Example Sketch for Adafruit Stepper Shield

This is adapted from a sketch written by Ray from the RMWeb Forum. Thank you Ray for your inspiration and help.

// DCC Turntable Control - Ian Jeffery

#include <DCC_Decoder.h>
#include <AccelStepper.h>
#include <Wire.h>
#include <Adafruit_MotorShield.h>
#include "utility/Adafruit_MS_PWMServoDriver.h"

//
// Defines and structures
//
#define cDCC_INTERRUPT   0

typedef struct
{
	int address;
	int stationFront;
	int stationBack;
}
DCCAccessoryAddress;
DCCAccessoryAddress gAddresses[17];

int cNudge = 5; // nudge it forward a few steps.
#define cStartOfNudgeAddresses 12

//
// Adafruit Setup

Adafruit_MotorShield AFMStop(0x60); // Default address, no jumpers

// Connect stepper with 200 steps per revolution (1.8 degree)
// to the M3, M4 terminals (blue,yellow,green,red)

Adafruit_StepperMotor *myStepper2 = AFMStop.getStepper(200, 2);

// you can change these to SINGLE, DOUBLE, INTERLEAVE or MICROSTEP!
// wrapper for the motor! (3200 Microsteps/revolution)
void forwardstep2() {
	myStepper2->onestep(FORWARD, MICROSTEP);
}
void backwardstep2() {
	myStepper2->onestep(BACKWARD, MICROSTEP);
}

void release2()
{
	Serial.println(F("Powering Down Motor "));
	myStepper2->release();
}

// Now we'll wrap the stepper in an AccelStepper object

AccelStepper stepper2(forwardstep2, backwardstep2);

#define entryStation 906

//
// Decoder Init 
//
void ConfigureDecoder()
{
	// this is home
	gAddresses[0].address = 299;
	gAddresses[0].stationFront = 10;
	gAddresses[0].stationBack = 3190;

	gAddresses[1].address = 200;
	gAddresses[1].stationFront = 906;
	gAddresses[1].stationBack = 2506;

	gAddresses[2].address = 201;
	gAddresses[2].stationFront = 1692;
	gAddresses[2].stationBack = 82;

	gAddresses[3].address = 202;
	gAddresses[3].stationFront = 1802;
	gAddresses[3].stationBack = 202;

	gAddresses[4].address = 203;
	gAddresses[4].stationFront = 1921;
	gAddresses[4].stationBack = 321;

	gAddresses[5].address = 204;
	gAddresses[5].stationFront = 2040;
	gAddresses[5].stationBack = 428;

	gAddresses[6].address = 205;
	gAddresses[6].stationFront = 2142;
	gAddresses[6].stationBack = 536;

	gAddresses[7].address = 206;
	gAddresses[7].stationFront = 2266;
	gAddresses[7].stationBack = 1100;

	gAddresses[8].address = 207;
	gAddresses[8].stationFront = 2392;
	gAddresses[8].stationBack = 1300;

	gAddresses[9].address = 208;
	gAddresses[9].stationFront = 2515;
	gAddresses[9].stationBack = 1500;

	gAddresses[10].address = 209;
	gAddresses[10].stationFront = 2634;
	gAddresses[10].stationBack = 1700;

	gAddresses[11].address = 210;
	gAddresses[11].stationFront = 2736;
	gAddresses[11].stationBack = 1900;

	
	// these are the nudge addresses
	gAddresses[12].address = 300;
	gAddresses[13].address = 301;
	gAddresses[14].address = 302;
	gAddresses[15].address = 303;

	// this is the powerdown address
	gAddresses[16].address = 399;
}

void moveTurnTable(int position)
{
	// This moves the turntable, and then shuts off the power to the motor
	Serial.print(F("Moving to Position : "));
	Serial.println(position, DEC);
	stepper2.moveTo(position);
	Serial.print("Distance to Position : ");
	Serial.println(abs(stepper2.distanceToGo()), DEC);

	while (abs(stepper2.distanceToGo()) > 0)
	{
		stepper2.run();
	}
	Serial.print(F("Moved to Position."));
	delay(1000);
	release2();
}

//
// Accessory packet handler - This is where we react to DCC Addresses
//
void BasicAccDecoderPacket_Handler(int address, boolean activate, byte data)
{
	// Convert NMRA packet address format to human address
	address -= 1;
	address *= 4;
	address += 1;
	address += (data & 0x06) >> 1;
	boolean enable = (data & 0x01) ? 1 : 0;

	Serial.print(F("Basic addr: "));
	Serial.print(address, DEC);
	Serial.print(F("   activate: "));
	Serial.println(enable, DEC);

	for (int i = 0; i<(int)(sizeof(gAddresses) / sizeof(gAddresses[0])); i++)
	{
		if (address == gAddresses[i].address)
		{
			Serial.print(F("Moving to Station : "));
			Serial.println(i, DEC);

			if (enable)
			{
				if (i < cStartOfNudgeAddresses)
				{
					moveTurnTable(gAddresses[i].stationFront);
					break;
				}
				else
					switch (i)
					{
						// nudge addresses  
					case 12:
						Serial.print(F("Nudging forward 5 steps : "));
						moveTurnTable(stepper2.currentPosition() + cNudge);
						break;
					case 13:
						Serial.print(F("Nudging forward 10 steps : "));
						moveTurnTable(stepper2.currentPosition() + (cNudge * 2));
						break;
					case 14:
						Serial.print(F("Nudging forward 50 steps : "));
						moveTurnTable(stepper2.currentPosition() + (cNudge * 4));
						break;
					case 15:
						Serial.print(F("Nudging forward 100 steps : "));
						moveTurnTable(stepper2.currentPosition() + (cNudge * 20));
						break;
					case 16:
						Serial.println(F("Powering Down Motor "));
						release2();
						break;
					}
			}
			else
			{
				if (i < cStartOfNudgeAddresses)
				{
					moveTurnTable(gAddresses[i].stationBack);
					break;
				}
				else
					switch (i)
					{
						// nudge addresses  
					case 12:
						Serial.print(F("Nudging backwards 5 steps : "));
						moveTurnTable(stepper2.currentPosition() - cNudge);
						break;
					case 13:
						Serial.print(F("Nudging backwards 10 steps : "));
						moveTurnTable(stepper2.currentPosition() - (cNudge * 2));
						break;
					case 14:
						Serial.print(F("Nudging backwards 50 steps : "));
						moveTurnTable(stepper2.currentPosition() - (cNudge * 4));
						break;
					case 15:
						Serial.print(F("Nudging backwards 100 steps : "));
						moveTurnTable(stepper2.currentPosition() - (cNudge * 20));
						break;
					case 16:
						Serial.println(F("Powering Down Motor "));
						release2();
						break;
					}
			}
		}
	}
}

//
// Setup
//
void setup()
{
	Serial.begin(9600);

	AFMStop.begin(); // Start the shield

	//configure pin3 as an input and enable the internal pull-up resistor
	pinMode(3, INPUT_PULLUP);
	//read the sensor (open collector type) value into a variable
	int sensorVal = digitalRead(3);

	//set stepper motor speed and acceleration 
	stepper2.setMaxSpeed(100.0);
	stepper2.setAcceleration(20.0);
	//  

	// if near reference point move away
	sensorVal = digitalRead(3);
	while (sensorVal == LOW) {
		sensorVal = digitalRead(3);
		forwardstep2();
		delay(25);
	}

	// step forward to sensor index point
	while (sensorVal == HIGH) {
		sensorVal = digitalRead(3);
		forwardstep2();
		delay(25);
	}

	stepper2.setMaxSpeed(35.0);

	Serial.println(F("Moving to entry station"));
	stepper2.moveTo(entryStation);
	stepper2.runToPosition();
	delay(2000);
	// Power down the Stepper Motor
	release2();

	DCC.SetBasicAccessoryDecoderPacketHandler(BasicAccDecoderPacket_Handler, true);
	ConfigureDecoder();
	DCC.SetupDecoder(0x00, 0x00, cDCC_INTERRUPT);
}

//
// Main loop
//
void loop()
{
	// Loop DCC library
	DCC.loop();
	// Loop the Stepper Motor Library
	stepper2.run();
	
}