#Intro A few words about Blynk. Contents?

#Getting Started ###Download all the ingridients: Blynk App for iOS or Android:

       

Install Blynk Library:

Download Blynk Library >

In case you forgot how to install Arduino libraries: check here. We are also good friends of codebender - you can code and upload Blynk sketches to your gardware directly from your browser.

###Blink With Blynk

Let's start with something easy: turn LED connected to your hardware ON and OFF with the Blynk App

animated gif

Use this wiring scheme to connect LED to your Hardware:

Create Blynk Account In The App

Screenshot / Animation

###Auth Token Auth Token is used to connect your Arduino or other board to your smartphone. Every new project you create will have an Auth Token.

Screenshot / animation

It's very convenient to send it over E-mail. If you press E-mail button – token will be sent to the e-mail address you used for registration. If you have a good memory - you can memorize it ;) or tap the number and it will be copied to the clipboard.

Choose your hardware

Select the hardware you are building project on.

#Let's Get Online You know that Blynk works over the Internet, right? (Bluetooth LE is on the way)

Blynk works with almost anything, check the full list of supported hardware

Before you start Blynking, you need to understand how you will connect to the Internet. It can be an Ethernet Shield for Arduino, or may be your hardware is already internet-enabled (e.g. Spark Core).

###How To Use Example Sketches

Illustration Building Blocks:

• Connection Layer
• Auth Token
• Processing Layer

###Choosing Your Connection Type We've prepared example sketches which will get your microcomputer online. Open the example sketch according to your device or shield. If you are using codebender - find the example you need in the list

###Insert Auth Token

As it was said prevously, Auth Token is used to identify your hardware and connect it with the smartphone.

In the example sketch find this line in code:

char auth[] = "Your AuthToken";

Change it by putting your Auth Token inside curly brackets.

char auth[] = "123456789abcdefghijk0987654321";

If you don't know what is your Auth Token for the project - check the Project Settings in the app. You can send it over the E-mail.

Screenshot from the app

Never post your Auth Token publically, unless you want other people to be able to connect to your project.

Upload sketch to the board and open Serial Terminal. Wait until you see something like this:

Your IP is 192.168.0.11
Connecting...
Blynk connected!

Congratulations! It was the hardest part and it's over!

###Connect over USB, and others

If you don't have any shield and your hardware doen's have any connectivity, you can still use Blynk – directly over USB. It's a bit tricky for newbies, but if you follow these USB instructions you'll succeed for sure. We also work on enhancing this process.

###Raspberry Pi, Spark Core

• Spark Core owners: check here
• Raspberry Pi eaters: here

Set Up Your Project

Open your project in the app. It's empty now, so let's add a Button. Just tap anywhere on empty space - Widget Box will open. Choose the Button Widget.

Screenshot

Hold and drag it to reposition

Screenshot

Tap on the widget to get to it's settings

Screenshot

The most important parameter to set is PIN . List of pins reflects physical pins defined by your hardware. If your LED is connected to Digital Pin 10 - then select D10 (D - stands for Digital). Virtual pins are described here.

Illustration showing how Physical PIN is connected to Pin in the APP.

When you are done with the Settings - press PLAY button. This will switch you from EDIT mode to PLAY mode where you can interact with widgets. You can always get back to EDIT mode by pressing STOP

Screenshot

Press Button to turn the LED On and Off

Screenshot

Always feel free to experiment! For example, attach an LED to PWM-enabled Pin on your Arduino. Set the Slider Widget to control brightness of an LED. Just use the same steps described above.

Happy Blynking!

#Blynk Basics

We prepared example sketches to show main Blynk Features. All the sketches are designed so that it's easy to combine one example with another.

###Virtual Pins Virtual Pins are designed to send any data from microcontroller to the Blynk app and back. Think about Virtual Pins as channels for any variables. They are different to physical pins on your Arduino.

Illustration showing Virtual Pin

There are 32 Virtual pins at your disposal (V0 - V31)

screenshot of pin picker

Blynk.virtualWrite(PIN, VALUE)

Getting and Sending Data

Let's say you want to send converted data from temperature sensor from ºC to ºF and send it to Blynk every 1 second.

Open the sketch accordingly to your hardware. This example is for Ethernet Shield

To avoid using delay(); function, which may cause connection interruptions, we recommend using SimpleTimer library for events that need intervals. Check this example sketch for more details.

Warning: Don't send more that 10 values per second** - otherwise you'll get FLOOD error and your messages will be banned.

void yourTimedEvent()
{
  Blynk.virtualWrite(5, something;)
}

void loop()
{
  Blynk.run(); 
  timer.run(); 
}

How to process data from Blynk App on Arduino

You can use any data from Blynk in your project by using Virtual Pins

BLYNK_WRITE(1)
{
  BLYNK_LOG("Got a value: %s", param.asStr());
}

This command means that hardware is listening to the Widget, that WRITEs data to Virtual Pin 1 in the app.

You can get data as INTs, Floats, Doubles and Strings

  param.asInt());
  param.asFloat());
  param.asDouble());
  param.asStr());

Some Widgets may send an array of values (e.g Joystick, zeRGBa). You can get any parameter of the array by using:

BLYNK_WRITE(1)
{   
  BLYNK_LOG("Got a value: %s", param(2).asInt());
}

Raspberry Pi

Specific steps for Raspberry Pi

Spark Core

Specific steps for Spark Core

#List Of Supported Hardware List of devices goes here

#Widgets

Common Widget Settings

Most of the settings are self-explainable, but there are some hidden features that you can use

Pin Selection

This is one of the main parameters you need to set

Screenshot

Read more about Virtual Pins Here

Data Mapping

Screenshot

Splitting/Merging Outputs

Screenshot

Controls:

Button

Image

Slider

Image

Timer

Image

Joystick

Image

Displays:

Value Display

Image

Graph

Image

LCD Display

Image

Notifications:

Twitter

Twitter Widget connects your Twitter account to Blynk and allows you to send Tweets from your hardware.

Example code:

if (something) 
{
   Blynk.tweet("Hey, Blynkers! My Arduino can tweet now!");
}

Email

Image

Push Notifications

Image

#Blynk Commands The library can perform basic pin IO (input-output) operations out-of-the-box:

digitalRead
digitalWrite
analogRead
analogWrite //PWM or Analog signal depending on the platform

BLYNK_WRITE(vPIN)

BLYNK_READ(vPIN)

Blynk.virtualWrite();

You can send all the formats of data to Virtual Pins

Blynk.virtualWrite(pin, "abc");
Blynk.virtualWrite(pin, 123);
Blynk.virtualWrite(pin, 12.34);

BLYNK_PRINT

BLYNK_LOG

BLYNK_CONNECT();

BLYNK_DEBUG

To enable debug prints on the default Serial, add on the top of your sketch (should be the first line ):

#define BLYNK_DEBUG // Optional, this enables lots of prints
#define BLYNK_PRINT Serial

And enable Serial Output in setup():

Serial.begin(9600);

You can also use spare Hardware serial ports or SoftwareSerial for debug output (you will need an adapter to connect to it with your PC).

WARNING: Enabling Debug mode will slowdown your hardware processing speed up to 10 times!

Blynk.notification("message");

Blynk.email();

In order to use this command, you need to add Email Widget in the App

Send a pre-defined email message

Blynk.email();

Send an email message with custom body:

Blynk.email("Message");

Send an email message with custom body, subject and recipient:

Blynk.email("email@example.com", "Subject", "Message");

#Blynk API. Writing your own library Instructions on how to add support for new hardware

#Security

Blynk server has 3 ports open for different security levels.

• 8441 - SSL/TLS connection for hardware
• 8442 - plain TCP connection for hardware (no security)
• 8443 - mutual authentication (mutual SSL) connection for Mobile Apps

Hardware may select to connect to 8441 or 8442, depending on it's capabilities.

SSL gateway

Most platforms are not capable to handle SSL, so they connect to 8442. However, our gateway script can be used to add SSL security layer to communication.

./blynk-ser.sh -f SSL

This will forward all hardware connections from 8441 port to the server via SSL gateway. You can run this script on your Raspberry Pi, desktop computer, or even directly on your router!

Note: when using your own server, you should overwrite the bundled server.crt certificate, or specify it to the script using --cert switch:

./blynk-ser.sh -f SSL -s <server ip> -p 8441 --cert=<certificate>.crt

Flag "-f SSL" is enabled by default for USB communication so you don't have to explicit declare it. Note: SSL is supported by the gateway only on Linux/OSX for now

If you want to skip SSL, and connect to TCP, you can also do that:

./blynk-ser.sh -t TCP

Local Blynk Server

In order to gain maximum security you could install Blynk server locally and restrict access to your network, so nobody except you could access it. See how to install Blynk server locally here.

Troubleshooting

Connection

If you experience connection problems, follow these steps:

1. Check your wiring using the examples (TCP/HTTP Client or similar) provided with selected shield and hardware. Once you have some understanding how to configure connection, it's much easier to use Blynk.
2. Try running Blynk default examples for your platform without modifications to see if it is working.
   • Read carefully the example comments and explanations
   • Check that your token is valid (copied from the App and doesn't contain spaces, etc.)
   • If it doesn't work, try looking into serial debug prints.
3. Done! Add your modifications and functionality. Enjoy Blynk!

Delay

Your application might be calling a delay() function or sleeps/cycles for a long time inside of the loop(), like this:

void loop()
{
  ...
  delay(1000);
  other_long_operation();
  ...
  Blynk.run();
}

You should be aware that this can degrade performance of Blynk, or cause connection drops.

Note: This also applies to the BLYNK_READ & BLYNK_WRITE handlers!

If you need periodic actions, consider using some timer library, like shown in this example.

Flood

Your application may cause an enormous load on our server, please try avoiding sending data too fast.

For example, in this situation Blynk.run() will quickly finish processing incoming messages, and then new value is sent to the server immediately, causing high traffic:

void loop()
{
  Blynk.virtualWrite(1, value);
  Blynk.run();
}

You might be thinking about adding a delay(), but this creates another trouble.

If you need periodic actions, consider using some timer library, like shown in this example.

Enable debug

To enable debug prints on the default Serial, add on the top of your sketch (should be the first line ):

#define BLYNK_DEBUG // Optional, this enables lots of prints
#define BLYNK_PRINT Serial

And enable serial in setup():

Serial.begin(9600);

You can also use spare Hardware serial ports or SoftwareSerial for debug output (you will need an adapter to connect to it with your PC).

Note: enabling debug mode will slowdown your hardware processing speed up to 10 times.

#Links

• Kickstarter campaign
• Blynk downloads, docs, tutorials
• Blynk community
• Facebook
• Twitter

License

This project is released under The MIT License (MIT)

Other Docs

• Basics
• Widgets
• Security
• Platforms/Connection types
• Troubleshooting
• Implementing your own library