How to connect a Raspberry Pi to Carriots and build an Alert System.

0. Introduction

This easy tutorial helps you to build an Alert System for your home or office.
To do this, we use a Raspberry Pi able to detect light and Carriots Engine to send alerts by SMS.
In this project you will learn how to:

  • Connect a Raspberry Pi to Carriots to send data streams using Carriots HTTP REST API
  • Build an Alert App on Carriots by programming a Listener to send a SMS using the SDK

Difficulty:

Ingredients

  • 1 x Raspberry Pi. An alternative is to use an Arduino Uno
  • 1 x Tiny Breadboard
  • 1 x Resitance. Range between 200KΩ and 10KΩ
  • 1 x Foto Sensor. Try to improve the project with a motion detection sensor
  • 1 x 1uF capacitor. An alternative is to use an Analog-to-Digital Converter chip (ADC)
  • 1 x Case. Optional. Not needed during experiment

Music to listen: Thievery Corporation - Sound the Alarm

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1. Project Schema

This project is a quick way to create an alarm app and understand the basics of combining Raspberry Pi and Carriots.

Here is overall diagram of the project:

  • Schema

Raspbery Pi is programmed to send a data stream to Carriots stating whether or not receiving light

All the data streams sent by Raspberry Pi are collected and stored in Carriots. Carriots is a huge database that collects all the information that your sensors send.

In addition to storing data, the true power of Carriots is to let you build Apps very quickly with few lines of Groovy code. In this scenario we are going to build a very simple Alert App that sends a SMS to you in case that Raspberry Pi detects light.

With Carriots you can build very complex Apps to support all the logic of your product on the cloud and integrate it with other devices and IT systems. But for now let’s keep it simple.

Although this Alert App is very simplistic, you can use to detect someone enters in a dark room and turns on the lights. In fact this project is quite useful in our data-center, where light are always turned off.

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2. Raspberry Pi. Connections description

To read the values ​​of an analog sensor with a GPIO pin, we have relied on the proposed solution in: http://www.raspberrypi-spy.co.uk. If you want to know more about it, please read the following article:
Reading Analogue Sensors With One GPIO Pin

The connections in Raspberry Pi are extremely simple. You can see in the diagram below.

  • Diagram

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3. Carriots Project and Device Registration

Device

If youre registered in Carriots, you have a default device already created for you.
Check your control panel and see what it looks like.
Basically you need the device id_developer that might be something like defaultDevice@myusername.
But if you want, you can create a new device and use it in this example.

Apikey

Now, go to your control panel “My account menu” and check your Apikey.
Its a big alphanumeric token like:
98346673a6377ef1fde2357ebdcb0da582b150b00cabcd5a0d83045425407ab4.
You need this number to complete the example.

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4. Data Transferred from Raspberry Pi to Carriots

From Raspberry Pi you have to build a HTTP request and send the data.

  • HTTP request
    POST /streams HTTP/1.1
    Host: api.carriots.com
    Accept: application/json
    User-Agent: RaspberryPi-Carriots
    Content-Type: application/json
    carriots.apikey: YOUR APIKEY HERE
    Content-Length: YOUR CONTENT LENGTH HERE
    Connection: close
  • Data
    {
    "protocol":"v2",
    "device":"YOUR DEVICEs ID_DEVELOPER HERE",
    "at":1357889146,
    "data":{"light":"YOUR DATA HERE"}
    }

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5. Code implemented on Raspberry Pi

This is the Pythons code to Raspberry Pi. Note that some values should be replaced by your own values.

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6. Checking Data is collected in Carriots

If you get here, your device must be sending streams when you turn on and turn off the lights.

Its time to test our control panel and check if we have new streams.
Go to “Data management” → “Data streams” and you will see your data.

  • menu option
  • new data

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7. Creating an Alert with Carriots Listeners

A listener in Carriots can be associated to any hierarchy entity, from Project to Device. If you associate a listener to a project, all devices below the services of that project will be affected. If you associate a listener to service, all devices below the groups of that services will be affected. And so on.

In this example, we create a listener associated with our device. This listener waits for an event to occur in the context of the device and then evaluate the content.

To create a listener go to the control panel, then to “Rules” → “Listeners” and click on the new button. Select "Device" as "entity type" and select your device on the "Id" field.

Fill the fields with the following values and save the new listener

  • Name: The name that you prefer
  • Description: The description that you prefer
  • Entity type: Device
  • Entity id: Your id device
  • Event to listen: data_persisted
  • If expression:
    context.data.light=="ON"
  • Then expression:
    import com.carriots.sdk.utils.Sms;
    def sms = new Sms ();
    sms.to="YOUR PHONE NUMBER HERE";
    sms.message="Alarm ON";
    sms.send();
  • Then rule: leave empty
  • Else expression:
    import com.carriots.sdk.utils.Sms;
    def sms = new Sms ();
    sms.to="YOUR PHONE NUMBER HERE";
    sms.message="Alarm OFF";
    sms.send();
  • Else rule: leave empty
  • Be sure to have your listener enabled if you want it to be executed

Its time to test our listener. Send a data stream to this device, check your control panel and your phone!!!

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8. From here on: Enhancing the project

Now you know how to connect a Raspberry Pi device to send data to Carriots and how to create a simple App with a single Listener and some SDK programing in Groovy. But you can enhance this project in many ways:

  • Try to add a motion sensor to the Raspberry Pi and send at least two values: light and motion status
  • Create your own control panel to check the status of the Raspberry Pi, by building an HTML page with a request to our API to ask for the status value of your device
  • Create another device that you can interact with (like a sound alarm) and build an app combining actions between the two devices through Carriots
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