Since I could not find a good sketch for this shield I thought I would try to make one and by way, My first contribution to the Arduino society.
So for those whom might need a demo sketch:
//----------------------------------------------------------------------
/*
This is an unofficial demo sketch for using the Official
'Arduino Motor Shield R3' and used as a unipolar/bipolar
stepper driver.
By Duane Bishop Jan-7-2012
This code is public domain.
Prerequisites:
Official Aruino Motor Shield R3 or a pin compatible clone.
(Clones are assumed to be based on L298 driver chip.)
An Arduino Uno, Decimillia, Mega, or clone that can use
the Motor Shield.
Read the product info page at:
Correct wiring knowledge for your stepper motor.
A good guide can be found at:
Know how many steps our motor has.
(If unknown, spin stepper shaft by hand, count detents per
revolution multiply by two and you'll have the correct number
of steps for that model of stepper.)
*/
// How many steps does your stepper have?
int numberOfSteps=200;
// How many milliamps would you like to send to your stepper?
int milliAmps=100; // Per coil.
//Optional
boolean heatsink=false; // If you have one mounted, set to true.
// Import the stepper library.
#include <Stepper.h>
// Label our pins:
int coilA=12; // Coil-A directional pin.
int coilB=13; // Coil-B directional pin.
int coilApower=3; // PWM is used for Coil-A current control.
int coilBpower=11; // PWM is used for Coil-B current control.
int coilAsens=A0; // Used to monitor current draw of Coil-A
int coilBsens=A1; // Used to monitor current draw of Coil-A
// Define some variables we'll need.
int currentOfCoilA;
int currentOfCoilB;
// We'll need a function to derive how many milliamps we're using.
int getMilliamps(int sensingPin)
{
/*
Arduino references 0~5 volts as value of 0~1023
But our Motor Control Shield references its load from 0~3.3 volts.
We need to scale these two ranges so we can make use of it.
So: 1024/5=204.8 per volt. times that by 3.3 we get 675.84
However:
analogRead(); doesn't do decimals so it will only read a maximum
of 675 (at 2 Amps) on our coil sensing pins.
*/
int milliSens=0;
long sensingTotal=0;
while(milliSens <=255) // Gather readings over whole PWM cycle.
{
sensingTotal=sensingTotal + analogRead(sensingPin);
milliSens++;
}
int sensingAvg=sensingTotal/256; // Average the readings
int milliLoad=map(sensingAvg,0,675,0,2000); //Translate to milliamps
return(milliLoad); //Return the result.
}
void setCoilPower(int power)
{
int tempVal=0;
while(getMilliamps(coilAsens) < power)
{
tempVal++;
analogWrite(coilApower,tempVal);
}
Serial.print("Setting coilApower=");
Serial.print(tempVal);
tempVal=0;
while(getMilliamps(coilBsens) < power)
{
tempVal++;
analogWrite(coilBpower,tempVal);
}
Serial.print(" and coilBpower=");
Serial.println(tempVal);
Serial.println("");
}
// Now we'll make our stepper funtion.
Stepper ourStepperFunction(numberOfSteps,coilA,coilB);
void setup()
{
// Set our pinModes.
pinMode(coilA,OUTPUT);
pinMode(coilB,OUTPUT);
pinMode(coilApower,OUTPUT);
pinMode(coilBpower,OUTPUT);
pinMode(coilAsens,INPUT);
pinMode(coilBsens,INPUT);
// Set the speed of our stepper.
// (Faster = less torque. 100 is very slow, but very reliable.)
ourStepperFunction.setSpeed(25);
Serial.begin(9600); // Open you serial monitor to view results.
// Sanity check.
if(milliAmps > 2000)
{
Serial.println("milliAmps: Set WAY TOO HIGH!!");
Serial.println("milliAmps: You'll SMOKE your Motor Controller!!");
Serial.println("Bailing out. Mayday! Mayday!");
while(milliAmps); // Stay here do not pass.
}else{
if(milliAmps >= 1000 && heatsink != true)
{
Serial.println("milliAmps: Set too high for stock Motor Shield!");
Serial.println("milliamps:Install heatsink and set 'heatsink=true'");
Serial.println("Bailing out.");
while(milliAmps); // Stay here do not pass.
}else{
Serial.println("milliamps: OK.");
delay(500);
Serial.print("Ramping power up to: ");
Serial.print(milliAmps);
Serial.println(" milliAmps for each coil.");
setCoilPower(milliAmps);
Serial.println("Your stepper should now be turning one revolution");
Serial.println(" in each direction. If not, check your wires.");
Serial.println(" It the stepper/driver is hot, lower your milliAmps.");
}
}
}
void loop()
{
ourStepperFunction.step(numberOfSteps);
delay(500);
ourStepperFunction.step(-numberOfSteps);
}