G code interpreter arduino

G code interpreter arduino DEFAULT

If you are thinking or you are in the process of making your own CNC machine, then most likely you will meet with the term GRBL. So in this tutorial we will learn what is GRBL, how to install and how to use it for controlling your Arduino based CNC machine.

Also, we will learn how to use the Universal G-code Sender, a popular open source GRBL controller software.

What is GRBL?

GRBL is an open source software or firmware which enables motion control for CNC machines. We can easily install the GRBL firmware to an Arduino and so we instantly get a low cost, high performance CNC controller. The GRBL uses G-code as input, and outputs motion control via the Arduino .

For better understanding, we can take a look at the following diagram:

GRBL and Arduino CNC Machine Working Principle

From the diagram we can see where the GRBL take place in the “big picture” of the working principle of a CNC machine. It’s a firmware that we need to install or upload to the Arduino so it can control the stepper motors of the CNC machine. In other words, the function of the GRBL firmware is to translate the G-code into motor movement.

Required Hardware

  • Arduino – As we already said, we need an Arduino to install the GRBL. Specifically, we need an Atmega 328 based Arduino board, meaning that we can use either Arduino UNO or Nano.
  • Stepper motors – Obviously, the stepper motors provide the motion of the machine.
  • Drivers – For driving the stepper motors we need drivers and common choices when it comes to smaller DIY CNC machines (using NEMA 14 or 17 steppers) are the A4988 or DRV8825 drivers.
  • Arduino CNC Shield –  For connecting the stepper drivers to the Arduino, the easiest way is to use an Arduino CNC Shield. It utilizes all Arduino pins and provides an easy way to connect everything, the stepper motors, the spindle/ laser, the limit switches, cooling fan etc.

Please note that these are just he basic electronic components we need to understand how a CNC machine works.

Actually, as an example of how everything needs to be connected we can take a look at my DIY CNC foam cutting machine.

Arduino CNC Machine Circuit Diagram - Electronics components

You can check and get the main electronics components needed for building this CNC machine here:

Disclosure: These are affiliate links. As an Amazon Associate I earn from qualifying purchases.

The main tool of this CNC machine is a hot wire which can easily melt or cut through a styrofoam and make any shape we want. For more details how I made the machine and how everything works you can check the particular tutorial.

Arduino CNC Foam Cutting Machine

Nevertheless, we will use this machine as an example throughout this article, because the same working principle applies for any other CNC machine, whether it’s mill or laser.

How to Install GRBL

First, in order to be able to install or upload the GRBL to the Arduino we need the Arduino IDE.

Then we can download the GRBL firmware from github.com.

GRBL - Open source Arduino Firmware for controlling CNC machines

Download it as .ZIP file and then follow these steps:

  • Open the grbl-master.zip file and extract the files
  • Open the Arduino IDE, navigate to Sketch > Include Library > Add .ZIP Library…

Add new library to Arduino IDE

  • Navigate to the extracted folder “grbl-master”, in there select the “grbl” folder and click the open file. Now we have to GRBL as an Arduino Library.

How to install grbl on arduino

  • Next, navigate to File > Examples > grbl > grblUpload. A new sketch will open and we need to upload it to the Arduino board. The code might look weird as it’s just one lines, but not worries, everything happens in the background in the library. So, we just have to select the Arduino board, the COM port and hit that upload button and we are done.

GRBL Configuration

At this point we should configure or adjust the GRBL to our machine. We can do that via the Serial Monitor of the Arduino IDE.  Once we open the Serial Monitor we will get a message like “Grbl 1.1h [‘$’ for help]”. If you cannot see this message, make sure you change the baudrate to 115200.

If we type “$$” we will get a list of commands or current settings, and they appear something like this:

$100=250.000 (x, step/mm)
$101=250.000 (y, step/mm)
$102=3200.000 (z, step/mm)
$110=500.000 (x max rate, mm/min)
$111=500.000 (y max rate, mm/min)
$112=500.000 (z max rate, mm/min)
$120=10.000 (x accel, mm/sec^2)
$121=10.000 (y accel, mm/sec^2)
$122=10.000 (z accel, mm/sec^2)

All of these commands can be or should be adjusted according to our CNC machine. For example the with first command, $100=250.000 (x, step/mm), we can adjust the steps per mm of the machine, or we can specify how many steps the motor should make in order our X axis to move 1 mm.

However, I would suggest to leave these settings as they are. There is an easier way to adjust them according to our machine using the controller software, which we will explain in the next section.

GRBL Controller

So once we have installed the GRBL firmware, now our Arduino knows how to read G-code and how to control the CNC machine according to it. However, in order to send the G-code to the Arduino we need some kind of interface or a controller software which will tell the Arduino what to do. Actually, there are many both open source and commercial programs for that purpose. Of course, we will stick to open source, so as an example we will use the Univarsal G-code Sender.

Universal G-code Sender for controlling the Arduino CNC Machine

How to Use Universal G-code Sender

For this example, I will use the 2.0 Platform version. Once we download it, we need to extract the zip file, go the “bin” folder and open any of the executable “ugsplatfrom” files. This is actually a JAVA program, so in order to be able to run this program, first we need to install JAVA Runtime Environment.

Once we open the Universal G-code sender, first we need to configure the machine, or configure the GRBL parameters shown earlier. For that purpose we will use the UGS Setup Wizard which is much more convenient then manually typing commands through the Serial Monitor of the Arduino IDE.

Universal G-code Sender - GRBL configuration

The first step here is to select the baudrate, which should be 115200, and the port to which our Arduino is connected. Once we connect the Universal G-code sender with the Arduino, in the next step we can check the direction of moving of the motors.

Setting the rotation direction of the motors

If needed, we can reverse the direction through the wizard, or by manually flipping the connection of the motor on the Arduino CNC Shield.

In the next step we can adjust the steps/mm parameter that we mentioned earlier. Here it’s much easier to understand how to adjust it because the setup wizard will calculate and tell us to what value we should update the parameter.

Setting the steps per mm parameter

The default value is 250 steps/mm. This means, that if we click the move “x+” button, the motor will make 250 steps. Now depending on the number of physical steps the motor has, the selected stepping resolution and the transmission type, the machine will move some distance. Using a ruler we can measure the actual movement the machine made and enter that value in the “Actual movement” field. Based on this, the wizard will calculate and tell us to what value we should change the steps/mm parameter.

Setting the steps per mm parameter for CNC machine

In my case, for the DIY CNC machine that I made, the machine moved 3mm. According to this, the wizard suggested to update the steps/mm parameter to a value of 83.

grbl steps calibration

With this value updated the machine now moves correctly, 1 mm in the software mean 1 mm for the CNC machine.

In the UGS console, as we make each action we can see the commands that are executed. We can notice that by updating the steps/mm parameter the UGS program actually sent to the Arduino, or the GRBL firmware the command we mentioned earlier. This was the default value: $100=250.000 (x, step/mm), and now we updated to value of 83 steps per mm: $100=83.

In the next step we can enable the limit switches and test whether they work properly.

CNC machine limit switches setup

Depending whether they are Normally Open or Normally Closed connection, we can also invert them here.

Here it’s worth noting that sometimes we need to disable Z axis limit switch. That was the case with my DIY CNC Foam Cutting machine where I didn’t need the Z axis limit switch and I had to disable it in order to be able to properly home the machine. So, to do that, we need to edit the config.h file which is located in the Arduino library folder (or Documents\Arduino\libraries).

Editing GRBL config file for turning off Z axis limit switch

Here we need to find the homing cycle lines and comment the default set for 3 axis CNC machine and uncomment the setup for 2 axis machines.  In order the changes to take effect we need to save the file and reupload the grblUpload sketch to our Arduino board.

Nevertheless, in the next step we can either enable or disable the homing of the CNC macing.

Homing settings for our CNC machine

Using the “Try homing” button the machine will start moving towards the limit end switches. In case it goes the opposite way we can easily invert the direction.

Finally, in the last step of the Setup wizard we can enable soft limits for our CNC machine.

Enabling soft limits for the CNC machine

The soft limits prevent the machine from moving beyond the set working area.

Conclusion

So, thanks to the GRBL firmware and the Arduino, we can easily setup and get our DIY CNC machine running. Of course, we covered just the basics in this tutorial, but I think that was enough to understand how things work and how to get our first CNC machine up and running.

Arduino Uno and Arduino CNC Shield

Of course, there are many other settings and features available, as the GRBL is really capable CNC controller firmware. The GRBL documentation explains all of that in details, so you can always check them on their wiki page on github.com.

Also, there are many other open source GRBL controller programs like the Universal G-code Sender, and here are few: GRBLweb (Web Browser), GrblPanel (Windows GUI), grblControl (Windows/Linux GUI), Easel (Browser based) etc. You should explore them and see which one suits you the best.

Categories TutorialsSours: https://howtomechatronics.com/tutorials/how-to-setup-grbl-control-cnc-machine-with-arduino/

Arduino GCode Interpreter

This page describes something which is no longer the most recent version. For the replacement version see: G-code

This page has been flagged as containing duplicate material that Darwin/Arduino GCode Interpreter also attempts to cover.
These pages should be merged such that both pages do not attempt to cover the duplicate topics.

This page has now been superseded. For the up-to-date one, see here.

Introduction

G-Code is a commonly use language to control CNC machines. G-Code is a light-weight, simple to parse format, designed to be able to run on modest hardware, such as the Arduino loaded with this firmware (in this case). It is a format that is prepared in advance and created from the digital design files (CAD files).

Several software packages can generate G-Code, so using this firmware allows you a degree of flexibility.

Files

The G-Code firmware source is available from SourceForge as part of the RepRap Arduino firmware package. Make sure you get the latest version.

Installation

Once you download the proper files, there are a couple steps you need to do:

  1. Copy the folders in reprap-arduino-firmware-x.y/library to arduino-00xx/hardware/libraries
  2. Open the GCode_Interpreter sketch in reprap-arduino-firmware-x.y/gcode/GCode_Interpreter/GCode_Interpreter.pde with the Arduino software.
  3. Configure the firmware (see below)
  4. Upload the sketch to your Arduino.

Ubuntu users will also have to upgrade their avr-gcc; the standard one contains a bug. See this link for details.

Usage

Firmware Configuration

In order for the firmware to operate properly, you must configure the proper variables in the firmware and then upload the firmware to your Arduino. The values are stored in the file _init.pde. An example version is included in the distribution called _init.pde.dist.

We'll cover each of the variables below:

X_STEPS_PER_INCH

This variable stores how many steps to take to move the X axis 1 inch. You will need to set this as accurately as possible if you want your machine to be accurate. There are two ways to set it:

  1. Move and Measure - slap a pen or marker on as a toolhead and draw a 1000 step line. Measure it and divide 1000 by the length in inches.
  2. Calculate Step Size - this one is the preferred way of doing things. Its rather easy to calculate step size based on your drive mechanism.

For threaded rod drive systems:

Find your TPI (threads per inch). for example, 1/4"-20 threaded rod means that there are 20 threads per inch (aka 20 turns = 1 inch.) Simply take that number and multiply it by the steps in a revolution. With a 400 step motor, it would be 8000 steps per inch.

For belt/pulley systems:

  1. Find the circumference of your drive pulley. (remember circumference = 2*pi*r) (say: 2.75")
  2. Calculate step size (ie: circumference / steps per revolution) (say: 2.75" / 400 = 0.00625")
  3. Divide 1 inch by step size (1" / 0.00625" = 160 steps/inch)

X_STEPS_PER_MM

This variable stores how many steps to take to move the X axis 1mm. You can either calculate it independently, or take the number above and divide by 25.4.

X_MAX_SPEED

This variable stores the maximum speed of the stepper in RPM (revolutions per minute). This is important as it determines the fastest speed to move the stepper. Start low and work your way up if you are unsure of the proper speed.

X_MOTOR_STEPS

This variable stores the number of steps per revolution. This is important as it factors into how many steps to take for a line, as well as how fast your stepper will move. Your stepper will have a fixed number of steps per revolution and should say it on the datasheet.

If you are driving your stepper in half-stepping mode, double the number of steps. Similarly, if you are using a microstepper driver, multiply the steps by the appropriate factor. Make sure you use this new step number when you are calculating steps per inch/mm.

Y_*, Z_*

These variables are the same as the variables above, but allow for different drive systems on the Y and Z axes respectively. You must still fill them out, even if all drive systems are the same.

FAST_XY_FEEDRATE and FAST_Z_FEEDRATE

These define the maximum feedrates used for the G0 command. The feedrates are given in mm/minute.

Sending Commands

The Arduino firmware waits for commands on the serial port and will start processing a command after either encountering a newline, or when there are no more characters to read.

There are several ways to control the machine through the G-Code Firmware:

  • You can either write your own custom host software to send commands,
  • Use Zach Smith's [ReplicatorG|http://replicat.org/ ReplicatorG]
  • use the RepRap host software to send commands,
  • or use the Processing app that we've bundled to send commands.

Implementation

Due to the limited size and processing power available on the Arduino, only a limited subset of G-Code has been implemented. However, the vast majority of uses of G-Code are limited to these commands. Below, we cover the implemented commands as well as limitations.

G-Codes

G0 - Rapid Motion

Implemented - only supports X, Y, and Z axes.

G1 - Coordinated Motion

Implemented - only supports X, Y, and Z axes.

G2 - Arc - Clockwise

Implemented

G3 - Arc - Counter Clockwise

Implemented

G4 - Dwell

Impemented.

G20 - Inches as units

Implemented.

G21 - Millimeters as units

Implemented.

G28 - Go Home

Implemented.

G30 - Go Home via Intermediate Point

Implemented.

G90 - Absolute Positioning

Implemented.

G91 - Incremental Positioning

Implemented.

G92 - Set current as home

Implemented. =)

M Codes

See: MCodeReference

TODO

  • Explore implementing offsets.

Bugs

  • None so far, but they are lurking.
Sours: https://reprap.org/wiki/Arduino_GCode_Interpreter
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Search Results

11 programs for "arduino gcode interpreter"

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  • 1
    Terminal-BASIC

    Terminal-BASIC is a BASIC-like language interpreter, works on a set of single board embedded systems (i.e. famous AVR uc based boards). Terminal-BASIC: * suports real numbers, multidimensional arrays and Darthmouth BASIC-style matrix operations; * written in C++11; * has modular structure (can save uc storage, instantiating only used modules); * works through different i/o devices, using vt100 commands; * on systems with multiple i/O devices can work as simple time-sharing system; * static...

  • 2
    Micrometer CNC 4 Raspberry Pi3

    ... website to verify the system image integrity upon new releases and patches. This distro will include the newest OpenSCAD, Slic3R, FreeCAD, KiCAD, pcb2gcode, k40 laser cutter tools, and ESP32 Arduino SDK. The support forums will be available for feature requests, and machine specific assistance.

  • 3

    CNCStepper

    the project was moved to: https://github.com/aiten/CNCStepper see also: https://sourceforge.net/p/cnclibrary Arduino(see download:Sketch) * Stepping Library with acceleration support * GCodeInterpreter * HPGL Interpreter sample * LCD Support * SD Support * G-Code Expression parser * Run on Arduion UNO (8bit) * Run on Arduino Mega with Ramps 1.4 * Run on Arduino Due with Ramps 1.4 (32 bit) * Run on Arduino with Ramps FD (8bit+32bit) * Stepper (HPGL Sample) on Arduino Uno * SMC 800, L298...

  • 4

    CNCLib

    CNC Interpreter for Arduino

    the project was moved to: https://github.com/aiten/CNCLib see also https://sourceforge.net/projects/cncstepper/ Windows (see download:CNCLib, use .net 4.6.1) * Sending (GCode) to Arduino * Support different machines (axis, range, ...) * Support CNC-Joystick(Arduino based) * Preview * Import HPGL with "Resize" and "Move" * Import Image (laser) * Sample for WPF, WebApi, Enterprise architecture, ... Windows (see download:Plotter) * Sending (HPGL) to Arduino sample sketch "Plotter" * Import...

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  • 5
    Easy CNC

    Easy CNC

    Modular CNC software for Arduino controller

    The goal of the project is the realization of a modular firmware that allows to control a CNC machine with different utensils. For instance, a CNC with a drill, with few changes can become a plotter with a pen or cutting machine to cut cardboard or stickers. In order to do that, we want project a CNC router with a mechanism that allows a fast utensil change and a controlling firmware which can use different utensils changing some configuration parameters.

  • 6
    Universal CNC for COM port

    Universal CNC for COM port. It's software to control CNC using arduino board(RC servo+Encoders). It has build in CAM software.

  • 7

    Arduino CNC Mill/Laser Cutter/Extruder

    This is the firmware for a CNC Mill Project I am working on. It is based on Chris Meighan's rewrite of the RepRap G-code interpreter. It is still in beta testing but it supports the following g-codes - G: 0-4,17-21,90-92 M: 3-5,30,101-108

  • 8
    Hydra: Multiheaded Manufacturing Machine

    Hydra: Multiheaded Manufacturing Machine

    Arduino firmware and Java GUI for the Hydra Multi-headed Manufacturing Machine (Hydra-MMM). The Hydra is a cartesian positioning system that has multiple, independent toolhead mounts for a wide variety of attachments. See: cpwebste.blogspot.com

  • 9

    NOTE: THIS IS LEGACY DATA AND AN OLD DESIGN KEPT AROUND FOR POSTERITY'S SAKE ONLY. FOR CURRENT DESIGN INFORMATION AND PROJECT UPDATES SEE WWW.SHAPEOKO.COM A fully open source CNC project based around the arduino microcontroller, Ponoko (the world's easiest making system), and Sparkfun. Complete drawings, and assembly documentation will be provided.

  • 10

    hbridge arduino gcode interpreter

    This is my contribution to people making cnc machines with arduino and hbridges (two pin control and bipolar steppers) I took the reprap interpreter and made my mods to use hbridges on it, because reprap firmware uses the step and dir pins...

  • 11

    HAPP

    High Accurracy and Precision Positioning

    HAPP is an acronym for High Accuracy and Precision Positioning. Basically HAPP is a light weight CNC Interpreter based on AVR, similar to grbl and marlin except this Project will support full standard gCode support including drill cycles, and other canned cycles. Another thing that brings this above other Projects is how the logic runs I have noticed several issues with other projects that both affect saftey and usability. This project is started from a person that has been in Manufacturing...

Sours: https://sourceforge.net/directory/?q=arduino%20gcode%20interpreter

G-Code Arduino Library © GPL3+

This is a library that alows any machine or robot to be controlled by G-code.

Features

  • Serial or character input
  • Customisable

What is G-Code?

G-code is the instructions that 3D printer and CNC used to create there part. G-code is a set of instruction commands sent to the controller of the machine to be performed. Position, feed rate, and tool used are some of the items that G-code can control. The G-code can either be sent from the computer or saved on an SD card.

Why make this library?

This library allows any machine or robot to be controlled by G-code. It makes it quick and easy to set up with CNC and machine software and gives much better control over the communications and commands.

Why use this?

If your project requires computer control or a set of instruction, a library like this will help simplify this process of making it your self.

Functions

SETUP

gcode(),gcode(void (*CallBack)()),gcode(int numbercommands, commandscallback *commandArray),gcode(int numbercommands, commandscallback *commandArray, void (*CallBack)());

This function is used to declare this class so that it can be used in the program. There are 4 different functions, each with variables that can be set. The callback is used to link a call back function used after each command is available. commandArray is an array of callback that interupt the program to execute the command. Numbercommands is the number of items within commandArray.

void begin(),void begin(int bitrate)

This function must be called if the serial interface is wanting to be used. Bitrate is the bitrate of the serial port. If this is called, there is no need to Serial.begin();, it is apart of the begin function.

SEND

void comment(String comment)

This function is to send comments back through the serial. Comment would be the comment that would be sent back.

RECEIVE

bool available(),bool available(char inChar)

This function reads the incoming data and returns true then the command is ready to for the program to read an control the machine. InChar is the input from a source like an SD card.

double GetValue(char commandLetter)

This function is to return the values for a command letter. CommandLetter is the command letter that is requested to be returned.

Sours: https://create.arduino.cc/projecthub/tinkersprojects/g-code-arduino-library-1a2bd6

Interpreter arduino code g

G-Code Interpreters

G-Code is the language used to describe how a machine will move to accomplish a given task, using numerical control (NC) --- it is the most widely used NC programming language. GRBL is the most frequently used implementation for the ShapeOko.

Graphical discussion of the details of converting G-code into motor commands.

Reddit: Newbie question: How is G-Code executed by the machine?

Note: some programs such as LinuxCNC directly control the machine, so are listed on the Communication / Control page.

https://github.com/NRSoft/GSharp[9] --- pre-processor which enables support for additional G-codes.

https://github.com/ithinuel/async-gcode --- A simple gcode parser written in rust

https://github.com/pantadeusz/raspigcd --- nascent firmware for Raspberry Pi[10] (limited G-Code support: G0, G1, M3, M5, M17, M18)

https://www.github.com/kobaltz/rotor --- Ruby gem called Rotor that interprets GCode and will control stepper motors[11]

https://github.com/MarginallyClever/GcodeCNCDemo/tree/master/GcodeCNCDemo2Axis --- source code for a simple g-code interpreter. The interpreter reads the g-code commands line by line from the serial port, interprets them, and then executes them. To execute e.g. a move 10mm command in the X-axis, the interpreter steps the X axis motor the appropriate number of steps.[12]

There are a number of firmware options for 3D printers, some of which are also suited for use in controlling a more general-purpose CNC machine: 3D Printing: G-Code Intpreters.

List from: http://www.sawmillcreek.org/showthread.php?237402-Probotix-CNC-Nebula-Question&p=2489851#post2489851

See also Netduino CNC.

http://gofabmo.org/

https://www.synthetos.com/what-is-tinyg-and-why/

https://groups.yahoo.com/neo/groups/CNCPro/info --- old DOS program recently opensourced

https://www.jedicut.com/en/ --- hot wire cutting controller capable of 4-axis movement

http://www.micrometer.xyz/cdn/

Sours: https://wiki.shapeoko.com/index.php/G-Code_Interpreters
How to send g-code in ardiuno

How to build an 2-axis Arduino CNC Gcode Interpreter

Computer model of where the 3-axis CNC router will move to cut the shape

Purpose

3D printers, laser cutters, water jet cutters, robot arms, delta robots, stewart platforms, the Makelangelo: all of these are examples of computer numerical control (CNC) machines. CNC machines need to move accurately and on command. Stepper motors are a great way to move accurately – they move a predictable amount and then stay where you put them. To command the stepper motors we need a way to easily turn our human desires into machine instructions into stepper motor steps. In effect we need our robot brain to be an interpreter. I’m going to show you a simple interpreter written for Arduino that lets you move stepper motors for your robots.

Audience

This tutorial is meant for people who have an Arduino and understand the basics of programming in C. That means variables, methods, while(), if(), switch(), and manipulating strings. There’s even a few ?: style if statements.

Interpreters

In the very beginnings of computers the programmers talked to the machines in machine languages – the ones and zeros of binary. They memorized the binary machine language and wrote programs in that machine language. Each program probably did one small job because they were so hard to write.

Then somebody got smart and wrote the first interpreter – a binary program that could turn a more human language (assembly) into binary. Every language since then has been a different flavor of the same ice cream: trying to find easier ways of letting humans tell machines what to do. Most programs today are written using interpreters that were built using interpreters that were built using the original interpreters. Ours will be, too. So Meta!

Goal

I can’t build something without a clearly defined goal. I need to see the target in order to hit it.

I could write a 10-line program that does one pattern of motor movements but then – just like the binary programmers of yore – I would have to write a new program for every pattern. Compiling, uploading, and testing a program is a time-consuming process. My goal is to write an interpreter that can listen and respond in real time to any pattern.

Before you can run an Arduino program you have to compile and upload it. When our program is done you won’t have to compile anything. You will send the gcode to the Arduino through the serial connection and the Arduino will listen, understand, and obey.

Hardware

My NEMA 17 stepper motors are controlled by an L293 motor shield riding on top of an Arduino UNO. On the motor shield I attached a female power plug so I could easily plug in a 12v power supply. I put a piece of tape on the motor shaft of each stepper so I can easily see it moving. Later I can replace that with pulleys and belts.

[products skus=”MOTO-0003,ELEC-0007,KIT-0002,ELEC-0004″]

For the sake of simplicity I’m going to assume that our motors are moving orthogonal to each other. That means on a grid that one motor moves along the X axis and one moves on the Y axis, also known as a cartesian coordinate system. (Delta robots, stewart platforms, and robot arms all use much more complicated systems to arrive at the same effect.)

Because we’re moving in a grid I can use Bresenham’s Line Algorithm to move each motor at same time with different relative speeds. That means in our cartesian system I can draw lines from anywhere to anywhere and they’ll be nice and straight. I can draw curves by chopping the curve into lots of tiny lines that approximate the curve shape.

Method

The Arduino will need to:

  • Setup:
    • start listening to the serial connection
    • set up the stepper motors
    • Tell whoever is listening that we’re ready for more instructions.
  • Loop forever:
    • Wait for a message
    • Read the message
    • Interpret the meaning
    • Act on that meaning
    • Tell whoever is listening that we’re ready for more instructions.

Gcode

The messages I send to the Arduino could be in any language. I could even make up a language! To keep life simple I’m going to use a language other people know and understand, called gcode.

The rules of gcode – the punctuation, syntax, grammar, and vocabulary – are very easy to explain to a machine. Gcode commands all consist of an uppercase letter followed by a number. Here are the codes I’m going to build into the interpreter.

CommandMeaning
G00 [X(number)] [Y(number)] [F(number)]
G01 [X(number)] [Y(number)] [F(number)]
Absolute mode: Move in a line to (X,Y) at speed F
Relative Mode: Move (X,Y) amount at speed F
G04 P(number)Do nothing for P seconds
G90absolute mode
G91relative mode
G92 [X(number)] [Y(number)]change logical position
M18turn off power to motors
M100print out instructions for the human
M114report position and feedrate
  • Every (number) is assumed to be a float – a number that might have a decimal place and an exponent. 2.015e-5 is a float.
  • Anything in [brackets] is optional.
  • G and M commands cannot be combined in a single instruction.
  • Arduino software has a nice way to send messages to the PCB through the serial interface window. It’s the magnifying glass on the right hand side of the Arduino window. Unfortunately the serial interface window doesn’t send the return key (\n) to the PCB. Instead of return I’m going to use semicolon (;) to tell the machine “this is the end of an instruction”.

Setup

#define BAUD (57600) // How fast is the Arduino talking? #define MAX_BUF (64) // What is the longest message Arduino can store? char buffer[MAX_BUF]; // where we store the message until we get a ';' int sofar; // how much is in the buffer /** * First thing this machine does on startup. Runs only once. */ void setup() { Serial.begin(BAUD); // open coms help(); // say hello set_feedrate(200); // set default speed ready(); } /** * display helpful information */ void help() { Serial.print(F("CNC Robot ")); Serial.println(VERSION); Serial.println(F("Commands:")); Serial.println(F("G00 [X(steps)] [Y(steps)] [F(feedrate)]; - linear move")); Serial.println(F("G01 [X(steps)] [Y(steps)] [F(feedrate)]; - linear move")); Serial.println(F("G04 P[seconds]; - delay")); Serial.println(F("G90; - absolute mode")); Serial.println(F("G91; - relative mode")); Serial.println(F("G92 [X(steps)] [Y(steps)]; - change logical position")); Serial.println(F("M18; - disable motors")); Serial.println(F("M100; - this help message")); Serial.println(F("M114; - report position and feedrate")); } /** * prepares the input buffer to receive a new message and * tells the serial connected device it is ready for more. */ void ready() { sofar=0; // clear input buffer Serial.print(F("> ")); // signal ready to receive input }

The only mystery here should be , a special Arduino-only macro. It tells the compiler to put the string in program memory instead of RAM, which can sometimes be the difference between a program that fits on an Arduino and a program that doesn’t.

Loop

/** * After setup() this machine will repeat loop() forever. */ void loop() { // listen for commands if( Serial.available() ) { // if something is available char c = Serial.read(); // get it Serial.print(c); // optional: repeat back what I got for debugging // store the byte as long as there's room in the buffer. // if the buffer is full some data might get lost if(sofar < MAX_BUF) buffer[sofar++]=c; // if we got a return character (\n) the message is done. if(c=='\n') { Serial.print(F("\r\n")); // optional: send back a return for debugging // strings must end with a \0. buffer[sofar]=0; processCommand(); // do something with the command ready(); } } }

I tend to write my comments first, then I write the code between the comments. That way I get my ideas organized and the code is better documented when I’m done.

Interpreting Commands and Responding

/** * Read the input buffer and find any recognized commands. One G or M command per line. */ void processCommand() { // look for commands that start with 'G' int cmd=parsenumber('G',-1); switch(cmd) { case 0: // move in a line case 1: // move in a line set_feedrate(parsenumber('F',fr)); line( parsenumber('X',(mode_abs?px:0)) + (mode_abs?0:px), parsenumber('Y',(mode_abs?py:0)) + (mode_abs?0:py) ); break; // case 2: // clockwise arc // case 3: // counter-clockwise arc case 4: pause(parsenumber('P',0)*1000); break; // wait a while case 90: mode_abs=1; break; // absolute mode case 91: mode_abs=0; break; // relative mode case 92: // set logical position position( parsenumber('X',0), parsenumber('Y',0) ); break; default: break; } // look for commands that start with 'M' cmd=parsenumber('M',-1); switch(cmd) { case 18: // turns off power to steppers (releases the grip) m1.release(); m2.release(); break; case 100: help(); break; case 114: where(); break; // prints px, py, fr, and mode. default: break; } // if the string has no G or M commands it will get here and the Arduino will silently ignore it }

searches for the letter ‘key’ in buffer. If it finds key it return the number that follows immediately after. If it doesn’t find key it returns ‘default’.

Drawing lines

I first learned about Bresenham’s line algorithm from André LaMothe in one of his books back in the early 90’s. I think it was “The Black Art of 3D Game Programming”? It’s supposed to be used for drawing graphics on a computer screen. It works just as well for our purposes, and it can be extended to any number of motors all moving at once.

The slope of a line can be expressed as dx/dy. Let’s pretend for a moment that dx/dy is 1/3. Three steps on Y equals one step on X. Bresenham’s algorithm starts stepping along Y and adds dx to a counter. when the counter >= Y, step once on X. Here’s the best part: by using the slope of the entire line we can do all the math with whole numbers, which means we shouldn’t get any rounding errors and our Arduino can do the math extra fast. Whole number math nearly always faster than floating point math.

/** * Uses Bresenham's line algorithm to move both motors * @input newx the destination x position * @input newy the destination y position **/ void line(float newx,float newy) { long dx=newx-px; // distance to move (delta) long dy=newy-py; int dirx=dx > 0?1:-1; // direction to move int diry=dy > 0?1:-1; dx=abs(dx); // absolute delta dy=abs(dy); long i; long over=0; if(dx > dy) { for(i=0;i < dx;++i) { m1.onestep(dirx); over+=dy; if(over>=dx) { over-=dx; m2.onestep(diry); } pause(step_delay); // step_delay is a global connected to feed rate. // test limits and/or e-stop here } } else { for(i=0;i < dy;++i) { m2.onestep(diry); over+=dx; if(over>=dy) { over-=dy; m1.onestep(dirx); } pause(step_delay); // step_delay is a global connected to feed rate. // test limits and/or e-stop here } } // update the logical position. We don't just = newx because // px + dx * dirx == newx could be false by a tiny margin and we don't want rounding errors. px+= dx*dirx; py+= dy*diry; } /** * delay for the appropriate number of microseconds * @input ms how many milliseconds to wait */ void pause(long ms) { delay(ms/1000); delayMicroseconds(ms%1000); // delayMicroseconds doesn't work for values > ~16k. } /** * Set the feedrate (speed motors will move) * @input nfr the new speed in steps/second */ void set_feedrate(float nfr) { if(fr==nfr) return; // same as last time? quit now. if(nfr > MAX_FEEDRATE || nfr < MIN_FEEDRATE) { // don't allow crazy feed rates Serial.print(F("New feedrate must be greater than ")); Serial.print(MIN_FEEDRATE); Serial.print(F("steps/s and less than ")); Serial.print(MAX_FEEDRATE); Serial.println(F("steps/s.")); return; } step_delay = 1000000.0/nfr; fr=nfr; }

Source

Want the entire source in one file, ready to compile? Here you go. I use a version of this code in nearly all Marginally Clever robots.

Edit 2014-09-29: I’ve since added examples for Adafruit Motor Shield v1, Adafruit Motor Shield v2, RUMBA, and RAMPs.

Video!

This is an updated version that drives 4 steppers at once. It could be done with even more.

Now you try

  • Add a for line numbers. Then your machine can detect if it receives lines in the wrong order, or request specific lines from the computer. You may also need to understand M110 N[number] so the computer can set the line number.
  • Add a ‘;’ on the end of every command, followed by a checksum. Then the arduino can tell if the message is correctly received.
  • Add G02 and G03 for curved lines.

Final thoughts

So there you have it. In 293 lines of code we’ve built a really simple CNC machine Gcode interpreter that handles six G commands and three M commands.

If you’d like me to go into more detail about how to make arcs, or something else then please make a comment below and I’ll post about it.

Please share videos & pictures of your creations to the forums.

See Also

How to choose your controller electronics to build your first CNC.

Sours: https://www.marginallyclever.com/2013/08/how-to-build-an-2-axis-arduino-cnc-gcode-interpreter/

Now discussing:

Read G-Code and execute it on Arduino

1)I am using Arduino UNO.
2)3 Step motors for 3 axis.

The code that i have used was :

#define BAUD (57600) // How fast is the Arduino talking?
#define MAX_BUF (64) // What is the longest message Arduino can store?

char buffer[MAX_BUF]; // where we store the message until we get a ‘;’
int sofar; // how much is in the buffer

/**

  • First thing this machine does on startup. Runs only once.
    */
    void setup() {
    Serial.begin(BAUD); // open coms
    help(); // say hello
    set_feedrate(200); // set default speed
    ready();
    }

/**

  • display helpful information
    */
    void help() {
    Serial.print(F("CNC Robot "));
    Serial.println(VERSION);
    Serial.println(F(“Commands:”));
    Serial.println(F(“G00 [X(steps)] [Y(steps)] [F(feedrate)]; - linear move”));
    Serial.println(F(“G01 [X(steps)] [Y(steps)] [F(feedrate)]; - linear move”));
    Serial.println(F(“G04 P[seconds]; - delay”));
    Serial.println(F(“G90; - absolute mode”));
    Serial.println(F(“G91; - relative mode”));
    Serial.println(F(“G92 [X(steps)] [Y(steps)]; - change logical position”));
    Serial.println(F(“M18; - disable motors”));
    Serial.println(F(“M100; - this help message”));
    Serial.println(F(“M114; - report position and feedrate”));
    }

/**

  • prepares the input buffer to receive a new message and
  • tells the serial connected device it is ready for more.
    /
    void ready() {
    sofar=0; // clear input buffer
    Serial.print(F("> ")); // signal ready to receive input
    }
    /
    *
  • After setup() this machine will repeat loop() forever.
    */
    void loop() {
    // listen for commands
    if( Serial.available() ) { // if something is available
    char c = Serial.read(); // get it
    Serial.print(c); // optional: repeat back what I got for debugging

// store the byte as long as there’s room in the buffer.
// if the buffer is full some data might get lost
if(sofar < MAX_BUF) buffer[sofar++]=c;
// if we got a return character (\n) the message is done.
if(c==’\n’) {
Serial.print(F("\r\n")); // optional: send back a return for debugging

// strings must end with a \0.
buffer[sofar]=0;
processCommand(); // do something with the command
ready();
}
}
}
/**

  • Read the input buffer and find any recognized commands. One G or M command per line.
    */
    void processCommand() {
    // look for commands that start with ‘G’
    int cmd=parsenumber(‘G’,-1);
    switch(cmd) {
    case 0: // move in a line
    case 1: // move in a line
    set_feedrate(parsenumber(‘F’,fr));
    line( parsenumber(‘X’,(mode_abs?px:0)) + (mode_abs?0:px),
    parsenumber(‘Y’,(mode_abs?py:0)) + (mode_abs?0:py) );
    break;
    // case 2: // clockwise arc
    // case 3: // counter-clockwise arc
    case 4: pause(parsenumber(‘P’,0)*1000); break; // wait a while
    case 90: mode_abs=1; break; // absolute mode
    case 91: mode_abs=0; break; // relative mode
    case 92: // set logical position
    position( parsenumber(‘X’,0),
    parsenumber(‘Y’,0) );
    break;
    default: break;
    }

// look for commands that start with ‘M’
cmd=parsenumber(‘M’,-1);
switch(cmd) {
case 18: // turns off power to steppers (releases the grip)
m1.release();
m2.release();
break;
case 100: help(); break;
case 114: where(); break; // prints px, py, fr, and mode.
default: break;
}

// if the string has no G or M commands it will get here and the Arduino will silently ignore it
}
parsenumber(key,default)
/**

  • Uses Bresenham’s line algorithm to move both motors
  • @input newx the destination x position
  • @input newy the destination y position
    **/
    void line(float newx,float newy) {
    long dx=newx-px; // distance to move (delta)
    long dy=newy-py;
    int dirx=dx > 0?1:-1; // direction to move
    int diry=dy > 0?1:-1;
    dx=abs(dx); // absolute delta
    dy=abs(dy);

long i;
long over=0;

if(dx > dy) {
for(i=0;i < dx;++i) {
m1.onestep(dirx);
over+=dy;
if(over>=dx) {
over-=dx;
m2.onestep(diry);
}
pause(step_delay); // step_delay is a global connected to feed rate.
// test limits and/or e-stop here
}
} else {
for(i=0;i < dy;++i) { m2.onestep(diry); over+=dx; if(over>=dy) { over-=dy; m1.onestep(dirx); } pause(step_delay); // step_delay is a global connected to feed rate. // test limits and/or e-stop here } } // update the logical position. We don’t just = newx because // px + dx * dirx == newx could be false by a tiny margin and we don’t want rounding errors. px+= dxdirx; py+= dydiry; } /** * delay for the appropriate number of microseconds * @input ms how many milliseconds to wait / void pause(long ms) { delay(ms/1000); delayMicroseconds(ms%1000); // delayMicroseconds doesn’t work for values > ~16k. } /* * Set the feedrate (speed motors will move) * @input nfr the new speed in steps/second */ void set_feedrate(float nfr) { if(fr==nfr) return; // same as last time? quit now. if(nfr > MAX_FEEDRATE || nfr < MIN_FEEDRATE) { // don’t allow crazy feed rates
Serial.print(F("New feedrate must be greater than "));
Serial.print(MIN_FEEDRATE);
Serial.print(F("steps/s and less than "));
Serial.print(MAX_FEEDRATE);
Serial.println(F(“steps/s.”));
return;
}
step_delay = 1000000.0/nfr;
fr=nfr;
}

Which corrections would be helpful.Thank you.

Sours: https://forum.arduino.cc/t/read-g-code-and-execute-it-on-arduino/525626


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