Introduction: LinkIt One - Blynk - Temperature Guage

In this instructable I'm going to show you how to create a temperature Gauge device so you can plot the temperature using the Blynk app on any android or iPhone device. In my previous project I should you how to control any digital pin using the Blynk app and also control an LED using the Blynk app. Make sure you try out my previous project before you try this.

For those who do not know the Blynk app is an android or iPhone app which can be used to control and monitor any IoT device like the Arduino, LinkIt One, Particle core, etc. The app provides a wide rage of features which makes programming an IoT device more interactive.

Step 1: Tools and Components

So lets start with gathering all the components and tools required for this project. Most of the components come along the linkit one box, like battery and WiFi antenna. So here is what you need -

  • LinkIt One
  • Breadboard
  • LM35 Temperature sensor
  • Battery
  • Android or a IPhone
  • Micro USB Cable

Step 2: Circuit

The circuit is really simple and we will be using an LM35 IC. The Circuit is really simple all you do is connect the -

  • LM35 VCC to LinkIt One +5v
  • LM35 signal to LinkIt One analogue pin 5
  • LM35 GND to LinkIt One GND

After connecting the circuit on a breadboard now its time to run a test sketch.

Step 3: Test Sketch

Before connecting to the Blynk app lets check the LM35 to get temperature readings in degree Celsius. Upload the code below in the suitable com port and open a serial monitor once the code is been uploaded. You should see a stream of temperatures being displayed on the terminal. If you encounter any problem try checking the connections or feel free to leave a comment below and I would be glad to help you.

float tempC;
int reading; int tempPin = 0; void setup() { Serial.begin(9600); } void loop() { reading = analogRead(tempPin); tempC = reading / 9.31; Serial.println(tempC); delay(1000); }

Step 4: Code

Once you have the test code running it is time to complete the project and upload the code for the Blynk app. The code can be found below make sure you install the Blynk library from the official blynk website, before you compile the code. Make sure you enter the access token, SSID, password before uploading the code to the board. The access token is available in the app once you create a new project.

Step 5: Blynk App

The Blynk app can be found on the android play store or the apple store if you are using an IPhone. Install the app and create a free account. Once you have created your account you can create a new app select the linkit one board from the list of boards and you would get an access token.

You need to enter this access token in the code in the previous step. Now you need to add a gauge element and set it to read from virtual pin 10, then power on the LinkIt One and you should see the temperatures values being streamed to the app every few seconds.