Help with CNC machine design from cero.... firmware develop

[rald]

Hello Experts,

I have couple of weeks searching about how to build CNC machine (milling) but I can find a lot about the infra (AXIS X, Y ,Z) but I can not understand or find any firmware for a PIC to send and execute the machine.

I have 3 steppers controlled by the PIC18F4550 and also I have some software to use but I don't get what do I need to configure into the PIC to this understand what to do.

Can someone help with this?

please.
thanks.

[temtronic]

First thing to do is post the make/model/part numbers of the CNC machine you're using BUT if this is a 'homemade' unit you're probably on your own.
There may be some CNC 'standards' for data communications but without more details I can't help you though I do have a 'CNC machine run by a 4550' sitting here collecting dust. One of those 'cup of coffee' challenges I did about 2 years ago.


jay

[Ttelmah]

The 'standard' for CNC, is G-code. This was the language that 40 years ago, things like HP plotters used to move the pens, which was then expanded to add controls for more axes, more complex shapes etc..

How complex the interpreter needs to be, will depend on what program you are going to use to generate the code, and what features you need.

You are almost certainly not going to fit a G-code translator for complex codes into your PIC. I'd move your stepper control into another simpler PIC, and then (assuming you are using the 4550 to give USB), do the G-code translation in the 4550, using perhaps SPI to control the second chip. I'd actually consider a faster PIC like a PIC32, for the interpreter, since it becomes surprising how much work is involved. I've done them in the past, in Texas 32bit chips, with a PIC doing the mechanical control.

There are several dozen threads running on the web, for PIC G-code interpreters, and some basic ones have been published. Have a look at them. A 'full featured' G-code interpreter, is probably perhaps 50* as complex as the basic stepper control code....

The simplest way to put together a CNC machine, is to forget the PIC. Just use an embedded PC, running Mach-3, using a SmoothStepper board to control the motors.

[Rocket]

There is a nice DIY CNC option using the PIC18F4550 found at http://www.planet-cnc.com/index.php?page=diy

If a PCB is needed in South Africa, I have a few spare boards.
_________________
J.I.L.

[mmprestine]

Just to get an idea of how complex a G-code interpreter is take a look at this open source project.

http://smoothieware.org/

https://github.com/Smoothieware