grbl-MegaPi (Makeblock LaserBot Firmware)

Upgrading the LaserBot firmware has really brought this laser engraver back to life! It rivals some of my new engravers and works well.

Latest stable for LaserBot: https://github.com/porrey/grbl-MegaPi/releases/latest

How to upgrade (quick path)

1. Open the latest stable release:
   • https://github.com/porrey/grbl-MegaPi/releases/latest
2. Download source ZIP, then install the grbl folder as an Arduino library.
   • Arduino IDE: Sketch > Include Library > Add .ZIP Library...
3. Open File > Examples > grbl > grblUpload.
4. Select Arduino Mega or Mega 2560 and upload to your MegaPi.

Planned distribution path: Arduino Library Manager support (see doc/markdown/distribution.md for submission/release steps).

This repository is a Grbl-Mega fork configured for the Makeblock LaserBot and its MegaPi (ATmega2560) controller.

The goal is to replace the original legacy firmware/software stack with a standard Grbl workflow so the LaserBot can be used with modern software like LightBurn.

Base Grbl-Mega documentation is available here:
https://github.com/gnea/grbl-Mega/blob/edge/README.md

Makeblock LaserBot + MegaPi

LaserBot

The Makeblock LaserBot is a 2-axis laser engraver/cutter platform. In this firmware:

• X/Y motion is fully supported with LaserBot pin mapping.
• Laser power uses Grbl spindle/laser control (M3, M4, M5, S values).
• Homing and limit behavior are configured for LaserBot endstops.

MegaPi board

The MegaPi is based on the ATmega2560, so it can be programmed directly from the Arduino IDE as an Arduino Mega-class target.

This fork includes a dedicated MegaPi board map and LaserBot defaults:

• DEFAULTS_MEGAPI_LASERBOT enabled in grbl/config.h
• CPU_MAP_2560_MEGAPI_BOARD enabled in grbl/config.h
• LaserBot-specific pin map in grbl/cpu_map.h
• LaserBot driver/limits/laser PWM handling in grbl/megapi.c

See MegaPi Documentation for more information.

LaserBot defaults in this firmware

Key machine defaults compiled into this build include:

• Baud: 230400
• Work area defaults: X 340 mm, Y 360 mm
• Laser mode enabled by default ($32=1)
• Homing enabled by default ($22=1)
• PWM range aligned for LaserBot laser control (S0 to S255)

These come from the DEFAULTS_MEGAPI_LASERBOT profile in grbl/defaults.h.

Build and flash firmware with Arduino IDE

The LaserBot uses the standard Arduino upload workflow.

1) Download this firmware

Either:

• Clone:
  • git clone https://github.com/porrey/grbl-MegaPi.git
• Or download ZIP from GitHub and extract it.

2) Install the Grbl library into Arduino IDE

1. Copy the repository's grbl folder into your Arduino libraries folder.
   • Typical location: Documents/Arduino/libraries/grbl
2. Restart Arduino IDE.

3) Open the upload sketch

In Arduino IDE:

1. Open File > Examples > grbl > grblUpload
2. This loads: grbl/examples/grblUpload/grblUpload.ino

4) Select board and port

In Tools:

• Board: Arduino Mega or Mega 2560
• Processor: ATmega2560 (if shown)
• Port: Select the LaserBot serial port

5) Flash firmware

Click the standard Upload button in Arduino IDE.

That is all that is required to flash the LaserBot.

LightBurn setup

After firmware upload, configure LightBurn with the provided device profile.

1) Download and install LightBurn

Get LightBurn from: https://lightburnsoftware.com

2) Import the LaserBot device profile

1. Open LightBurn.
2. Go to Devices.
3. Click Import.
4. Select:
   • LightBurn/Laserbot.lbzip
5. Finish the import wizard and connect to the LaserBot serial port.

The Laserbot.lbzip profile includes the key connection and machine parameters needed for this firmware.

3) Open included sample jobs

This repository includes LightBurn samples in LightBurn/:

1. Test.lbrn2
   Text engraving test file.

2. Cut-Test.lbrn2
   20 cm x 20 cm cut test pattern.

3. mando.lbrn2
   Image etching example.

LaserGRBL setup

You can also run this firmware with LaserGRBL instead of LightBurn.

1) Download and install LaserGRBL

Download from: https://lasergrbl.com

2) Connect to the LaserBot

1. Start LaserGRBL.
2. Select the LaserBot COM port.
3. Set baud rate to 230400.
4. Click Connect.

3) Configure machine profile/settings

Use these baseline values for this firmware:

• Controller type: Grbl
• Work area: X 340 mm, Y 360 mm
• Laser mode enabled: $32=1

Optional but recommended:

• Home the machine ($H) before jobs.

Enable Soft Limits [$20=1] (optional)

Enable soft limits in LightBurn

Soft limits are disabled by default in this firmware ($20=0), so enable them after setup if you want Grbl to alarm on out-of-range moves.

1. Connect to the LaserBot in LightBurn.
2. Open the Console panel.
3. Send:
   • $20=1
4. Confirm by sending $$ and checking that $20=1 is reported.

Soft limits require homing and valid travel settings ($130, $131).

Enable soft limits from Arduino IDE

You can set the same option from Arduino IDE using Serial Monitor.

1. Open Tools > Serial Monitor.
2. Set line ending to Newline and baud to 230400.
3. Send:
   • $20=1
4. Send $$ to verify that $20=1 is saved.

Soft limits are stored in Grbl settings, so this only needs to be done once per controller reset/config reset workflow.

Enable soft limits in LaserGRBL

You can also enable soft limits directly from LaserGRBL.

1. Connect to the LaserBot in LaserGRBL.
2. Open the Console area.
3. Send:
   • $20=1
4. Send $$ and confirm $20=1 is shown in the settings list.

Soft limits require homing and valid travel settings ($130, $131).

Machine travel limits and 5 mm safety buffer

This firmware is configured with a 5 mm safety buffer on each axis:

• $130=340 (X travel)
• $131=360 (Y travel)

The machine can physically travel to about X=345 and Y=365, but the configured values intentionally stop 5 mm short to reduce overtravel risk.

Set and verify travel limits ($130, $131) in LightBurn and LaserGRBL

If you want to expand the limits and remove the 5 mm safetly buffer on each axis, you can reconfigure the settings using the serial interface through the software or the Arduino IDE.

1. Connect to the controller.
2. Send:
   • $130=345
   • $131=365
3. Send $$ and verify $130 and $131.

Update software work area after changing travel limits

If you change the firmware limit settings the software will need to be updated too.

• LightBurn: Open Device Settings and set work area to X 345 mm / Y 366 mm (or your chosen values), then save.
• LaserGRBL: Open machine profile/settings and set work area to X 345 mm / Y 365 mm (or your chosen values), then save.

LaserBot support summary (what this fork changes)

This fork adds and enables the pieces needed to run a Makeblock LaserBot as a Grbl laser machine:

1. LaserBot/MegaPi build profile enabled
   • grbl/config.h enables MegaPi CPU map and LaserBot defaults.
2. LaserBot hardware pin mapping
   • grbl/cpu_map.h defines LaserBot motion, enable, endstop, and laser PWM pins.
3. MegaPi board-specific runtime support
   • grbl/megapi.c initializes drivers, reads LaserBot limits, and controls laser PWM behavior.
4. Laser-oriented defaults
   • grbl/defaults.h sets machine travel, speeds, homing, baud, and laser mode defaults for LaserBot.
5. Laser command behavior compatibility
   • Laser power behavior is adapted for MegaPi/LaserBot handling in core motion/spindle flow.

Together, these changes modernize the LaserBot workflow and allow practical use with current host software, especially LightBurn.

Maintainer discoverability checklist

Repository settings that should be configured on GitHub:

• Description: Makeblock LaserBot firmware upgrade for MegaPi using Grbl + LightBurn workflow
• Topics: laserbot, makeblock, megapi, grbl, firmware, lightburn

See also:

• Release/submission workflow: doc/markdown/distribution.md
• Community announcement templates: doc/markdown/community_announcement.md