Mrinnovative
Published © GPL3+

Arduino Based Mini CNC 2D Plotter

A mini CNC 2D plotter made from old DVD drive and L293D motor shield. Very cheap but interesting. It can draw any image uploaded from PC.

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Arduino Based Mini CNC 2D Plotter

Things used in this project

Story

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Schematics

Complete wiring drawing

Wiring drawing for Motor shield to stepper

Code

CNC code foR Arduino

C/C++
Upload this code to Arduino board
/* 
 https://www.youtube.com/watch?v=opZ9RgmOIpc
  */

#include <Servo.h>
#include <AFMotor.h>

#define LINE_BUFFER_LENGTH 512

char STEP = MICROSTEP ;

// Servo position for Up and Down 
const int penZUp = 115;
const int penZDown = 83;

// Servo on PWM pin 10
const int penServoPin =10 ;

// Should be right for DVD steppers, but is not too important here
const int stepsPerRevolution = 48; 

// create servo object to control a servo 
Servo penServo;  

// Initialize steppers for X- and Y-axis using this Arduino pins for the L293D H-bridge
AF_Stepper myStepperY(stepsPerRevolution,1);            
AF_Stepper myStepperX(stepsPerRevolution,2);  

/* Structures, global variables    */
struct point { 
  float x; 
  float y; 
  float z; 
};

// Current position of plothead
struct point actuatorPos;

//  Drawing settings, should be OK
float StepInc = 1;
int StepDelay = 0;
int LineDelay =0;
int penDelay = 50;

// Motor steps to go 1 millimeter.
// Use test sketch to go 100 steps. Measure the length of line. 
// Calculate steps per mm. Enter here.
float StepsPerMillimeterX = 100.0;
float StepsPerMillimeterY = 100.0;

// Drawing robot limits, in mm
// OK to start with. Could go up to 50 mm if calibrated well. 
float Xmin = 0;
float Xmax = 40;
float Ymin = 0;
float Ymax = 40;
float Zmin = 0;
float Zmax = 1;

float Xpos = Xmin;
float Ypos = Ymin;
float Zpos = Zmax; 

// Set to true to get debug output.
boolean verbose = false;

//  Needs to interpret 
//  G1 for moving
//  G4 P300 (wait 150ms)
//  M300 S30 (pen down)
//  M300 S50 (pen up)
//  Discard anything with a (
//  Discard any other command!

/**********************
 * void setup() - Initialisations
 ***********************/
void setup() {
  //  Setup
  
  Serial.begin( 9600 );
  
  penServo.attach(penServoPin);
  penServo.write(penZUp);
  delay(100);

  // Decrease if necessary
  myStepperX.setSpeed(600);

  myStepperY.setSpeed(600);  
  

  //  Set & move to initial default position
  // TBD

  //  Notifications!!!
  Serial.println("Mini CNC Plotter alive and kicking!");
  Serial.print("X range is from "); 
  Serial.print(Xmin); 
  Serial.print(" to "); 
  Serial.print(Xmax); 
  Serial.println(" mm."); 
  Serial.print("Y range is from "); 
  Serial.print(Ymin); 
  Serial.print(" to "); 
  Serial.print(Ymax); 
  Serial.println(" mm."); 
}

/**********************
 * void loop() - Main loop
 ***********************/
void loop() 
{
  
  delay(100);
  char line[ LINE_BUFFER_LENGTH ];
  char c;
  int lineIndex;
  bool lineIsComment, lineSemiColon;

  lineIndex = 0;
  lineSemiColon = false;
  lineIsComment = false;

  while (1) {

    // Serial reception - Mostly from Grbl, added semicolon support
    while ( Serial.available()>0 ) {
      c = Serial.read();
      if (( c == '\n') || (c == '\r') ) {             // End of line reached
        if ( lineIndex > 0 ) {                        // Line is complete. Then execute!
          line[ lineIndex ] = '\0';                   // Terminate string
          if (verbose) { 
            Serial.print( "Received : "); 
            Serial.println( line ); 
          }
          processIncomingLine( line, lineIndex );
          lineIndex = 0;
        } 
        else { 
          // Empty or comment line. Skip block.
        }
        lineIsComment = false;
        lineSemiColon = false;
        Serial.println("ok");    
      } 
      else {
        if ( (lineIsComment) || (lineSemiColon) ) {   // Throw away all comment characters
          if ( c == ')' )  lineIsComment = false;     // End of comment. Resume line.
        } 
        else {
          if ( c <= ' ' ) {                           // Throw away whitepace and control characters
          } 
          else if ( c == '/' ) {                    // Block delete not supported. Ignore character.
          } 
          else if ( c == '(' ) {                    // Enable comments flag and ignore all characters until ')' or EOL.
            lineIsComment = true;
          } 
          else if ( c == ';' ) {
            lineSemiColon = true;
          } 
          else if ( lineIndex >= LINE_BUFFER_LENGTH-1 ) {
            Serial.println( "ERROR - lineBuffer overflow" );
            lineIsComment = false;
            lineSemiColon = false;
          } 
          else if ( c >= 'a' && c <= 'z' ) {        // Upcase lowercase
            line[ lineIndex++ ] = c-'a'+'A';
          } 
          else {
            line[ lineIndex++ ] = c;
          }
        }
      }
    }
  }
}

void processIncomingLine( char* line, int charNB ) {
  int currentIndex = 0;
  char buffer[ 64 ];                                 // Hope that 64 is enough for 1 parameter
  struct point newPos;

  newPos.x = 0.0;
  newPos.y = 0.0;

  //  Needs to interpret 
  //  G1 for moving
  //  G4 P300 (wait 150ms)
  //  G1 X60 Y30
  //  G1 X30 Y50
  //  M300 S30 (pen down)
  //  M300 S50 (pen up)
  //  Discard anything with a (
  //  Discard any other command!

  while( currentIndex < charNB ) {
    switch ( line[ currentIndex++ ] ) {              // Select command, if any
    case 'U':
      penUp(); 
      break;
    case 'D':
      penDown(); 
      break;
    case 'G':
      buffer[0] = line[ currentIndex++ ];          // /!\ Dirty - Only works with 2 digit commands
      //      buffer[1] = line[ currentIndex++ ];
      //      buffer[2] = '\0';
      buffer[1] = '\0';

      switch ( atoi( buffer ) ){                   // Select G command
      case 0:                                   // G00 & G01 - Movement or fast movement. Same here
      case 1:
        // /!\ Dirty - Suppose that X is before Y
        char* indexX = strchr( line+currentIndex, 'X' );  // Get X/Y position in the string (if any)
        char* indexY = strchr( line+currentIndex, 'Y' );
        if ( indexY <= 0 ) {
          newPos.x = atof( indexX + 1); 
          newPos.y = actuatorPos.y;
        } 
        else if ( indexX <= 0 ) {
          newPos.y = atof( indexY + 1);
          newPos.x = actuatorPos.x;
        } 
        else {
          newPos.y = atof( indexY + 1);
          indexY = '\0';
          newPos.x = atof( indexX + 1);
        }
        drawLine(newPos.x, newPos.y );
        //        Serial.println("ok");
        actuatorPos.x = newPos.x;
        actuatorPos.y = newPos.y;
        break;
      }
      break;
    case 'M':
      buffer[0] = line[ currentIndex++ ];        // /!\ Dirty - Only works with 3 digit commands
      buffer[1] = line[ currentIndex++ ];
      buffer[2] = line[ currentIndex++ ];
      buffer[3] = '\0';
      switch ( atoi( buffer ) ){
      case 300:
        {
          char* indexS = strchr( line+currentIndex, 'S' );
          float Spos = atof( indexS + 1);
          //         Serial.println("ok");
          if (Spos == 30) { 
            penDown(); 
          }
          if (Spos == 50) { 
            penUp(); 
          }
          break;
        }
      case 114:                                // M114 - Repport position
        Serial.print( "Absolute position : X = " );
        Serial.print( actuatorPos.x );
        Serial.print( "  -  Y = " );
        Serial.println( actuatorPos.y );
        break;
      default:
        Serial.print( "Command not recognized : M");
        Serial.println( buffer );
      }
    }
  }



}


/*********************************
 * Draw a line from (x0;y0) to (x1;y1).
 * int (x1;y1) : Starting coordinates
 * int (x2;y2) : Ending coordinates
 **********************************/
void drawLine(float x1, float y1) {

  if (verbose)
  {
    Serial.print("fx1, fy1: ");
    Serial.print(x1);
    Serial.print(",");
    Serial.print(y1);
    Serial.println("");
  }  

  //  Bring instructions within limits
  if (x1 >= Xmax) { 
    x1 = Xmax; 
  }
  if (x1 <= Xmin) { 
    x1 = Xmin; 
  }
  if (y1 >= Ymax) { 
    y1 = Ymax; 
  }
  if (y1 <= Ymin) { 
    y1 = Ymin; 
  }

  if (verbose)
  {
    Serial.print("Xpos, Ypos: ");
    Serial.print(Xpos);
    Serial.print(",");
    Serial.print(Ypos);
    Serial.println("");
  }

  if (verbose)
  {
    Serial.print("x1, y1: ");
    Serial.print(x1);
    Serial.print(",");
    Serial.print(y1);
    Serial.println("");
  }

  //  Convert coordinates to steps
  x1 = (int)(x1*StepsPerMillimeterX);
  y1 = (int)(y1*StepsPerMillimeterY);
  float x0 = Xpos;
  float y0 = Ypos;

  //  Let's find out the change for the coordinates
  long dx = abs(x1-x0);
  long dy = abs(y1-y0);
  int sx = x0<x1 ? StepInc : -StepInc;
  int sy = y0<y1 ? StepInc : -StepInc;

  long i;
  long over = 0;

  if (dx > dy) {
    for (i=0; i<dx; ++i) {
      myStepperX.onestep(sx,STEP);
      over+=dy;
      if (over>=dx) {
        over-=dx;
        myStepperY.onestep(sy,STEP);
      }
    delay(StepDelay);
    }
  }
  else {
    for (i=0; i<dy; ++i) {
      myStepperY.onestep(sy,STEP);
      over+=dx;
      if (over>=dy) {
        over-=dy;
        myStepperX.onestep(sx,STEP);
      }
      delay(StepDelay);
    }    
  }

  if (verbose)
  {
    Serial.print("dx, dy:");
    Serial.print(dx);
    Serial.print(",");
    Serial.print(dy);
    Serial.println("");
  }

  if (verbose)
  {
    Serial.print("Going to (");
    Serial.print(x0);
    Serial.print(",");
    Serial.print(y0);
    Serial.println(")");
  }

  //  Delay before any next lines are submitted
  delay(LineDelay);
  //  Update the positions
  Xpos = x1;
  Ypos = y1;
}

//  Raises pen
void penUp() { 
  penServo.write(penZUp); 
  delay(penDelay); 
  Zpos=Zmax; 
  digitalWrite(15, LOW);
    digitalWrite(16, HIGH);
  if (verbose) { 
    Serial.println("Pen up!"); 
    
  } 
}
//  Lowers pen
void penDown() { 
  penServo.write(penZDown); 
  delay(penDelay); 
  Zpos=Zmin; 
  digitalWrite(15, HIGH);
    digitalWrite(16, LOW);
  if (verbose) { 
    Serial.println("Pen down."); 
    
    
  } 
}

GCTRL

Java
Run this code in Processing IDE
import java.awt.event.KeyEvent;
import javax.swing.JOptionPane;
import processing.serial.*;

Serial port = null;

// select and modify the appropriate line for your operating system
// leave as null to use interactive port (press 'p' in the program)
String portname = null;
//String portname = Serial.list()[0]; // Mac OS X
//String portname = "/dev/ttyUSB0"; // Linux
//String portname = "COM6"; // Windows

boolean streaming = false;
float speed = 0.001;
String[] gcode;
int i = 0;

void openSerialPort()
{
  if (portname == null) return;
  if (port != null) port.stop();
  
  port = new Serial(this, portname, 9600);
  
  port.bufferUntil('\n');
}

void selectSerialPort()
{
  String result = (String) JOptionPane.showInputDialog(this,
    "Select the serial port that corresponds to your Arduino board.",
    "Select serial port",
    JOptionPane.PLAIN_MESSAGE,
    null,
    Serial.list(),
    0);
    
  if (result != null) {
    portname = result;
    openSerialPort();
  }
}

void setup()
{
  size(500, 250);
  openSerialPort();
}

void draw()
{
  background(0);  
  fill(255);
  int y = 24, dy = 12;
  text("INSTRUCTIONS", 12, y); y += dy;
  text("p: select serial port", 12, y); y += dy;
  text("1: set speed to 0.001 inches (1 mil) per jog", 12, y); y += dy;
  text("2: set speed to 0.010 inches (10 mil) per jog", 12, y); y += dy;
  text("3: set speed to 0.100 inches (100 mil) per jog", 12, y); y += dy;
  text("arrow keys: jog in x-y plane", 12, y); y += dy;
  text("page up & page down: jog in z axis", 12, y); y += dy;
  text("$: display grbl settings", 12, y); y+= dy;
  text("h: go home", 12, y); y += dy;
  text("0: zero machine (set home to the current location)", 12, y); y += dy;
  text("g: stream a g-code file", 12, y); y += dy;
  text("x: stop streaming g-code (this is NOT immediate)", 12, y); y += dy;
  y = height - dy;
  text("current jog speed: " + speed + " inches per step", 12, y); y -= dy;
  text("current serial port: " + portname, 12, y); y -= dy;
}

void keyPressed()
{
  if (key == '1') speed = 0.001;
  if (key == '2') speed = 0.01;
  if (key == '3') speed = 0.1;
  
  if (!streaming) {
    if (keyCode == LEFT) port.write("G91\nG20\nG00 X-" + speed + " Y0.000 Z0.000\n");
    if (keyCode == RIGHT) port.write("G91\nG20\nG00 X" + speed + " Y0.000 Z0.000\n");
    if (keyCode == UP) port.write("G91\nG20\nG00 X0.000 Y" + speed + " Z0.000\n");
    if (keyCode == DOWN) port.write("G91\nG20\nG00 X0.000 Y-" + speed + " Z0.000\n");
    if (keyCode == KeyEvent.VK_PAGE_UP) port.write("G91\nG20\nG00 X0.000 Y0.000 Z" + speed + "\n");
    if (keyCode == KeyEvent.VK_PAGE_DOWN) port.write("G91\nG20\nG00 X0.000 Y0.000 Z-" + speed + "\n");
    if (key == 'h') port.write("G90\nG20\nG00 X0.000 Y0.000 Z0.000\n");
    if (key == 'v') port.write("$0=75\n$1=74\n$2=75\n");
    //if (key == 'v') port.write("$0=100\n$1=74\n$2=75\n");
    if (key == 's') port.write("$3=10\n");
    if (key == 'e') port.write("$16=1\n");
    if (key == 'd') port.write("$16=0\n");
    if (key == '0') openSerialPort();
    if (key == 'p') selectSerialPort();
    if (key == '$') port.write("$$\n");
  }
  
  if (!streaming && key == 'g') {
    gcode = null; i = 0;
    File file = null; 
    println("Loading file...");
    selectInput("Select a file to process:", "fileSelected", file);
  }
  
  if (key == 'x') streaming = false;
}

void fileSelected(File selection) {
  if (selection == null) {
    println("Window was closed or the user hit cancel.");
  } else {
    println("User selected " + selection.getAbsolutePath());
    gcode = loadStrings(selection.getAbsolutePath());
    if (gcode == null) return;
    streaming = true;
    stream();
  }
}

void stream()
{
  if (!streaming) return;
  
  while (true) {
    if (i == gcode.length) {
      streaming = false;
      return;
    }
    
    if (gcode[i].trim().length() == 0) i++;
    else break;
  }
  
  println(gcode[i]);
  port.write(gcode[i] + '\n');
  i++;
}

void serialEvent(Serial p)
{
  String s = p.readStringUntil('\n');
  println(s.trim());
  
  if (s.trim().startsWith("ok")) stream();
  if (s.trim().startsWith("error")) stream(); // XXX: really?
}

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Mrinnovative

Mrinnovative

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