Skip to main content

[IoT Home Project] Part 3 - Node.JS Module that reads sensor data

Previous post: http://vunvulearadu.blogspot.ro/2016/12/iot-home-project-part-2-visual-studio.html
GitHub source code: https://github.com/vunvulear/IoTHomeProject/tree/master/nodejs-grovepi-azureiot

In this post we will continue developing the IoT Home Project, by creating a module for Node.JS that reads the sensor data.

Why we create a Node.JS module?
We want to group all the logic that reads sensor data under the same roof. We design the module in a such a way that it will allow us to initialize an instance of an object that can read all sensors data.

GrovePiSensors Module
The module was is called GrovePISensors and expose 5 functions:
  • getSoundData - Gets Sounds data
  • getTempAndHumData - Gets Temp and Humidity data
  • getDistanceData - Get Distance data from Ultrasonic sensor
  • getLightData - Get Light data
  • getAllSensorsData -  Get all sensors data that can be read
The getAllSensorsData returns an object, where all this information are available. The sound information are not collected because it seems that personally I have some problems with the sensor. I'm not able with my board to collect data from sound sensor.

As you can see in the constructor, I have some predefined pins for each sensor. I have the following configuration:
  • DHT Sensor - pin 2  (digital)
  • Ultrasonic Sensor - pin 4 (digital)
  • Light Sensor - pin 2 (analog)
  • Sound Sensor - pin 0 (analog)
, but the constructor allow us to configure the pins as we want. Be careful, not to mix analog with digital pins and sensors. 
By default I log all the information that is read from the sensors in the console, but you can disable this from the constructor if you specify debug to false (default value is true).

From app.js I just initialize the board and read the sensors data. For now, I don't use this.



Lesson learns at this step
  1. I forgot to write an 's' to 'module.exports' and I spent around 2 hours trying to figure our why the module is not working.
  2. There are two types of sensors, digital and analog. If you don't connect them on the right pin, you'll get random data. 
  3. If you are careful you can connect/disconnect sensors while your app is running.
  4. Try to test each sensor after you write the first lines of code that read data from it.
  5. The light sesor show a high value when the light is low. A lower value means that the light level is high.
Next step
Connect to Azure IoT Hub and push this data to cloud.

Next post: [IoT Home Project] Part 4 - Sending temperature data from Raspberry PI to Azure IoT Hub

Comments

Popular posts from this blog

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

Fundamental Books of a Software Engineer (version 2018)

More then six years ago I wrote a blog post about fundamental books that any software engineer (developer) should read. Now it is an excellent time to update this list with new entries.

There are 5 different categories of books, that represent the recommended path. For example, you start with Coding books, after that, you read books about Programming, Design and so on.
There are some books about C++ that I recommend not because you shall know C++, only because the concepts that you can learn from it.

Coding

Writing solid codeCode completeProgramming Pearls, more programming pearls(recommended)[NEW] Introduction to Algorithms

Programming

Refactoring (M. Fowler)Pragmatic ProgrammerClean code[NEW] Software Engineering: A Practitioner's Approach[NEW] The Mythical Man-Month[NEW] The Art of Computer Programming

Design

Applying UML and Patterns (GRASP patterns)C++ coding standards (Sutter, Alexandrescu)The C++ programming language (Stroustrup, Part IV)Object-oriented programming (Peter Coad)P…