Easy Driver Hook-up Guide

Contributors: Toni_K

Arduino Code

Basic Arduino Code Example

Now that you have the hardware hooked up and ready to go, it's time to get the code uploaded. For the most up-to-date code available, please check the GitHub repository. First, download and unzip the example sketch. Navigate to Easy_Driver > Firmware > SparkFun_Easy_Driver_Basic_Demo > SparkFun_Easy_Driver_Basic_Demo.ino example and open it in the Arduino IDE.

The first section of the sketch defines all of the pin connections between the RedBoard and the Easy Driver. It also sets these pins as outputs, and puts them to the proper logic levels to begin driving the motor.

language:c
 //Declare pin functions on RedBoard
#define stp 2
#define dir 3
#define MS1 4
#define MS2 5
#define EN  6

//Declare variables for functions
char user_input;
int x;
int y;
int state;

void setup() {
  pinMode(stp, OUTPUT);
  pinMode(dir, OUTPUT);
  pinMode(MS1, OUTPUT);
  pinMode(MS2, OUTPUT);
  pinMode(EN, OUTPUT);
  resetEDPins(); //Set step, direction, microstep and enable pins to default states
  Serial.begin(9600); //Open Serial connection for debugging
  Serial.println("Begin motor control");
  Serial.println();
  //Print function list for user selection
  Serial.println("Enter number for control option:");
  Serial.println("1. Turn at default microstep mode.");
  Serial.println("2. Reverse direction at default microstep mode.");
  Serial.println("3. Turn at 1/8th microstep mode.");
  Serial.println("4. Step forward and reverse directions.");
  Serial.println();
}

One thing worth noting is that the code also initializes the serial connection at 9600 bps. This enables the user (you!) to control the motor's functionality and debug your circuit if needed.

The main loop of the code is pretty simple. The RedBoard scans the serial port for input from the user. When it is received, it's compared to the four possible functions for the motor, which are triggered from user input. If no valid input is received, the RedBoard prints an error over the serial port. After the requested function is completed, the pins on the Easy Driver are reset to the defaults.

language:c
 //Main loop
void loop() {
  while(Serial.available()){
      user_input = Serial.read(); //Read user input and trigger appropriate function
      digitalWrite(EN, LOW); //Pull enable pin low to allow motor control
      if (user_input =='1')
      {
         StepForwardDefault();
      }
      else if(user_input =='2')
      {
        ReverseStepDefault();
      }
      else if(user_input =='3')
      {
        SmallStepMode();
      }
      else if(user_input =='4')
      {
        ForwardBackwardStep();
      }
      else
      {
        Serial.println("Invalid option entered.");
      }
      resetEDPins();
  }
}

Driving Stepper Motor in Forward

The first of the four functions this demo sketch enables is a basic example to show the motor spinning in one direction. The direction pin is held LOW, which for our sketch, we define as the 'forward' direction. The sketch then transitions the step pin HIGH, pauses, and then pulls it LOW. Remember, the motor only steps when the step pin transitions from LOW to HIGH, thus we have to switch the state of the pin back and forth. This is repeated 1000 times, and then the RedBoard requests more user input to determine the next motor activity.

language:c
//Default microstep mode function
void StepForwardDefault()
{
  Serial.println("Moving forward at default step mode.");
  digitalWrite(dir, LOW); //Pull direction pin low to move "forward"
  for(x= 0; x<1000; x++)  //Loop the forward stepping enough times for motion to be visible
  {
    digitalWrite(stp,HIGH); //Trigger one step forward
    delay(1);
    digitalWrite(stp,LOW); //Pull step pin low so it can be triggered again
    delay(1);
  }
  Serial.println("Enter new option");
  Serial.println();
}

Driving Stepper Motor in Reverse

The reverse function works exactly the same as the forward function. The only difference is that instead of pulling the direction pin LOW, we set it HIGH, thus switching the direction of the motor spin. One thing you can try on either of these first two functions is modifying the motor speed by changing the value in delay(). It is currently set to 1 millisecond, making each step pulse take 2 milliseconds. Increasing the delay will slow down the motor, while decreasing the delay will speed up the motor.

language:c
//Reverse default microstep mode function
void ReverseStepDefault()
{
  Serial.println("Moving in reverse at default step mode.");
  digitalWrite(dir, HIGH); //Pull direction pin high to move in "reverse"
  for(x= 0; x<1000; x++)  //Loop the stepping enough times for motion to be visible
  {
    digitalWrite(stp,HIGH); //Trigger one step
    delay(1);
    digitalWrite(stp,LOW); //Pull step pin low so it can be triggered again
    delay(1);
  }
  Serial.println("Enter new option");
  Serial.println();
}

Microstepping

The third function shows off the different microstepping functionality that the Easy Driver provides. To enable the motor to step in 1/8th microsteps, we must set MS1, and MS2 HIGH. This sets the logic of the board to 1/8th microstep mode. If you want to have the motor step at a different microstep mode, change the settings for one of the MS# pins. Check the truth table in the Hardware Overview section, if you need a reminder of what settings are enabled by the various pin states.

language:c
// 1/8th microstep foward mode function
void SmallStepMode()
{
  Serial.println("Stepping at 1/8th microstep mode.");
  digitalWrite(dir, LOW); //Pull direction pin low to move "forward"
  digitalWrite(MS1, HIGH); //Pull MS1, and MS2 high to set logic to 1/8th microstep resolution
  digitalWrite(MS2, HIGH);
  for(x= 0; x<1000; x++)  //Loop the forward stepping enough times for motion to be visible
  {
    digitalWrite(stp,HIGH); //Trigger one step forward
    delay(1);
    digitalWrite(stp,LOW); //Pull step pin low so it can be triggered again
    delay(1);
  }
  Serial.println("Enter new option");
  Serial.println();
}

Forward and Reverse

The final motor function available shows how the motor can change direction on the fly. The function works just as the forward and reverse functions above, but switches between states quickly. This example will step the motor 1000 steps forward and then reverse 1000 steps. This allows you to precisely move something with the motor in one direction, and return to the starting position exactly. Precise position control is a great benefit of stepper motors!

language:c
//Forward/reverse stepping function
void ForwardBackwardStep()
{
  Serial.println("Alternate between stepping forward and reverse.");
  for(x= 1; x<5; x++)  //Loop the forward stepping enough times for motion to be visible
  {
    //Read direction pin state and change it
    state=digitalRead(dir);
    if(state == HIGH)
    {
      digitalWrite(dir, LOW);
    }
    else if(state ==LOW)
    {
      digitalWrite(dir,HIGH);
    }

    for(y=0; y<1000; y++)
    {
      digitalWrite(stp,HIGH); //Trigger one step
      delay(1);
      digitalWrite(stp,LOW); //Pull step pin low so it can be triggered again
      delay(1);
    }
  }
  Serial.println("Enter new option:");
  Serial.println();
}

Once the requested action is completed, the pins must be set back to the default state to prevent unexpected or unwanted motor behavior. We use the resetEDPins() function to achieve this.

language:c
//Reset Easy Driver pins to default states
void resetEDPins()
{
  digitalWrite(stp, LOW);
  digitalWrite(dir, LOW);
  digitalWrite(MS1, LOW);
  digitalWrite(MS2, LOW);
  digitalWrite(EN, HIGH);
}

Additional Examples

In addition to the example here, you can also install the AccelStepper Library. There are some additional examples with this library that may be beneficial to you for use with your Easy Driver. Download this and install the library in your Arduino libraries directory.

You can also find some additional examples on Brian's Easy Driver examples page.