Raspberry PI & Arduino - Blynk Stepper Control

This tutorial will show you how to control a stepper motor with an Arduino, a Raspberry Pi and the Blynk Application.

In a nut shell, the app sends requests to the Raspberry Pi via Virtual Pins, the Pi then sends HIGH/LOW signal to the Arduino and the Arduino then deals with the stepper motor.

I think that it is easier to use that approch since most people are used to work with Arduino and not a lot with node.js on the Raspberry Pi.

Components needed for this :

- Raspberry PI ( I am using the Raspberry Pi 3 model b )

- Arduino ( I am using an Arduino Nano )

- Servo Motor ( I am using a 28BYJ-48 5VDC with its controller )

- Some jumper wires

- Power source (5VDC 2A.)

The Arduino sketch and the Node.js code is available to download. Just look up the files.

Step 1: Creating the App on Your Phone

Download Blynk from the AppStore or GooglePlay

Open the App and create a user or Log In with facebook.

- Create a new project

Name your project : MyProject

Choose Device : Rasapberry Pi 3 B

Connection Type : Wifi (or Ethernet if your Pi is wired to your network)

- Click Create

Check your email for your Token

(looks like this 3aa19bb8a9e64c90af11e3f6b0595b3c)

This Token is bonded with your current app. If you do another app, you will generate another token.

In the App add the following widgets (see picture)

- Add 3 buttons

- Add 1 LCD

- Edit the button

name the first one Command1, set the Pin as Virtual Pin 1 and set the Mode as SWITCH

name the second one CW, set the Pin as Virtual Pin 2 and set the Mode as PUSH

name the third one CCW, set the Pin as Virtual Pin 3 and set the Mode as PUSH

- Edit the LCD

set the Pins as Virtual Pin 4 and Virtual Pin 5 and set the Mode to PUSH

Step 2: Getting the PI Ready

First, you need to install Node.js.
Before updating Node.js, please be sure to remove old versions:

Open Terminal and type

sudo apt-get purge node nodejs

node.js -ysudo apt-get autoremove

Automatic Node.js installation Add repositories:

curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -

Install Node.js

sudo apt-get update && sudo apt-get upgrade

sudo apt-get install build-essential nodejs -y

Once Node.js is installed, Install Blynk

sudo npm install blynk-library -g

sudo npm install onoff -g

Step 3: Creating Your Project

Start by changing directory (cd command) to the pi directory

Open Terminal and type:

cd /home/pi/

Then, create a directory where your project will reside

mkdir MyProject

Change directory to MyProject, type the following in the Terminal

cd MyProject

Check the content of the directory (it should be empty). Just type the following in the Terminal

ls

Next, type the following to create your project description (package.json)

npm init

Just type the project name, author, version, etc...

Once this is done, install the Blynk library, the onoff library and the system-sleep library in YOUR project directory. Type the following in your Terminal

npm install blynk-library --save

npm install onoff --save

npm install system-sleep --save

Finally, create your .js file (This will be where your code will reside). Type the following in the Terminal

nano MyProject.js

Once you execute that command, nano (terminal text editor) will open.

Step 4: MyProject.js

In nano, write the following lines of code

var Blynk = require('blynk-library');

var AUTH = ' ****************** '; THIS IS YOUR TOKEN

var blynk = new Blynk.Blynk(AUTH);

var Gpio = require('onoff').Gpio,

command1 = new Gpio(18, 'out'), //Will be connected to Arduino D2

commandCW = new Gpio(23, 'out'), //Will be connected to Arduino D3

commandCCW = new Gpio(24, 'out'); //Will be connected to Arduino D4

var sleep = require('system-sleep');

var v1 = new blynk.VirtualPin(1); //this is your Command1 button in the app

var v2 = new blynk.VirtualPin(2); //this is your CW button in the app

var v3 = new blynk.VirtualPin(3); //this is your CCW button in the app

var v4 = new blynk.VirtualPin(4); //this is your LCD line 1 in the app

var v5 = new blynk.VirtualPin(5); //this is your LCD line 2 in the app

v1.on('write', function (param) //Check for the Command1 button in the app

{

if (param == 1) //If the button is pressed (which is 1) then do the following

{

v4.write("Executing"); //Write "Executing" on the first line of the LCD

v5.write("Command"); //Write "Command" on the second line of the LCD

command1.writeSync(1); //Set the GPIO18 (which is variable command1) to 1 (HIGH)

sleep(4000); //Wait for 4 seconds

command1.writeSync(0); //Set the GPIO18 (which is variable command1) to 0 (LOW)

v4.write("Done"); //Write "Done" on the first line of the LCD

v5.write(" "); //Write " " (nothing) on the second line of the LCD

v1.write(0); //Write 0 to your Command1 button, that will reset it to the OFF position

}

});

v2.on('write', function (param) //Check for the CW button in the app

{

if (param == 1) //If the button is pressed (which is 1) then do the following

{

commandCW.writeSync(1); //Set the GPIO23 (which is variable commandCW) to 1 (HIGH)

}

else if (param == 0) //If the button not pressed (which is 0) then do the following

{

commadCW.writeSync(0); //Set the GPIO23 (which is variable commandCW) to 0 (LOW)

}

});

v3.on('write', function (param) //Check for the CCW button in the app

{

if (param == 1) //If the button is pressed (which is 1) then do the following

{

commandCCW.writeSync(1); //Set the GPIO24 (which is variable commandCCW) to 1 (HIGH)

}

else if (param == 0) //If the button not pressed (which is 0) then do the following

{

commandCCW.writeSync(0); //Set the GPIO24 (which is variable commandCCW) to 1 (HIGH)

}

});

------------------------------------------------------------------------------------------------------------------------------------------------------

Save it and exit nano

- to save CTRL+O

- to quit CTRL+X

You are done with the Raspberry Pi.

Now test it to see if have any kind of errors (most of the time are Typo errors)

To test it, simply type the following in your Terminal

node MyProject.js

You should get an output that looks like this

OnOff mode

Connecting to: blynk-cloud.com 8441

SSL authorization...

Authorized

Step 5: MyProject in Arduino

Ok so now we have 2/3 things completed!

Now we just need to write some code for the Arduino.

- Create a new Arduino sketch and type the following code.

#include

#define STEPS_PER_MOTOR_REVOLUTION 32

#define STEPS_PER_OUTPUT_REVOLUTION 32 * 64 //2048

//The pin connections need to be pins 8,9,10,11 connected

// to Motor Driver In1, In2, In3, In4

// Then the pins are entered here in the sequence 1-3-2-4 for proper sequencing

Stepper small_stepper(STEPS_PER_MOTOR_REVOLUTION, 8, 10, 9, 11);

int Steps2Take;

int Command1;

int CommandCW;

int CommandCCW;

void setup()

{

pinMode(2, INPUT);

pinMode(3, INPUT);

pinMode(4, INPUT);

//(Stepper Library sets pins as outputs)

}

void loop()

{

Command1 = digitalRead(2);

CommandCW = digitalRead(3);

CommandCCW = digitalRead(4);

if(Command1 == 0)

{

//do nothing

}

else

{

ExecutionFunction();

}

if(CommandCW == 1)

{

small_stepper.setSpeed(700);

small_stepper.step(-1);

delay(1);

}

if(CommandCCW ==1)

{

small_stepper.setSpeed(700);

small_stepper.step(1);

delay(1);

}

}

void ExecutionFunction()

{

Steps2Take = STEPS_PER_OUTPUT_REVOLUTION / 4 ; // Rotate CCW 1/4 turn

small_stepper.setSpeed(700);

small_stepper.step(Steps2Take); // You can replace Steps2Take with any value between 0 and 2048

delay(500);

Steps2Take = - STEPS_PER_OUTPUT_REVOLUTION / 4; // Rotate CW 1/4 turn

small_stepper.setSpeed(700);

small_stepper.step(Steps2Take); // You can replace Steps2Take with any value between 0 and 2048

delay(2000);

}

Compile and upload to your Arduino.

Now make sure you connect everything correctly! See the next step for wiring.

Step 6: Wiring

Connect Arduino D3 to RaspberryPi GPIO18 (which is actually pin 12)

Connect Arduino D4 to RaspberryPi GPIO23 (which is actually pin 16)

Connect Arduino D4 to RaspberryPi GPIO24 (which is actually pin 18)

Connect Arduino GND to RaspberryPi GND (pin 6)

Connect Arduino D8 to Stepper Controller In1

Connect Arduino D9 to Stepper Controller In2

Connect Arduino D10 to Stepper Controller In3

Connect Arduino D11 to Stepper Controller In4

Connect 5VDC to Arduino, Raspberry Pi and Stepper Controller

Step 7: That's It!

Check the video, and you should be finished!

Thanks and enjoy!