As technology around us is continually evolving, we often come across the term, ‘Internet of things’. It is a resolutionary technology and is anticipated to be on top of the technological  world in the upcoming years. One such important technology which is a part of the iOT is  the Raspberry pi-Processor which plays a major role  for prototyping a project model, and  job easy as it supports python and other cool features .To learn more about all that Raspberry does, you can click here. In the following article, we would basically learn ‘How to make  communication with gcloud-IoT core using its MQTT protocol’. 

Prerequisite:

  • Raspberry pi3
  • Micro SD Card -8GB+
  • Micro SD card reader
  • Keyboard
  • Mouse
  • Monitor with HDMI port
  • DHT22 sensor
  • Jumper wires and breadboard
  • Python 3+
  • Raspbian OS for Raspberry pi
  • gcloud account. Along with gcloud-IoT core and Pub/sub API

Raspberry pi set up for MQTT communication:

Before undertaking the following steps, you have to complete basic setup for Raspberry:

Step1:

Initially, we have to update the libraries existing in the Raspberry pi to deter the future issues. For that run the following command: 

   sudo apt-get update $$ sudo apt-get upgrade

Step 2:

Install JWT for the secure connection with IoT core. Security threat is one of the core factors that needs to be considered while undertaking any process in IoT. Authentication is done by JSON Web Token, gcloud-IoT core handles by pyjwt it’s based on the python library called  cryptography. Before installing the pyjwt , install the following required  libraries to support pyjwt by running this command.

Important pointers to remember: Ensure that you have python 3.x as gcloud released new major version of python client libraries won’t support Python 2.x

   sudo apt-get install build-essential

   sudo apt-get install libssl-dev

   sudo apt-get install python-dev

   sudo apt-get install libffi-dev

Step 3:

Install the pyjwt by running the following command:

sudo pip3 install pyjwt

Step 4:

To run the pyjwt we need cryptography. For installing the same, you would need to run the following command:

sudo pip3 install cryptography

Step 5: Clone the gcloud-community tutorials by following the below command

git clone https://github.com/GoogleCloudPlatform/community.git

Go to the directory of cloud-iot-gateways-rpi 

  cd community/tutorials/cloud-iot-gateways-rpi

Step 5:

If you are working on a different python project you can separate their dependencies one from another  by creating a virtual environment. Run the following command to install the virtual environment.

  pip3 install virtualenv

  virtualenv env

  source env/bin/activate

Step 6:

 Run the following command to install the python libraries where in the  directory of requirement.txt file

 sudo pip3 install -r requirement.txt

gcloud setup and configuration:

Enable the following API’s 

Cloud IoT core

Cloud IoT Core for managing devices and gateways. 

Cloud Pub/sub

Cloud Pub/Sub for  managing the device telemetry. 

Create Registry:

Before creating the registry, you need to create project in gcloudPlease follow the link for doing the initial setup

Create a registry:

Create your registry in IoT core section as shown in the below screenshot, While you create registry keep in mind few things such as:

Region:

It should be your nearest region in our case which is asia-east1 and then select protocol is MQTT or both based on your requirement. Here we are going to make a communication between device so MQTT protocol is more convenient

gcloud supports both MQTT and HTTP

On stack driver logging choose your device logging which you wish to store

Create registry page

Gateway Setup in gcloud :

Step1:

Clone the Google cloud tutorials code from the git by running the following command

We can use Raspberry pi or your computer as a gateway for the gateway setup process, Here we are using JWT for authentication, for getting the JWT authentication needed to generate Private and public key pairs.

Clone the repository from the Google Cloud community for initial setup for gateway 

 Git clone https://github.com/GoogleCloudPlatform/community.git

Go to the directory of cloud-iot-gateways-rpi 

 Cd community/tutorials/cloud-iot-gateways-rpi

Step 2:

Generate the public and private key pair by running the following command

 ./generate_keys.sh

Step3: Go to the registry tab, click on gateway 

Step4: Enter gateway id

Step 5: Allow Gateway communication

Step 6: Add public key by manually or upload

Step 7: Select the public key format in our case which is RS256_X509

Step8: Click on create button and let other as it is 

Step 9: Modify the run-gateway by the arguments which you provide while you create such as , registry_id and device_id and so on

Step 10: Generate the root certificate by running the following command

gateway credentials

Wget https://pki.goog./roots.pem

You can create virtual environment in gcloud-IoT core to seperate your projects from your other cloud projects, Follow the below command

     pip3 install virtualenv

     virtualenv env

     source env/bin/activate

Step 11: Install the requirements-gateway.txt by running the following command.Ensure that you are in the directory of the file is requirements-gateway 

pip3 install -r requirements-gateway.txt

Step 12: Run the  gateway code with your modified arguments by following the command

source run-gateway

Device Configuration and creation:

Create your device in the IoT core section as mentioned in the below screenshot.

crt-device creaton

The next step is ,we need to bind our devices with gateway, create your gateway in the gateway tab as mentioned in the below screenshot. While you create gateway, you may get an error alert saying “invalid key format” ,change it to other format in our case which is:
RS256_X509

GATEWAYY-CRT

Device configuration with Raspberry pi to talk with gcloud-IoT core:

Go to the device tab, click on the device that you created, click on update configuration and provide the details as shown in the screenshot below.

update configuration

Publish and subscribe data on Google Cloud and your gateway device:

Publish and subscribe(Pub/sub) is a MQTT protocol, it sends the data like a message bus.

Get the IP address of your gateway using ipconfig(windows) or ifconfig (Raspberry pi) for setting up your publish client.

Publish your telemetry data from your gateway

Step 1: Enter your ip address in thermostat.py 

Step 2: Make your hardware configuration with  raspberry pi

Step 3: To ensure the gateway is running in your raspberry by follow the below command

source run-thermostat

Step 4: You can see your data in your terminal which published to the MQTT broker after running the above command

Create subscription and subscribe telemetry data on gcloud:

Create Subscription:

 Search pub/sub in the search box and create a subscription by giving required parameters as mentioned in the screenshot. Here you would need to select the pubsub topic which you created earlier, delivery type is “Pull” as we getting the data from our gateway device (Raspberry pi)   

crt sunscription     

open the gcloud shell terminal and run the following

gcloud pubsub subscriptions pull My subscription –auto-ack –limit=100

Finally you would be able to  can see the data subscribed from the device in gcloud shell terminal if everything is done.

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