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IoT Cricket Khairul Alam – making the Internet of Things accessible for everyone Part 2: Working with Node-RED and Raspberry Pi I n this issue, we will show how you can easily start to build the first parts of a local home automation system. We will make a battery-powered Wi-Fi sensor with an IoT Cricket module and integrate it with Node-RED – without writing code or programming. We will use the popular low-price Raspberry Pi (RPi) to host Node-RED in our local network. If you don’t have an RPi, you can use FRED (https://fred.sensetecnic. com/) a cloud-based Node-RED server without subscription costs. Last time, in Part 1 (PE, June 2021) we showed how to use Cricket to make an IoT sensor node without any programming and integrate it with ThingSpeak for real-time visualisation of sensor data. ThingSpeak is a powerful tool for showing and analysing data, but for automation systems we need a more generic core system for data processing and integration to other systems. This is where NodeRED comes into play. Node-RED The aim this month is to expand our capabilities by setting up the chassis of a local home automation system using Node-RED, explaining how Node-RED is used as we progress. We are going to replicate what we achieved with ThingSpeak in Part 1, which will set us up for more advanced projects in the future. This project can be realised by makers at all skill levels. It may require some basic soldering, but it doesn’t require any coding or programming. By the end of this project you’ll have a solid understanding of how you can build your own local system and extend it by adding your own IoT end nodes. Our system is going to be based on the MQTT communication protocol, which has been widely adopted in most Md. Khairul Alam is an Assistant Professor at the University of Asia Pacific, Dhaka, Bangladesh. He is an independent Cricket developer and does not work for Things On Edge. 58 IoT sensor nodes and home automation systems. We discussed MQTT protocol in detail in Part 1, so please refer to the June issue if you missed it. We will set up our own local MQTT broker for this project by installing an open-source Mosquitto MQTT broker on our RPi. Using a local broker gives us full control of the system without relying on the Internet. Prerequisites You will need the following hardware:  RPi with Raspbian OS installed (we used ver. 3 but others should work)  IoT Cricket Wi-Fi module  2 × AAA battery holder  2 × AAA batteries. What is Node-RED? Node-RED is a free and open-source graphical programming tool, primarily designed for the Internet of Things. It allows programmers of any level to interconnect physical things, cloud-based systems, databases and APIs to build applications using a web interface. It’s great advantage is that it requires very little, if any, programming knowledge. With Node-RED we can easily design our own automation system(s) by dragging and dropping nodes and connecting them. As the data flows through the system of connected nodes it triggers and performs actions defined by each node. One can compare Node-RED to a water system with various type of nodes, such as valves, power generators, heaters/coolers, pumps, tanks, outlets and so on. As the water flows it activates system nodes to use/modify (decision making) the water and generate the desired output(s) of the system. For Node-RED, the ‘water’ is your data. As the data flows through the system, it passes in sequence from one connected node to another. Each node acts on the data and performs some actions and then passes it on. There are many types of nodes available which, for example, allow data to be:  Filtered  Visualised on custom dashboards  Stored in database/filesystem  Sent as notifications – eg, email or Twitter. We also have many choices around integrating the data flow with other software and Internet services. Plus, a big advantage of Node-RED is that we can set up a system in our local network without relying on Internet service providers. Node-RED allows developers to connect nodes (ie, predefined code blocks) to perform a task. The connected nodes – usually a combination of input nodes, processing nodes and output nodes – are ‘wired’ together to make up an application program called a ‘flow’. There are lots of nodes available to perform simple and complex tasks, including web access, Twitter posting, email, HTTP, UDP, MQTT, control of GPIO ports, displaying a graphical dashboard and more. Also, many builtin nodes allow you to install third-party nodes, just like we install third-party libraries in Arduino. Note that although we will focus on the graphical nature of Node-RED, it allows you a lot of functional control (similar to custom functions in a text language) through JavaScript. JavaScript is the programming language that is underlying Node-RED. That’s enough background to NodeRED. Now let’s learn how we can use it to make our own system; and the best way to learn is by doing it ourselves. There are plenty of resources available on the Internet (Google, of course, is your friend here). However, this month’s project will provide a basic introduction of how to set it up on an RPi and integrate devices built with the Cricket IoT Wi-Fi module into your system. Installing Node-RED on Raspberry Pi Before starting, I am assuming you have access to an RPi with the Raspbian OS installed and already have some experience working with it. If you have yet to install the OS then you can find Practical Electronics | October | 2021 Now, you can open the Node-RED web editor by going to the following URL in your favourite web browser from any computer/phone connected to the same network as the RPi: http://{your_pi_ip-address}:1880 Fig.1. Installing ‘build-essential’ before installing Node-RED on the RPi. Fig.2. Part of the terminal output when Node-RED starts in RPi. detailed instructions on installing the operating system image on RPi here: https://bit.ly/pe-oct21-iot1 You can find the most up-to-date official instructions on installing Node-RED on RPi here: https://bit.ly/pe-oct21-iot2 Note that if you downloaded and installed the latest RPi OS then it’s possible Node-RED is already preinstalled. You can check this at the terminal with the command: node-red --help Before we start installing, it’s good practice first to update the system components using the following terminal commands: sudo apt-get update sudo apt-get upgrade To obtain the IP address of your RPi use this command: hostname -I If everything works correctly, you should now be greeted by the screen shown in Fig.3. It would be convenient to have Node-RED running permanently as a service in the background so that whenever we start our RPi the Node-RED system automatically launches at boot time. All we need to do this is execute the following command: node-red-start The above command starts the Node-RED service and displays its log output. Pressing Ctrl-C or closing the window does not stop the service; it keeps running in the background. Now enable the service to autostart by running the command: sudo s0ystemctl enable nodered.service Then, run the following command to install ‘build-essential’: sudo apt install build-essential Fig.3. View of the Node-RED workspace. Note that you may get the result shown in That’s it. Now, whenever we boot RPi the Node-RED service Fig.1 if it’s already the newest version. After that, install Nodewill automatically start. RED by running the following command in the terminal. This command will download and run a script provided by Node-RED authority to install Node.js, npm and Node-RED onto an RPi. Getting started with Node-RED bash <(curl -sL https://raw.githubusercontent. Now that we have Node-RED up and running com/node-red/linux-installers/master/deb/ on our RPi, let’s start with a very simple update-nodejs-and-nodered) example before going on to our main project. As we’ve already discussed, a program The ‘npm’ stand for ‘node package manager’ and is useful for created in Node-RED is called a ‘flow’, the JavaScript programming language that Node-RED is built and it’s created by wiring multiple nodes on. npm will enable you to install additional modules for use together. There are three main types of nodes: with Node-RED. Before the script begins to run you will be 1. Input nodes (eg, inject) Fig.4. The three asked two questions. Just type ‘y’ and press ENTER for both 2. Processing nodes (eg, function) basic nodes. to continue. 3. Output nodes (eg, debug). After installing Node-RED you need to start it. There are different ways to do this, but the easiest is to run the following Three example nodes are shown in Fig.4. Input nodes allow command, which will produce the terminal output shown in you to input data into a Node-RED program or flow. They have Fig.2: node-red at least one output endpoint represented by a small grey square This works fine on an RPi with at least 2GB of RAM. For on their right side. Output nodes are used to send data outside earlier RPi models with limited RAM, it’s better to specify the and have a single endpoint on their right side. Processing nodes amount of RAM, as follows: allow us to process data. They have an input endpoint and one node-red-pi --max-old-space-size=256 or more output endpoints. In a Node-RED flow, messages pass between nodes, moving from input nodes, through processing Regardless of which method you choose, the Node-RED service nodes to output nodes. will begin within a few seconds, and indicate that it is running Let’s build a ‘Hello World’ type of flow to see how simple it is on ‘localhost’ with the default port 1880. to use the Node-RED UI to build and deploy (run) flows. (Note Practical Electronics | October | 2021 59 Fig.5. Three parts of Node-RED environment. Fig.6. The Hello World flow. that in this case we won’t actually print out the words ‘Hello World’ – we will say ‘hello’ by printing a timestamp.) To do this we will use an inject node to input a timestamp into the flow, which is consecutively wired to a debug node for printing out the timestamp on the screen. Since this is our first flow build, we’ll explain each step with a screenshot. Our first node will be the inject node. This is used to generate input for Fig.7. Deploying the flow. our flow. Drag and drop an inject node (from the node palette on the left) into the flow workspace (centre), and then look at the info tab (on the right) where you’ll see the attributes of the node. Fig.5 shows the node palette, workspace with added inject node and debug palette. In the workspace inject node you can see a timestamp because by default a timestamp input is set – the current time in milliseconds since 1 January 1970. You will see a small grey square on the right side of the node where we attach a wire that routes an output message to the next node in the flow. To sense the output from the inject node let’s add a debug node by dragging one from the node palette to the workspace. There are now two nodes in the workspace and we need to wire these together. To do that, click on the grey output point for the inject node, holding the mouse button down, drag towards the debug node. An orange wire appears, which you can then attach to the grey input point on the debug node. The complete flow will look like Fig.6. After building the ‘Hello World’ flow we need to ‘deploy’ it to see the output. Click the Deploy button (top right) and you will see a pop-up saying the flow has been successfully deployed (see Fig.7). Now click on the left tab on the inject node and you will see the timestamp (a long number) appear in the debug pane on the right-hand side (see Fig.8). Congratulation, you created and deployed your first flow, and we are ready to move on to the next step. Our goal is to receive the temperature and battery level from the Cricket using MQTT communication protocol and display the data on a graphical web dashboard. Node-RED will be used to receive MQTT data, make a graphical dashboard and display the result in real time. Let’s take this in stages. MQTT in brief Fig.8. Output of the flow. MQTT is a lightweight messaging protocol designed for resource-constrained devices with low bandwidth. MQTT consists of a message broker and a number of clients. The broker is a server that receives all messages from the clients and then routes those messages to relevant destination clients. A client is anything that can interact with the broker to send and receive messages using a specific topic. Every MQTT broker (local or cloud) has a host address and a port number, which is 1883 for non-encrypted communication. Clients connected to the same broker can communicate with each other. To know more about MQTT please refer to page 44 of the June issue. In this project we are going to set up our own local MQTT broker on our RPi running Node-RED. Installing an MQTT broker on Raspberry Pi First, with Node-RED running, we will install the open-source Mosquitto MQTT broker on our RPi. Mosquitto is lightweight and is suitable for use on all devices from low-power, single-board computers to full servers. To Install Mosquitto broker, open a terminal and type the following command: sudo apt-get install mosquitto -y Fig.9. Editing the RPi config file. 60 To configure Mosquitto broker open the config file using a text editor (eg, nano or vi): Practical Electronics | October | 2021 Finally, restart RPi to apply changes: sudo reboot That’s it! Our MQTT broker is up and running now. You can test the installation with the command: mosquitto -v Fig.10. Configuration of the Cricket. sudo nano /etc/mosquitto/ mosquitto.conf Add the following lines at the top and save: port 1883 allow_anonymous true Fig.9 should make this clear. Now enable the broker and allow it to autostart on boot up using the following command: sudo systemctl enable mosquitto. service Fig.11. mqtt in node topic configuration. Practical Electronics | October | 2021 This will return the Mosquitto version that is running on your RPi. For more information on how to install M o s q u i t t o M Q T T Fig.12. Configuring mqtt server. broker on an RPi, visit: https://bit.ly/pe-oct21-iot3 In order to configure Cricket we need Soon, we will start building a flow in to attach the batteries and press the builtNode-RED to receive MQTT messages in button for five seconds until the LED using an MQTT node. But before that starts flashing fast. Then connect to the we need to configure a Cricket to send ‘toe_device’ hotspot from any device with data over MQTT to our system. web browser capabilities. Set your Wi-Fi credential and note down the SN (serial) from the INFO panel. The setting should Configuring Cricket to send be as shown in Fig.10. (Note: you need sensor data via MQTT to adjust the IP address in the ‘url’ box The Cricket IoT module transmits the to match your RPi.) temperature and battery voltage level to We set the Cricket to wake up every 30 the /SERIAL/temp and /SERIAL/batt seconds because that is a good interval topics respectively, where SERIAL is for experimenting with data and setting the unique serial number of the Cricket up this project. However, once you are module. Before starting the flow, let’s find done with this project, please change it the serial number of the Cricket module to an interval that makes more sense, for and configure it to transmit temperature example, once an hour or more. Your (using the built-in temperature sensor) and batteries will thank you! battery level through MQTT. (We won’t Now you can exit from the configuration discuss the whole configuration process mode and the device is ready. Cricket is here. For more configuration details refer sending data to our local MQTT broker to Part 1 in the June 2021 issue.) every 30 seconds, so next we will make Cricket comes with a built-in a flow to receive the data from the broker temperature sensor (or, if you want, you and show it in a graphical dashboard. can add any other external analogue sensor to its IO2 pin). We need to configure it to send this temperature value via MQTT. Receiving an MQTT message We’ll configure it to send the temperature in Node-RED every 30 seconds to our system. Since it’s To receive an MQTT message, drag and running on battery power we can place drop an ‘mqtt in’ node into the workspace. and monitor the temperature anywhere Then double click to configure it for Cricket at home or even outside in the garden. and our local MQTT broker. Enter your Fig.13. mqtt server and topic added. 61 Fig.16. Installing node-red-dashboard. Fig.14. MQTT messages received in Node-RED. Go to the install tab, type for node-red-dashboard and click the install button, as shown in Fig.16. Close the window when done. Now we are ready to create a dashboard. We already know our device and the topics it is sending out. Therefore, we can precisely set the topics for the data that interest us. In our case, the device is reporting temperature and battery level in the following topics: /YOUR_CRICKET_SERIAL_NUMBER/temp /YOUR_CRICKET_SERIAL_NUMBER/batt Therefore, your topic should look something like this: /887C3E0039/temp Now let’s create the whole diagram from scratch. In the workspace, add:  Two ‘mqtt in’ nodes and assign the above topics  A chart node (for temperature) from the dashboard palette and connect it with the temp mqtt input  A ‘gauge’ node (for battery) and connect it with the batt mqtt input  A ‘function’ node between the batt mqtt input and the gauge node to calculate the percentage power of the battery Fig.15. Opening Node-RED Manage palette. topic in the topic field (eg, /SERIAL/# for receiving all messages from Cricket; /SERIAL/temp for temperature; and /SERIAL/batt for battery voltage). I set the topic to receive all the messages and thus observe all the MQTT data sent by Cricket (see Fig.11). We also need to tell Node-RED to connect to our local MQTT broker from where the messages are expected to be coming. To do this we need to add mqtt-broker by clicking on the pen icon. A new window will open as shown in Fig.12. In the connection tab enter the server name (eg, the IP address of the RPi). Click Add and then Done. See Fig.13. To watch the received message from the mqtt broker we also need a debug node. Add a debug node and wire it with the mqtt in node. Now deploy the flow and you will receive the MQTT messages from Cricket every 30 seconds, as shown in Fig.14. You need to assign a group for the chart and gauge nodes. Double click on the nodes and assign ‘Home’ group with ‘Reading Room’ Tab for both nodes. Optionally you can set label for the chart and gauge nodes. See Fig.17 for details. Creating a Node-RED dashboard It would be useful to have a nice user interface (UI) instead of just a raw data print out. The good news is Node-RED enables us to build a good UI, which we will use to build a basic dashboard for our device to plot temperature data and show the battery status. First, we need to install one extra component called ‘nodered-dashboard’ for Node-RED. To do that, click on the account icon from top right and select ‘Manage palette’ – see Fig.15. 62 Fig.17. Editing chart node. Practical Electronics | October | 2021 Fig.18. Complete Node-RED flow for receiving sensor data and visualising in graphical dashboard. The complete flow will look like Fig.18. Now we are ready to deploy and open our dashboard by using the same link address as we used to open the Node-RED editor. We only need to add a /ui suffix at the end of the address. In our case the link looks as follow: http://192.168.1.103:1880/ui After going to the address, you will find the elegant dashboard shown in Fig.19. Summary Cricket reports a battery voltage with a number from 0-255. We will convert the value to a percentage using the function node. Double click the function node and paste the following lines into the editor and click done: msg.payload = parseInt((msg. payload / 255) * 100) return msg; We can now enjoy our own live dashboard of our Wi-Fi automation system on any computer or phone. Of course, this was a very basic project – just putting together a temperature sensor and the basics of creating a simple dashboard. Nevertheless, it’s laid the foundations of what we’ll need to build on for much more advanced systems in the future. In this project we have shown the essential hardware and software needed to start building low-power, energyefficient automation systems. Node-RED and Cricket enable Fig.19. Dashboard created by Node-RED. us to build advanced systems without writing any code. This results in a rapid deployment of powerful IoT solutions and automation. In upcoming articles we will add all sorts of environmental and security sensors and support systems – great things to look forward to! ESR Electronic Components Ltd Fig.20. Complete system with Raspberry Pi, live Cricket and the Node-RED dashboard on a smartphone web browser. Cricket special offer! PE / OKdo.com We hope this and June’s Cricket articles have inspired you to experiment with IoT and build your own lowcost, low-power Internet of Things projects. All of our stock is RoHS compliant and CE approved. Visit our well stocked shop for all of your requirements or order on-line. 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