Posts: 14
Joined: Sun Jun 01, 2014 8:26 am

Raspberry Pi CNC

Tue Jul 01, 2014 3:59 am


I know there is already a plethera of posts out there for creating a CNC machine with a Pi. However..........

I have compiled my own kernel and got Linuxcnc EMC2 working on my Pi. However I am new to stepper motors and drive/step pins. I have 3 x Nema17 4 wire bipolar motors and 3 x HG7881 H-Bridge devices. Linuxcnc will only allow the use of 2 Pins on the Pi for step and drive. Could you please let me know how to wire up the Pi to H-Bidge to Nema17? I am lost on the A1,A2,B1,B2 sequencing and how that fits in with a single drive and single step pin on the Pi.

This is the last link in my chain before starting a physical machine build I really hope someone can help me? Thanks in advance!


Posts: 118
Joined: Wed Oct 24, 2012 9:15 pm
Location: Cheltenham, UK

Re: Raspberry Pi CNC

Sat Jul 05, 2014 10:45 pm


I sounds like you need to fill the gap between your Pi and the stepper motors. You might want to start here: for background info (there are other (and better) sources).

You've already got a bunch of H-driver devices and you'll need a big power supply plus a box to keep it all safe from you and itself. Or you could go investigate these modules: ... er-Drivers. These modules will solve the "step/direction" problem and include an "H Bridge driver". If you follow the data sheet links it'll get you to some diagrams that show the computer interface through to the motors.

There are other suppliers for this sort of stuff, you either start with the raw devices, a soldering iron or go with the modules and a screw driver.
Share and Enjoy.

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Posts: 778
Joined: Wed Aug 28, 2013 4:09 pm
Location: UK

Re: Raspberry Pi CNC

Sun Jul 06, 2014 6:27 am

Lots of stuff on YouTube start here >>>>
Can't find the thread you want? Try googling : YourSearchHere

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