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This is the development branch for Grbl v1.0's upcoming release. In general, the new features here are beta, so use with caution. If you'd like to help, please report any bugs or oddities that you find! Thanks!

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Grbl is a no-compromise, high performance, low cost alternative to parallel-port-based motion control for CNC milling. It will run on a vanilla Arduino (Duemillanove/Uno) as long as it sports an Atmega 328.

The controller is written in highly optimized C utilizing every clever feature of the AVR-chips to achieve precise timing and asynchronous operation. It is able to maintain up to 30kHz of stable, jitter free control pulses.

It accepts standards-compliant g-code and has been tested with the output of several CAM tools with no problems. Arcs, circles and helical motion are fully supported, as well as, all other primary g-code commands. Macro functions, variables, and most canned cycles are not supported, but we think GUIs can do a much better job at translating them into straight g-code anyhow.

Grbl includes full acceleration management with look ahead. That means the controller will look up to 18 motions into the future and plan its velocities ahead to deliver smooth acceleration and jerk-free cornering.

• Licensing: Grbl is free software, released under the GPLv3 license.

• For more information and help, check out our Wiki pages! If you find that the information is out-dated, please to help us keep it updated by editing it or notifying our community! Thanks!

• Lead Developer [2011 - Current]: Sungeun(Sonny) K. Jeon, Ph.D. (USA) aka @chamnit

• Lead Developer [2009 - 2011]: Simen Svale Skogsrud (Norway). aka The Originator/Creator/Pioneer/Father of Grbl.

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Official Supporters of the Grbl CNC Project

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##Update Summary for v1.0c

• IMPORTANT: Your EEPROM will be wiped and restored with new settings. This is due to the addition of two new spindle speed '$' settings.

• Altered limit pin status reports from Lim:000 to Pin:000|0|0000, where the | delimiters separate the new probe state and control pin states. Each new field may be disabled by the $10 Grbl setting. NOTE: Commenting REPORT_ALL_PIN_STATES in config.h reverts to old Lim: reports, if needed.

• New safety door parking motion as a compile-option. Grbl will retract, disable the spindle/coolant, and park near Z max. When resumed, it will perform these task in reverse order and continue the program. Highly configurable. See config.h for details.

• New '$' Grbl settings for max and min spindle rpm. Allows for tweaking the PWM output to more closely match true spindle rpm. When max rpm is set to zero or less than min rpm, the PWM pin D11 will act like a simple enable on/off output.

• Updated G28 and G30 behavior from NIST to LinuxCNC g-code description. In short, if a intermediate motion is specified, only the axes specified will move to the stored coordinates, not all axes as before.

• NOTE: Arduino Mega2560 support has been moved to an active, official Grbl-Mega project. All new developments here and there will be synced when it makes sense to.

• A few bug fixes and lots of refactoring to make the code more efficient and flexible.

List of Supported G-Codes in Grbl v0.9 Master:
  - Non-Modal Commands: G4, G10L2, G10L20, G28, G30, G28.1, G30.1, G53, G92, G92.1
  - Motion Modes: G0, G1, G2, G3, G38.2, G38.3, G38.4, G38.5, G80
  - Feed Rate Modes: G93, G94
  - Unit Modes: G20, G21
  - Distance Modes: G90, G91
  - Arc IJK Distance Modes: G91.1
  - Plane Select Modes: G17, G18, G19
  - Tool Length Offset Modes: G43.1, G49
  - Cutter Compensation Modes: G40
  - Coordinate System Modes: G54, G55, G56, G57, G58, G59
  - Control Modes: G61
  - Program Flow: M0, M1, M2, M30*
  - Coolant Control: M7*, M8, M9
  - Spindle Control: M3, M4, M5
  - Valid Non-Command Words: F, I, J, K, L, N, P, R, S, T, X, Y, Z

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Grbl is an open-source project and fueled by the free-time of our intrepid administrators and altruistic users. If you'd like to donate, all proceeds will be used to help fund supporting hardware and testing equipment. Thank you!