Loading GRBL on the Arduino Uno

This section is for the post build uploading GRBL onto the Arduino. There are many versions available, but I will be focused on the most stable version, which was completely gone through and revised by my GURU, Larry Mayberry who we tragically lost in 2019. Also know as LarryM on the inventables forum. All information is copied from or derived from Larry with his permission before he pasted. Larry will always live on in every machine I make.

How to use Xloader to load a new version of grbl into the Arduino/X-controller.

The left screenshot shows the window that Xloader displays when it starts.

Enter the file path or browse to the .hex file that you would like to load into the Arduino/X-controller.

Select the device type you are going to load into (Uno/ATmega328 for the Arduino/X-controller).

Select the COM port where your Arduino/X-controller is attached.

The baud rate should be 115200.

Press the "Upload" button.

When the .hex file has been loaded into the Arduino/X-controller the right screenshot will show the size of the file uploaded, or an error message if the upload fails.

Vectric Post Processor Location:

If you use the default install directories, then the private post processors should be moved to this directory:


Example: for Vcarve Pro version 8.5 the directory would be:
C:\ProgramData\Vectric\VCarve Pro\V8.5\My_PostP

Designs By Phil Rotary Post Processor: 

GRBL Version 1.1f (Positive Build)

I designed this post processor from scratch. It allows you to use degree output from Vcarve with a properly set up rotary (see Rotary Demon Training page). Should be zeroed on rotation axis. No need to recalculate steps per mm for every job. This will be used when using my Demon Rotary Switch TM.

This is a version of grbl that supports both spindle and laser based on grbl version 1.0c from Inventables. It contains the original changes by Andrew L. Sandoval to produce grbl version 0.9g for J Tech as well as some optimizations that I included for the laser functions.

Thanks to Jeff @picengravertoo (Who tragically died this year) and John @JohnChamplain for their help in testing this new version.

There are two build versions.

The first version (release 11/12/2016) is the base version for spindle and laser.

The second version (release 9/1/2017) is a modification of the first release to change the Dwell (G4) to allow smaller increments for Dwell.

The first version uses the standard 50ms floor with 50ms steps for the dwell and the second version uses a 1ms floor and 1ms steps.

9/1/2017 - added version with Dwell change
10/12/2016 - update (bug fix) ghosting
9/28/2016 - original release

First time users - you really need to read the readme.pdf


The following is all copied directly from Larry's posts and are his words.

This is also from a Larry Mayberry post.

(click to enlarge)

Vectric Products Post Processor files: 

I highly recommend using the 1.0c GRBL above. It is very stable and safe with lasers. please read the following message (click on picture below) BEFORE deciding to use 1.1f. - PHIL JOHNSON



Update 12/29/2015

It appears that this doesn't work on Windows 10. I don't have Windows 10 so I can't try it, but another forum member tried it and it didn't work for him.

Updated 12/12/2015

Revised method for uploading a .hex file to the Arduino. This is an alternate method for uploading if you have difficulties with Xloader. This version prompts for the COM port and filename.

**** Readme file 12/12/2015 ****

To use this .zip file to load a hex file into your Arduino you first need to copy your .hex file to the same directory where you unzipped this file.

Double click the AVRDUDE_Upload.bat file and a command prompt window will appear.

The first thing the command prompt window will ask for is the port that the Arudino is attached to. For example, COM1. Enter the port name on your system where the Arduino is attached.

Next the batch file executing will ask for the filename of the .hex file you want to upload. Enter the file name of the .hex file you copied into the location where you unzipped the .zip file.

Now the batch file will upload your .hex file to the Arduino.

Once finished the batch file will pause to let you look at the upload comments. Press the space bar to allow the batch file to terminate once you have examined the upload comments.

Be sure to keep all of these files in the same directory and execute the batch file from the directory where you unzipped the files.

The .HEX file included is grbl version 1.0c from above. (I (Phil Johnson) swapped out the old 0.9J GRBL for the new one above)

NOTE: Easel cannot send files created with these post processors (Easel does NOT do arcs [G2/G3]).

GRBL Version 1.0c For Laser And Spindle