I have a diode laser that uses Lightburn laser software. This laser has a basic atmega328 Arduino UNO compatible controller board running grbl firmware. Lighburn wants positive workspace but grbl is negative coordinate workspace which is what you want for cnc milling operations. These are some instructions to set a coordinate offset so grbl can be used with Lightburn. I didn’t want to remember to use a offset so instead modified the grbl firmware to use positive workspace. This is my Dropbox link to the modified firmware. It is based on the latest grbl 1.1h source code. The positive workspace code is originally found in the 32bit version of grbl-LPC which I used to modify the 8 bit atmega328 grbl version. In the build directory is the compiled hex files that can be uploaded to a Arduino UNO. This firmware also has homing enabled for X and Y axis. No Z axis homing since my laser doesn’t have one. Machine homing switches should be used for this positive workspace firmware version to work properly.