think it’s a good design, it just may not have been designed for the goals you’d like. But lots of people are ok with cheap+integrated, we just listened to them.

  5. ” Smoothieboard, the ultimate RepRap and CNC controller”

    If it is OH SO ultimate, then why are the wimpy stepper drivers soldered onboard instead of being on daughterboards?
    This is the exact opposite of ultimate, since it is about as flexible as a Apple product.

    1. If you think it isn’t flexible, you must have never looked at the firmware :)
      Joke aside, on-board drivers are cheaper, better cooled, and with modern drivers, quite well protected.
      If you need to use external drivers, you can just plug them into the board, many have done that. We have a $100 board with only 3 integrated drivers that is perfect for this.

      If you want to use pololus, panacutt is going to release a smoothie-compatible board that will have slots for them. We just went for compact/cheap/well-cooled, others can and will propose other options, what’s really important here is the firmware :)

  6. It seems that mark from Uberclock isn’t responding to emails or shipping out packages that customers have paid $170+ for. I find this highly unprofessional as I ordered the board nearly a week ago and it was marked as shipped a few days ago but hasn’t been handed off to the post office in that time. Just a word of warning for anyone else that is tempted by what should be a great control board. But their ‘team” could use some serious customer service work.

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