There are many ways of remotely-controlling your Arduino or compatible hardware over the Internet. Some are more complex than others, which can be a good thing or a bad thing depending on your level of expertise. Lately we’ve become more interested in this topic and have come across Blynk, which appeared to be a simple solution – and thus the topic of our review.
What is Blynk?
From their website: “Blynk is a Platform with iOS and Android apps to control Arduino, Raspberry Pi and the likes over the Internet. It’s a digital dashboard where you can build a graphic interface for your project by simply dragging and dropping widgets.
It’s really simple to set everything up and you’ll start tinkering in less than 5 mins. Blynk is not tied to some specific board or shield. Instead, it’s supporting hardware of your choice. Whether your Arduino or Raspberry Pi is linked to the Internet over Wi-Fi, Ethernet or this new ESP8266 chip, Blynk will get you online and ready for the Internet Of Your Things.” Here is the original launch video:
Blynk started off as an idea, and raised initial funding through Kickstarter – which was successful and the system has now launched. Blynk comprises of an app on your smartphone (Android or iOS) inside which you can add widgets (controls) to send commands back to your development board (Arduino etc.).
For example, you can add a switch to turn a digital output on or off. Furthermore, data from sensors connected to the development board can be send back to the smartphone. The data passes through the Blynk Cloud server, or you can download and run your own server on your own hardware and infrastructure.
How much does it cost?
Right now (September 2015) the Blynk system is free. We downloaded the app and experimented without charge. We believe that over time there will be payment required for various functions, however you can try it out now to see if Blynk suits your needs then run with it later or experiment with other platforms.
You can also use other Arduino+Ethernet combinations, such as an Arduino Uno with an Ethernet shield. First you need to download the app for your phone – click here for the links. Then from the same page, download the Arduino library – and install it like you would any other Arduino library.
For our first example, we’ll use an LED connected to digital pin 7 (via a 560 ohm resistor) shown above. Now it’s time to set up the Blynk app. When you run the app for the first time, you need to sign in – so enter an email address and password:
Then click the “+” at the top-right of the display to create a new project, and you should see the following screen:
You can name your project, select the target hardware (Arduino Uno) – then click “E-mail” to send that auth token to yourself – you will need it in a moment. Then click “Create” to enter the main app design screen. Next, press “+” again to get the “Widget Box” menu as shown below, then press “Button”:
This will place a simple button on your screen:
Press the button to open its’ settings menu:
From this screen you can name your button, and also determine whether it will be “momentary” (i.e., only on when you press the button) – or operate as a switch (push on… push off…). Furthermore you need to select which physical Arduino pin the button will control – so press “PIN”, which brings up the scrolling menu as shown below:
We set ours to D7 then pressed “Continue”. Now the app is complete. Now head back to your computer, open the Arduino IDE, and load the “Arduino_Ethernet” sketch included with the library:
Then scroll down to line 30 and enter the auth key that was sent to you via email:
Save then upload the sketch to your Arduino. Now head back to your smartphone, and click the “Play” (looks like a triangle pointing right) button. After a moment the app will connect to the Blynk server… the Arduino will also be connected to the server – and you can press the button on the screen to control the LED.
And that’s it – remote control really is that easy. We’ve run through the process in the following short video:
Now what else can we control? How about some IKEA LED strips from our last article. Easy… that consisted of three digital outputs, with PWM. The app resembles the following:
… and watch the video below to see it in action:
Monitoring data from an Arduino via Blynk
Data can also travel in the other direction – from your Arduino over the Internet to your smartphone. At the time of writing this (September 2015) you can monitor the status of analogue and digital pins, and widgets can be added in the app to do just that. They can display the value returned from each ADC, which falls between zero and 1023 – and display the values in various forms – for example:
The bandwidth required for this is just under 2 K/s, as you can see from the top of the image above. You can see this in action through the video below:
We have only scratched the surface of what is possible with Blynk – which is an impressive, approachable and usable “Internet of Things” platform. Considering that you can get an inexpensive Android smartphone or tablet for under AU$50, the overall cost of using Blynk is excellent and well worth consideration, even just to test out the “Internet of Things” buzz yourself. So to get started head over to the Blynk site.