Avayan’s CNC Electronics Overview

My electronics are ready to go. Everything except one board is of my design, and I am proud to report that as of today it is all working.

The parallel port board is the only thing I bought. It is a C10 breakout board from CNC4PC. You can find more information on the board here: http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=45.

On the lower left you can see my AE-PWR1 Dual DC Switching regulator converter board. I use this board to convert from 24V to 3.3V and 5V. As it turns out, the C10 requires 5V. But my stepper drivers use an MSP430 microcontroller, so they require 3.3V. The AE-PWR1 worked beautifully to get me the rails I needed. Could I have used conventional linear regulators such as the 7805? Sure! But I had the AE-PWR1 ready to go, so why not? Plus this is way more efficient and will get less hot than the linear counterpart.

At the center left you can see my new AE-PWRPlane. http://www.avayanelectronics.com/Products/AE-PWRPlane/ae-pwrplane.html. This little board allowed me to easily route the 24V from the power supply to the switching regulator and three stepper driver boards. Since it is a dual plane, it also allowed me to route the 3.3V from the switcher output into the three stepper drivers as well as the opto coupler board. I could have used the output terminals on the AE-PWR1. Either would have worked perfectly.

At the top you can see the three stepper drivers. These I have not released into the public yet as I need to validate the design a little bit more. However, they consist of two DRV8828 single H Bridge drivers from TI and an MSP430F1612 microcontroller. The firmware will allow up to 512 microsteps to be generated by using the on board dual DAC channels. This however, is too much resolution even for this project, so I am using way less than that.

The last board is the one I am least proud of as it is an ugly protutype but it works perfectly well and since I do not see myself building more of this, it will have to do. This is a conversion board I needed to place in between the C10 parallel board and the microcontrollers. It consists of a series of optocouplers which I use to convert from 5V to 3.3V. So in essence, they are level shifters. Yes, ideally I should use level shifters but the optocouplers offer the advantage of isolating the stepper drivers from the PC. So if something happens (and I hope it does not), then the PC should be safe.

10 comments for “Avayan’s CNC Electronics Overview

  1. Robert
    July 18, 2012 at 9:37 pm

    Hello and congrats!

    Nice set up! Any chance of releasing your design?

    I like Ti’s DRV line of stepper drivers. I’ve been trying to design a board based on the DRV8432. However it’s much harder than I thought it would be. The main reason is my lousy SMD soldering skills, and my inabilty to get my current setup tuned properly so I can mill pcb’s.

    Your article “Choosing Components for the DRV8811 Stepper Driver” was very helpfull thank you. I am still somewhat confused as this is my first attempt at such a difficult design.

    Thanks again for your articles. Please keep em coming! I need all the help I can get 😉

    A.K.A SubMicro

  2. avayan
    July 19, 2012 at 1:54 am

    Hi Robert (AKA SubMicro),

    There is not much to my setup, but I guess I can indeed document what it all is. In essence what you will find on this setup is one of my CNCBridge boards which connects to the PC’s parallel port and level shifts from 5V to 3.3V if necessary, connected to some of my stepper drivers (there are some to choose such as the STPR1, STPR8811, MegaMotor I, MegaMotor II and soon to be released STPR8818-TP and STPR8825-TP). I am also using a power distribution board and a power supply board to derive 5V, 3.3V, etc.

    On this article I was using the MonstroStep which is a board I was never able to document. It is just too complex and I never seem to find the time to sit down and write down the five or six postings I would need to get down in order for it all to make sense. It is a stepper driver consisting of a microcontroller and 2 5A H Bridges, so you can basically do up to 5A with 512 degrees of microstepping. Kind of insane, if you ask me, when 32 degrees of microstepping are more than plenty!

    I am about to release two new driver boards which I will be documenting in the following weeks and they have been designed exclusively for CNC equipment, so I better explain how it all works as well. Thanks for bringing it up!

    Most of these boards are documented on http://www.avayanelectronics.com and can be purchased assembled from http://www.driverdudes.com in case anybody is looking for them. I realize SMT soldering is not as simple as we would all like. There are ways around it, but of course it still takes some effort and a little bit of a learning curve. Once you know it, though (and you have the right tools, might I add) it is not as hard as it seems. That’s why I got my buddies at driverdudes.com to take care of that nuisance taken care of!

    Good luck with your CNC project and let me know if there is anything I can help you with!

  3. avayan
    July 19, 2012 at 1:56 am

    OK, a fix!

    On this article I am using a parallel board I bought from the web, as detailed above. However, I eventually created my own parallel port board which you can see here: http://www.avayanelectronics.com/Products/AE-CNCBridge/ae-cncbridge.html

  4. Robert
    July 19, 2012 at 2:48 am

    Thank for the quick reply. I checked out your other boards, and you are very talented.

    I need to drive 3 nema 17 BiPolar stepper motors and a maximum of 1.5A per phase. I was thinking of trying one of your STPR8811 with a DRV8818. Where can I get that heatsink?


    • avayan
      July 19, 2012 at 3:24 am

      Thanks for the Kuddos and the kind words! Always great to hear such great compliments!

      You can find that heat sink on Digikey, but don’t even bother. With DRV8818 you can run at 2.5A without using a heat sink, so at 1.5A you will have zero issues!

      If you still want to read on the heat sink, you can find it on Digikey under part number DA-T268-101E-ND (http://www.digikey.com/product-detail/en/DA-T268-101E/DA-T268-101E-ND/2207648)

  5. Robert
    July 19, 2012 at 2:57 am

    Well I decided to go for it and your out of stock!! arrrg! Will you be getting any soon?

    • avayan
      July 19, 2012 at 3:21 am

      Robert, send an email to Nick@driverdudes.com. I am positive he can get you equipped in a very short time. He assembles these boards as the orders come, but he is pretty quick and makes sure the boards are tested before they ship.

  6. Robert
    July 19, 2012 at 8:32 pm


    I’m sorry I thought DriverDudes was your site. I’ll shoot them an e-mail. Thanks again.

    A.K.A. Robert

  7. December 22, 2012 at 5:18 pm

    Hey Avayan

    When are you going to release the AE-CNC8825-TP? I would love to try it out on my X2.


  8. December 22, 2012 at 5:20 pm

    p.s. Merry Xmas!

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