Make a Simple Raspberry Pi Weather Dashboard Using IBM Cloud

Navigate to this repo: https://bit.ly/2rOwaGK

Introduction

Node-RED is a wonderful tool that is used for prototyping and interacting with IoT devices, like the Raspberry Pi. It is a tool that is very easy to get started with and is a great for beginners who want to write and understand programming flow.

In this lab we will be using Node-RED on IBM Cloud to build a temperature and humidity dashboard. We will receIve temperature and humidity data from a Raspberry-Pi Sense hat and then use this data to create a dynamic real time dashboard that provides information about humidity and temprature metrics that the SenseHat provides.

In this workshop you will learn :

(1) The fundamentals of Node-RED and IBM Cloud

Learn More

Node-RED is a visual tool for wiring the Internet of Things. It is easy to connect devices, data and API’s (services). It can also be used for other types of applications to quickly assemble flows of services.

Node-RED is available as open source and has been implemented bythe IBM Emerging Technology organization. Node-RED provides a browser-based flow editor that makes it easy to wire together flows using the wide range of nodes in the palette. Flows can be then deployed to the runtime in a single-click. While Node-Red is based on Node.js, JavaScript functions can be created within the editor using a rich text editor. A built-in library allows you to save useful functions, templates or flows for re-use.

Node-RED is included in the Node-RED starter application in IBM Cloud but you can also deploy it as a stand alone Node.js application. Node-RED can not only be used for IoT applications, but it is a generic event-processing engine. For example, you can use it to listen to events from http, websockets, tcp, Twitter and more and store this data in databases without having to program much if at all. You can also use it for example to implement simple REST APIs. You can find many other sample flows on the Node-RED website.

(2) The fundamentals of working with the Raspberry-Pi Sense Hat

Learn More

The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. It’s capable of doing everything you’d expect a desktop computer to do, from browsing the internet and playing high-definition video, to making spreadsheets, word-processing, and playing games.

In this lab we will be working with the Raspberry Pi as well as an accessory called the Sense HAT Cape

The Sense HAT is an add-on board for the Raspberry Pi, made especially for the Astro Pi competition. The board allows you to make measurements of temperature, humidity, pressure, and orientation, and to output information using its built-in LED matrix.

In this lab we will be using the Rasberry Pi and the Sense HAT to capture data on Temperature and Humidity which will then be displayed on a dashboard built on Node-RED on the IBM Cloud

Prerequisite : Create IBM Cloud Account

In order to complete this workshop you will need to create an IBM Cloud account.

1. Sign up for an account here

2. Verify your account by clicking on the link in the email sent to you

Hardware Setup :

The Raspberry Pi with the Sense HAT allows you to make measurements of temperature, humidity, pressure, and orientation, and to output information using its built-in LED matrix. We will use it to publish Temperature(Centigrade) and Humidity metrics to Node-RED on the IBM Cloud - free account! It will also display the Temperature(Centigrade) to the matrix screen everytime your cron job runs

Step 1 :

• Setting up Raspbian on your Pi is easiest with NOOBS

Step 2 :

• setting up Sense HAT

Step 3 :

• Open or ssh into your pi, then setup a cron job as root on Raspberry Pi with a SenseHat

#become root user
sudo su
touch /home/pi/sense.log
crontab -e
# add the following line to POST updates every 5 or any interval you like, I chose 5 minutes
echo "5 * * * * /usr/bin/python /home/pi/dev/pi-hat-node-red/push.py >> /home/pi/sense.log 2>&1"
# restart cron
systemctl restart cron

exit
#revert to pi user
mkdir -p /home/pi/dev && cd /home/pi/dev

#clone repo
git clone https://github.com/IBMDeveloperNYC/Pi-Sense-HAT-Node-RED
cd Pi-Sense-HAT-Node-RED
ls
stat push.py
echo "push.py should be here"

Node-RED Setup

Once your hardware is set up , the next thing we are going to do is set up Node-RED on IBM Cloud. We will then use the Node-RED editor to create a flow to read the data coming from the Raspberry-Pi and the Sense HAT and display the data on a dashboard that looks like so :

STEP 1 : Run Node-RED using IBM Cloud

1. Log in to your IBM Cloud account
2. Click on "Catalog" at the top-right corner
3. Search and select "Node-RED Starter"
4. Give name to your app and click "Create" --> We Suggest <<lowercase_firstinitial>><<lowercase_lastinitial>>nodered

   User Name - James Bond 
   Node-RED App Name  - jbnodered

5. Once your app is created you'll be able to access it through the resource list

Click the 'Visit App URL' option to access your Node-RED instance in your browser. (click next for the steps displayed until you see the option 'Go to your Node-Red Flow Editor', and select "Not recommended: Allow anyone to access the editor and make changes" for the second step.

STEP 2 : Working with the http input node

In the left navigation pane of the Editor you will see a lot of standard Node-RED nodes.

1. From the input category of nodes drag the http node and drop it on the editor pane.

Single clicking on a dragged node lets you see the info for the node on the 'Info' tab on the right navigation pane. Double clicking on the node lets you edit the node's properties.

2. Double click on the http node to edit it's properties

• Set Method to Post
• Set url endpoint to /sense-hat
• Set name to Sense-HAT POST

You should have this :

STEP 3: Connect http input to http output

1. From the output category of nodes , drag the http-response node into the editor.
2. Drag a connection from the http input node and connect it with the http output node
3. Double click on the output node and set:

• Status Code -> 200
• Add headers by clicking on the + add button on the bottom
• Name the header key : done and header value : OK-MRB

4. You can also drag a debug node and connect it to the output of the input node to see the response once we connect the url to the raspberry pi

Double click on debug node and set output to complete msg object

You should have this :

Basically what we are trying to do here is create a connection for the Raspberry Pi to send messages to. The way we can do this is by creating a POST request

To test if the Raspberry Pi is successfully able to recieve messages from the PI :

Take the url for your NodeRED instance and append the /sense-hat

You should have something like this :

https://<<lowercase_firstinitial>><<lowercase_lastinitial>>nodered.mybluemix.net/sense-hat

<> is the name you gave your Node-RED instance. It can be found in the url of your Node-RED editor

This is the url that we will then add to the push.py code which is used to capture the temperature and humidity data from the Sense HAT

Once successfully connected you should be able to see the temperature and humidity in the debug panel.

Congrats if you are able to see data in your debug panel! You can now move on to building a dashboard from this data!

* If you can not see data coming in from PI you can build a DATA Simulator *

1. From the input category of nodes drag the input node and drop it on the editor pane.
2. Double click on the input node to edit it's properties

• Set Payload to JSON
• Copy JSON from tempData.json and paste it into JSON input

this will act as the JSON temperature and humidity data coming from the pi

• Name node Sense-HAT Simulator

3. Connect the Sense-HAT Simulator node to debug node and deploy

Double click on debug node and set output to complete msg object

Now when you click on the inject button you should see the data that the sense hat would simulate.

Congrats!You can now move on to building a dashboard from this data!

STEP 4: Building the Temparature and Humidity Function

In this step we will have to do some math to convert the temperature and humidity coming from the PI to Farenheit and Celcius. The output from this function will include :

• Humidity
• Temperature - Farenheit
• Temperature - Celcuius

1. From the function category of nodes , drag the function node into the pannel.
2. Double click on the function node and add the following code :

if( msg.payload === false ) {
    return null;
}
    
var msg1 = {};
var msg2 = {};
var msg3 = {};

msg1.payload = Math.round(msg.payload.temp*1.00);
msg1.topic = "Centigrade";
msg2.payload = Math.round(((msg.payload.temp*1.00) * 9/5) + 32);
msg2.topic = "Farenheit";
msg3.payload = Math.round(msg.payload.humidity*1.00);
msg3.topic = "Humidity";

return [msg1, msg2, msg3];

This code is outputing 3 messages from 3 variables msg1 = Celcius , msg2 = Farenheit , msg3 = Humidity

3. Make sure the output of the function is 3 since the code is outputting 3 values that we will use to build our dashboard
4. Name the function temp and humidity preparation

Your function properties should look like this :

5. Once you have the function node setup you will want to connect it's outputs to debug nodes.

• Drag 3 Debug nodes to the editor and connect the nodes to the output of the function
• Name the Debugs as Centigrade , Farenfeit and Humidity

3 function variables : msg1 = Celcius , msg2 = Farenheit , msg3 = Humidity You should have something that looks like this :

Step 5 : Adding Function Inputs

Your input to the function node will depend on wheather you connect to the POST request nodes that connect to the Raspberry Pi and Sense Hat or if you connect to the Sense-HAT Simulator node your

Connecting to POST request nodes

This method assumes that you will send your Node-RED url and endpoint to the push.py code to recieve live updates from the Raspberry Pi and Sense Hat

• Connect the output of the http input node named sense-hat POST to the input of the function node You should see something like :

Now on your debug pannel you should see the Farenheit , Centigrade and Humidity that is coming in live from the Raspberry-PI and Sense-HAT

Congrats! You are seeing real-live temerature and humidty data coming into the cloud from IoT device!

Connecting to the Sense-HAT Simulator node

This method assumes that you will be using an input node with sample JSON to simulate the IoT Device

• Connect the output of the inject input node named SenseHat Simulator to the input of the function node

Your flow should look like this. Once you deploy, you can inject the value from the input node. You should be able to see the Farenheit , Centigrade and Humidity that is simulated in your debug panel

Congrats! You are seeing temerature and humidty data that is simulated from an IoT device! Feel free to change values on of humidity and temperature in the tempData.json input to see how the function converts temperature to Celcius and Farienheit.

Step 6 : Creating Dashboard

If you don't have dashboard nodes you will need to install them. To do so go to:

• The hamburger menu on the top right hand side of your node-RED editor.
• Go to Manage Palette
• Go to Install Tab and search for node-red-dashboard
• Press install and shortly you will see dashboard nodes in your right hand node palette

Steps to Create a Dashboard

1. From the dashboard category of nodes , drag three guage nodes into the pannel.
2. Connect each guage node to the three outputs of the function nodes

Similar to the debug nodes in the previous stes

3. Edit Guage Nodes :

• Double click on the properties of 1 of the Guage Nodes
• Edit Group by clicking on the pencil icon
  • Give a Name such as Sense Hat Simulator
  • Give a Tab name by clicking on pencil next to Tab Value . I called mine SenseHAT-Dashboard
  • Click Update and you should see :

This will be the Dashboard Name that will be used across all guage nodes in this flow

4. Give the Guage a lable such as : Centigrade
5. Give the Guage a value range : 0 to 100
6. Repeate these steps for the two other Guage Nodes , except give the other two guages Farenheit and Humidity labels

You should see something like this : POST Node Connection Flow

Simulator Connection Flow

Now if you go to the Dashboard tab on the right hand side next to the debug and info tabs you should be able to launch your dashboard. Click on the little square with arrow in the right most corner to see Dashboard!

Congratulations for completing this Lab!

Congrats for completing this lab. By the end of this lab you should be able to see how you can tie in Hardware IoT device such as a Sense-HAT Cape with a Raspberry Pi to send temperature and humidity data to Node-RED on the IBM Cloud

If you ever get stuck on any of these steps go ahead an import any of these solutions into your Node-RED editor.

To Import Go to > Hamburger Menu > Imort > Clipboard

You can copy the JSON contents of either of these flows to see how the solutions were created in the steps above!

• POST request Sense-HAT Flow
• Sense-HAT Simulator Flow

Appendix/Figures/Images

Figure 1: Node-RED Guages indicate it's Cold indoors

Figure 2: Node-RED Guages indicate it's Warm indoors

Figure 3: Node-RED Guages indicate it's Very Hot indoors

Figure 4: SenseHAT mounted on Raspberry Pi 3 using plexiglass housing with brass spacers