#include 

#define reprap 6
#define slave 5

void setup ()
 {
 Wire.begin (reprap);
 }
 
void loop()
{
  Wire.beginTransmission (slave);
  Wire.send ("G1"); 
  Wire.endTransmission();
  
  Wire.beginTransmission (slave);
  Wire.send ("G28");
  Wire.endTransmission();
}

#include 

#define slave 5
#define LED 13

void receiveEvent (int howMany)
 {
  char buf [10];
  byte i = 0;

  while (Wire.available () > 0)
    {
    char c = Wire.receive ();
    if (i < sizeof (buf) - 1)  // check for overflow
      buf [i++] = c;
    }  // end of while

   buf  = 0;  // terminating null
   
  if (memcmp (buf, "G1", 2) == 0)
    digitalWrite (LED, HIGH);
  else if (memcmp (buf, "G28", 3) == 0)
    digitalWrite (LED, LOW);
}  // end of receiveEvent


void setup () 
{
  Wire.begin (slave);
  Wire.onReceive (receiveEvent);
  pinMode (LED, OUTPUT);
}  // end of setup

void loop() 
{
// nothing in main loop
}

                       case 100: 
                               Wire.beginTransmission (5);
                               Wire.send ("G100"); 
                               Wire.endTransmission();
				break;

                        case 101: 
                               Wire.beginTransmission (5);
                               Wire.send ("G101"); 
                               Wire.endTransmission();
				break;

void receiveEvent(int howMany)
{

}

void requestEvent()
{
  Wire.send("start");
}

//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;
void setup()
{  
  Wire.begin(4);
}
void loop()
{
 
}

#include "Wire.h"

//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;
int ledPin = 2;

void setup()
{
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial 
  pinMode(ledPin, OUTPUT);  
}

void receiveEvent(int howMany)
{
  char incoming[128]; // Set this to the maximum expected string length +1 for a null char 
  char length;
  while(0 < Wire.available()) // loop through all
   {
     delay(100); 
    length = Wire.available();
    for (int i = 0; i < length; i++) {
        if(i > 128){                       //prevent data corruption in case you accidentally receive more than the array can hold
            incoming[128] = '\0';  //put a null char at the end of the array
            break;
        } 
        incoming = Wire.receive();
        }
    }
    char str1[] = "G100";
 char str2[] = "G101"; 
  
  if (strcmp(str1, incoming) == 0){
      //turn dispenser on
      digitalWrite(2, HIGH); }
    
    if (strcmp(str2, incoming) == 0) {    
      //turn dispenser off
      digitalWrite(2, LOW);}
}

#include "Wire.h"

//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;
int ledPin = 2;                 // LED connected to digital pin 2

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial
//Test gcode, this should send the machine's X, Y and Z to home
  sendGCode("G28 X0 Y0 Z0\n");
}

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    if (c = '1') 
    {
      //turn dispenser on
      digitalWrite(2, HIGH); //replace the number 2 with the dispenser pin number
    }
    if (c = '0') 
    {
      //turn dispenser off
      digitalWrite(2, LOW);
    }
  }
}

void sendGCode(char* GCode)
{
  Wire.beginTransmission(REP_RAP_ADDR);
  Wire.send(GCode);
  Wire.endTransmission();   
}

void loop()
{
  
}

if (e_can_step)
		{
			dda_counter.e += delta_steps.e;
			
			if (dda_counter.e > 0)
			{
                                
				do_e_step();
                                real_move = true;
				dda_counter.e -= total_steps;
				
				if (e_direction)
					current_steps.e++;
				else
					current_steps.e--;
			}
		}

// Default to the origin and not going anywhere
  
	target_position.x = 0.0;
	target_position.y = 0.0;
	target_position.z = 0.0;
	target_position.e = 0.0;
        target_position.f = SLOW_XY_FEEDRATE;

[ww1.microchip.com]

Quote

Another option (although probably not the best for this application it would still be an effective and viable solution) is to develop a small protocol to give the gen 6 direct access to the arduino's pins (it's simpler than it sounds), each byte sent via i2c could contain a pin number in the lowest 4 bits, its state in the fifth and its mode in the sixth and then perhaps for efficiency the seventh bit could be to determine if the pin mode needs changing, that leaves one bit spare if you need it and therefore could be used to indicate that the next byte is to set an analog value (or the next two bytes if it is a high res DAC like yours), this would simplify the job that the arduino does and give full control to the gen 6, this would make switching on digital output 4 on the arduino from the gen 6 as simple as sending B00010100 down the i2c line and make setting an analog value as simple as sending these three: B10000000 B00111111 B11111111 (this example would set the 14 bit analog output to its maximum output) this would just turn the arduino into a simple i2c IO expander

#include "Wire.h"

//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;
int ledPin = 2;                 // LED connected to digital pin 2

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial
//Test gcode, this should send the machine's X, Y and Z to home
  sendGCode("G28 X0 Y0 Z0\n");
}

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    if (c = '1') 
    {
      //turn dispenser on
      digitalWrite(2, HIGH); //replace the number 2 with the dispenser pin number
    }
    if (c = '0') 
    {
      //turn dispenser off
      digitalWrite(2, LOW);
    }
  }
}

void sendGCode(char* GCode)
{
  Wire.beginTransmission(REP_RAP_ADDR);
  Wire.send(GCode);
  Wire.endTransmission();   
}

void loop()
{
  
}

#ifndef ACCELERATION_ON
  #define ACCELERATION_ON
#endif

//#ifndef ACCELERATION_ON
//  #define ACCELERATION_ON
//#endif

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    Serial.print(c);         // print the character       
  }
}

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    if (c = '1') 
    {
      //turn dispenser on
      digitalWrite(4, HIGH); //replace the number 4 with the dispenser pin number (if it isn't 4, or better yet, define a constant)
    }
    if (c = '0') 
    {
      //turn dispenser off
      digitalWrite(4, LOW);
    }
  }
}

if (dda_counter.e > 0)
			{
                                
				do_e_step();
                                real_move = true;
				dda_counter.e -= total_steps;
				
				if (e_direction)
					current_steps.e++;
				else
					current_steps.e--;
			}

if (dda_counter.e > 0)
			{
                                Wire.send('1'); //tell the arduino to dispense powder
				do_e_step();
                                real_move = true;
				dda_counter.e -= total_steps;
				
				if (e_direction)
					current_steps.e++;
				else
					current_steps.e--;
			} else {Wire.send('0');} //tell the arduino to stop

Quote

....when you say "the printer", do you refer only to the machine and it's gen 6 or the entire system including your arduino?

Quote

the easiest way to do this is to use a simple command system, so for example you could make the arduino interpret the character '1' as "Turn on the dispenser" (in the receive event in the arduino you just need a simple if statement to do this) then when you want the gen6 to turn it on simply send the arduino the character '1', similarly, you can make '0' be the command to turn it off. This system isn't great if you need lots of different values on the DAC as there could only be 256 unique commands (8 bit binary, 0 to 255).

Quote

3- Digital signal will have 1 and 0 states i.e.,
when it is 1, the printer should be printing and
when 0, not printing. Analogue signal will be
controlling the amplitude/amount of powder
dispensed. More voltage, more powder dispensed,
low voltage, less powder dispensed.

#include "Wire.h"
#include "SPI.h" // necessary library
int del=2.5; // used for various delays
word outputValue = 0; // a word is a 16-bit number
byte data = 0; // and a byte is an 8-bit number
int ledPin = 2;                 // LED connected to digital pin 2


//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    Serial.print(c);         // print the character       
  }
}

void sendGCode(char* GCode)
{
  Wire.beginTransmission(REP_RAP_ADDR);
  Wire.send(GCode);
  Wire.endTransmission();   
}

void setup()
{
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial

  //Test gcode, this should send the machine's X, Y and Z to home
  sendGCode("G28 X0 Y0 Z0\n");
pinMode(ledPin, OUTPUT);      // sets the digital pin as output
  //set pin(s) to input and output
  pinMode(10, OUTPUT);
  SPI.begin(); // wake up the SPI bus.
  SPI.setBitOrder(MSBFIRST);

}

void loop()
{
{
  digitalWrite(ledPin, HIGH);   // sets the LED on
  delay(1000);                  // waits for a second
  digitalWrite(ledPin, LOW);    // sets the LED off
  delay(1000);                  // waits for a second
}
 for (int a=0; a<=4095; a++)
  {
    outputValue = a;
    digitalWrite(10, LOW);
    data = highByte(outputValue);
    data = 0b00001111 & data;
    data = 0b00110000 | data;
    SPI.transfer(data);
    data = lowByte(outputValue);
    SPI.transfer(data);
    digitalWrite(10, HIGH);
    delay(del);
  }
  delay(del+25);
  for (int a=4095; a>=0; --a)
  {
    outputValue = a;
    digitalWrite(10, LOW);
    data = highByte(outputValue);
    data = 0b00001111 & data;
    data = 0b00110000 | data;
    SPI.transfer(data);
    data = lowByte(outputValue);
    SPI.transfer(data);
    digitalWrite(10, HIGH);
    delay(del);
  }
  delay(del+25);
}

#include 
int ledPin = 2;   

volatile long last_received_time;

//my address
int CP_ADDR = 5;

void receiveEvent(int howMany)
{  

  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    last_received_time = millis ();  // remember when we last got something
  }
}

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial
}

void loop()
{

  // light LED if we received data in the last second

  if (millis () - last_received_time < 1000)  // if something in the last second
    digitalWrite(ledPin, HIGH);
  else
    digitalWrite(ledPin, LOW);

  // any other stuff
}

.......
         tempControllerState = TEMPREG_INIT;
      }
    }
  #endif
#endif

void receiveEvent(int howMany)
{

}

void requestEvent()
{
  Wire.send("start");
}

SPI.init ()
void setup()
{
  disableTimerInterrupt();
  setupTimerInterrupt();
........

#include "Wire.h"

//i2c address of the gen 6
int REP_RAP_ADDR = 4;
//my address
int CP_ADDR = 5;

void receiveEvent(int howMany)
{
  while(0 < Wire.available()) // loop through all
  {
    char c = Wire.receive(); // receive byte as a character
    Serial.print(c);         // print the character       
  }
}

void sendGCode(char* GCode)
{
  Wire.beginTransmission(REP_RAP_ADDR);
  Wire.send(GCode);
  Wire.endTransmission();   
}

void setup()
{
  Wire.begin(CP_ADDR);
  Wire.onReceive(receiveEvent); // register event so that anything received on i2c is sent to the serial

  //Test gcode, this should send the machine's X and Y to home
  sendGCode("G28 X0 Y0\n");
}

void loop()
{
  
}

sendGCode("G28 X0 Y0\n");

bool cartesian_dda::can_step(int min_pin, int max_pin, long current, long target, bool dir, bool inv)
{

//stop if gone too far on x
    if (max_pin == X_MAX_PIN && dir) //if this is x movement away from origin
    {
      if ((current/X_STEPS_PER_MM)>=100) //going beyond 100?
        return false; //oh no you're not! :-)
    }