Code:
/*  FILE:    HC_CNC_Shield_Test
    DATE:    21/10/14
    VERSION: 0.1
    AUTHOR:  Andrew Davies

This is an example sketch which tests some of the functions of the Hobby 
Components CNC shield (HCARDU0086). The sketch will step the X, Y Z, and Aux 
stepper outputs in both directions. It will also report if any of the endstop
or control inputs have been triggered via the serial port. 

WARNING: Ensure that your stepper motors are mechanically disconnected before 
running this sketch as it will not stop drive to the motors should an endstop be 
reached.

If you are using the Aux stepper output you will need to connect the pins labelled
D13 to A-DIR and D12 to A-STEP on the shield.

You may copy, alter and reuse this code in any way you like, but please leave
reference to HobbyComponents.com in your comments if you redistribute this code.
This software may not be used directly for the purpose of selling products that
directly compete with Hobby Components Ltd's own range of products.

THIS SOFTWARE IS PROVIDED "AS IS". HOBBY COMPONENTS MAKES NO WARRANTIES, 
WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ACCURACY OR
LACK OF NEGLIGENCE. HOBBY COMPONENTS SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE
FOR ANY DAMAGES INCLUDING, BUT NOT LIMITED TO, SPECIAL, INCIDENTAL OR 
CONSEQUENTIAL DAMAGES FOR ANY REASON WHATSOEVER.
*/


#define EN 8      /* Enable pin for all stepper outputs */

#define X_DIR 5   /* Direction pin for X axis */
#define X_STEP 2  /* Step pin for X axis */

#define Y_DIR 6   /* Direction pin for Y axis */
#define Y_STEP 3  /* Step pin for Y axis */

#define Z_DIR 7   /* Direction pin for Z axis */
#define Z_STEP 4  /* Step pin for Z axis */

#define A_DIR 13  /* Direction pin for Aux driver. Requires D13 and A-DIR pins to be shorted */
#define A_STEP 12 /* Direction pin for Aux driver. Requires D12 and A-STEP pins to be shorted */

#define X_ENDSTOP 9   /* X axis endstop input pin */
#define Y_ENDSTOP 10  /* Y axis endstop input pin */
#define Z_ENDSTOP 11  /* Z axis endstop input pin */
#define ABORT A0  /* Abort input pin */
#define HOLD A1   /* Hold input pin */
#define RESUME A2 /* Resume input pin */

int Count = 0; /* Counter to count number of steps made */
boolean Direction = LOW; /* Rotational direction of stepper motors */

/* The setup routine runs once when you press reset: */
void setup() 
{                
  /* Initialize serial */
  Serial.begin(9600);
  
  /* Configure the steper drive pins as outputs */ 
  pinMode(EN, OUTPUT); 
  pinMode(X_DIR, OUTPUT); 
  pinMode(X_STEP, OUTPUT); 
  pinMode(Y_DIR, OUTPUT); 
  pinMode(Y_STEP, OUTPUT); 
  pinMode(Z_DIR, OUTPUT); 
  pinMode(Z_STEP, OUTPUT); 
  pinMode(A_DIR, OUTPUT); 
  pinMode(A_STEP, OUTPUT); 
  
  /* Configure the control pins as inputs with pullups */
  pinMode(X_ENDSTOP, INPUT_PULLUP);
  pinMode(Y_ENDSTOP, INPUT_PULLUP);
  pinMode(Z_ENDSTOP, INPUT_PULLUP);

  pinMode(ABORT, INPUT_PULLUP);
  pinMode(HOLD, INPUT_PULLUP);
  pinMode(RESUME, INPUT_PULLUP);

  /* Enable the X, Y, Z & Aux stepper outputs */
  digitalWrite(EN, LOW); //Low to enable
}

// the loop routine runs over and over again forever:
void loop() 
{
  /* Count one step */
  Count++;
    
  /* If we have reached 500 steps then change the stepper direction and reset the counter */
  if (Count >= 500)
  {
    Direction = !Direction;
    digitalWrite(X_DIR, Direction); // Low = CW 
    digitalWrite(Y_DIR, Direction); // Low = CW 
    digitalWrite(Z_DIR, Direction); // Low = CW 
    digitalWrite(A_DIR, Direction); // Low = CW 
    Count = 0;
  }
    
  /* Step the X, Y, Z, and Aux motors */  
  digitalWrite(X_STEP, HIGH); 
  delay(1); 
  digitalWrite(Y_STEP, HIGH); 
  delay(1); 
  digitalWrite(Z_STEP, HIGH); 
  delay(1);    
  digitalWrite(A_STEP, HIGH); 
  delay(1); 
  
  digitalWrite(X_STEP, LOW);  
  delay(1); 
  digitalWrite(Y_STEP, LOW); 
  delay(1); 
  digitalWrite(Z_STEP, LOW);  
  delay(1); 
  digitalWrite(A_STEP, LOW);  
  delay(1);
  
  /* Check state of inputs */
  if (!digitalRead(X_ENDSTOP)) Serial.println("X-axis end-stop triggered!"); 
  if (!digitalRead(Y_ENDSTOP)) Serial.println("Y-axis end-stop triggered!"); 
  if (!digitalRead(Z_ENDSTOP)) Serial.println("Z-axis end-stop triggered!"); 
  if (!digitalRead(ABORT)) Serial.println("Abort input triggered!"); 
  if (!digitalRead(HOLD)) Serial.println("Hold input triggered!"); 
  if (!digitalRead(RESUME)) Serial.println("Resume input triggered!"); 
}