AWS Iot Sensors Example

Example of usage of AwS Iot to monitoring a temperature, humidity and motion sensors storing it's data using CloudWatch Metric.

Getting Start

Create Things

Log in to AWS console and simply create some of things like this:

Led

• Name: Led
• Shadow:

{
  "desired": null,
  "reported": {
    "active": 1
  }
}

DHT11

• Name: DHT11
• Shadow:

{
  "desired": null,
  "reported": {
    "temperature": 0,
    "humidity": 0
  }
}

Camera

• Name: Camera

Button

• Name: Button

Motion

• Name: Motion
• Shadow:

{
  "desired": null,
  "reported": {
    "enable": 1,
    "isInAlarm": 1
  }
}

Buzzer

• Name: Buzzer
• Shadow:

{
  "desired": null,
  "reported": {
    "ringing": 1
  }
}

For semplicity create all the things without creating a new certificate for each, then create a single certifiate (using "One-click certificate creation" procedure) and attach it to all things.

Use Security -> Certificates menu to create new one and edit connected things, remember to download all the keys including Amazon Root CA.

Create CloudWatch metrics

For DHT11 sensor that report a temperature and humidity values create a rule named "DHT11" that take as input the sensor's value from the update/accepted topic.

DHT11

• Rule query statement: SELECT * FROM '$aws/things/DHT11/shadow/update/accepted'

In actions section add two actions selecting "Sends message data to CloudWatch", set the values as follow.

Temperature

• Metric name: Temperature
• Metric namespace: Sensor
• Unit None
• Value ${state.reported.temperature}

Humidity

• Metric name: Humidity
• Metric namespace: Sensor
• Unit Percent
• Value ${state.reported.humidity}

attach a new IAM role name with "create" button.

Create SNS Topic

If you want to get notfied when motion alarm is fired you have to create a second rule connected on custom topic motion-acivated.

Motion

• Rule query statement: SELECT * FROM 'motion-acivated'

Then add an action selecting "Send a message as an SNS push notification", create a new SNS topic or attach an existing one, select a raw message format and attach an IAM role.

If you want to receive an email when a message is pushed on that SNS topic, go to SNS service dashboard, select the create topic and then Action -> Subscribe to topic. Select email protocol, insert into enpoint field your email and click on "Create Subscription" button. Now an email will be sent on your email, you have to confirm that subscription simply clicking on the "Confim subscription" link.

Init Project

Clone this repo and install all npm dependencies

npm install

Create a .env file with keys paths (download when you created the certificate) and hostname

HOST=xxxxxxxxxxx.iot.us-east-1.amazonaws.com
PRIVATE_KEY=/path/to/keys/xxxxxxxxx-private.pem.key
CLIENT_CERT=/path/to/keys/xxxxxxxxx-certificate.pem.crt
CA_CERT=/path/to/keys/root-CA.crt
DEBUG=false

Launch it

Exec one of the examples using npm script,

npm run dht11

Every second the example generate a random value for temperature and humidity value and push it on AWS IoT.

npm run motion

Every second the example generate a predefined state (0,0,0,1,0,0,0,1) and you'll receive the notification when the status become 1 from 0.

npm run camera

This example simulate a button to take a photo from the camera when clicked

npm run led

When remotly you change the desired state of led sensor this example notify the change.

Show Metric

Go to CloudWatch and select the custom metric create "Sensor/Temperature" or "Sensor/Humidity"

Code Specs

Inside lib directory you will find a thing.js file that describe Thing class, core of the example. In devices directory there are the device's file with the custom class that extends Thing class with setters method.

When the specific property is update it trigger AWS IoT SDK to push the new data

motion.isInAlarm = 0;

From the inside of device's class you can push message on custom topic

this.send("motion-acivated");

Get message from the topic when sended

this.on("motion-acivated", function(message){
  // do stuff
})

Listen from remote state changes

this.onChange(function(state){
  if(state.active == 0){
    //do stuff
  }else{
    //do other stuff
  }
})

Debug

To enable client side debug set to true the debug variable in .env file

DEBUG=true

To enable debug on AWS side enable logging in Settings -> CloudWatch Logs to create a stream with the selected level on debugging.

Install gpio utility on RaspberryPI

sudo apt install -y wiringpi

PM2

Using PM2 process manager you can use the pm2.config.js file as configuration

pm2 start ./pm2.config.js

the save the current configuration

pm2 save

and set the process starting on system startup

pm2 startup

Process are now up and running

RaspberryPI configuration

Electronic Schema

Set GPIO port of the sensors

GPIO_BUTTON=27
GPIO_BUZZER=23
GPIO_DHT11=18
GPIO_LED=17
GPIO_MOTION=22

Install library for DHT11 sensor

cd /tmp/
wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.52.tar.gz
tar zxvf bcm2835-1.52.tar.gz
rm zxvf bcm2835-1.52.tar.gz
cd bcm2835-1.52
./configure
make
sudo make install
cd ..
rm -rf bcm2835-1.52

Install NodeJS, npm and git

sudo apt install nodejs nodejs-legacy npm git

Clone this repo from the inside of RaspberryPI

git clone https://github.com/daaru00/aws-iot-example.git
cd aws-iot-example

Install all npm dependencies

npm install

Install the additional node-dht-sensor module

npm install node-dht-sensor