Node-RED tutorial: How to get GPS coordinates with a Maps Widget

Introduction

Node-RED?is a programming tool to wire together hardware devices, APIs and online services in new and interesting ways.

It provides a browser-based editor that makes it easy to wire together flows using the wide range of nodes in the palette that can be deployed to its runtime in a single-click.

As it is quite fascinating to use for open source projects, you are going to learn how to get GPS coordinates from your?SIM7600E?module and put them in a?Google Maps Widget?in Node-RED Dashboard.

Installing and Upgrading Node-RED

In order to start your Node-RED application, you must check if you already have Node-RED installed in your Industrial Panel PC. If you do not have it already installed, run the following command to download and run the script to install Node.js, npm and Node-RED onto?a Raspberry Pi.

sudo apt install build-essential git        

?bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)        

The script above will:

• Remove the pre-packaged version of Node-RED and Node.js if present.
• Install the current Node.js LTS release using the NodeSource. If it detects Node.js is already installed from NodeSource, it will ensure it is at least Node 8, but otherwise it will leave it alone.
• Install the latest version of Node-RED using npm.
• Optionally, install a collection of useful Pi-specific nodes.
• Setup Node-RED to run as a service and provide a set of commands to work with the service.

Autostart on boot

If you want Node-RED to run when the Pi is turned on, or re-booted, you can enable the service to autostart by running the command:

sudo systemctl enable nodered.service        

To disable the service, run the command:

sudo systemctl disable nodered.service        

GPSD

GPSD is a monitor daemon that collects information from GPS, differential-GPS radios, or AIS receivers attached to the host machine. Each GPS, DGPS radio, or AIS receiver is expected to be connected directly to the host via a USB or RS232 serial device. So, to link the data you get from your Serial Port (See how?here >>) to Node-RED, just download some gpsd nodes:?node-red-contrib-gpsd

Go to the Side Tab Menu > Click on Manage Palette > Install > Type "gpsd" > Install the?node-red-contrib-gpsd?package:

Install Map nodes

Now, you are going to install some nodes for the Map Widget.

Go to the Side Tab Menu > Click on Manage Palette > Install > Type "web-worldmap" > Install the?node-red-contrib-web-worldmap?package:

Getting GPS Coordinates

Once installed, type:?gpsd?in the filter nodes search bar, and drag and drop the?Adafruit Ultimate GPS node?to your flow. Add a?switch node?and evaluate the property:?msg.payload.class == (string) TPV?and connect it to a?debug node?like this:

You will see that you will start receiving data immediately, every second. So, if you want to control that time, just add a Delay node between the Adafruit Ultimate GPS node and the switch node, with the configuration you want. For example, try receiving 1 msg every 5 seconds, and drop intermediate messages.

Add the WorldMap node

Once you get all the GPS data, you are going to add two world map nodes so that it displays in the Dashboard correctly:

If you take a look at the node help documentation, the minimum msg.payload from?the worldmap nodes,?must contain?name,?lat?and?lon?properties.

E.g. { "name": "John", "lat": 41.45, "lon": 1.53 }        

So, as you already get the lat and lon properties from the GPS, you need the msg.payload.name. So, let's add a change node, and set msg.payload.name to "Worldmap" (or any name):

Connect this to the world map node as shown below:

And go to your Dashboard to check your map with your location! Your flow should something be like this:

[{"id":"6e545ede.d4925","type":"tab","label":"Flow 1","disabled":false,"info":""},{"id":"7a97b4c5.876cfc","type":"gpsd","z":"6e545ede.d4925","name":"Adafruit Ultimate GPS","hostname":"0.0.0.0","port":"2947","tpv":true,"sky":true,"info":false,"device":true,"gst":false,"att":false,"x":140,"y":200,"wires":[["6560f5f6.c0ed8c"]]},{"id":"6560f5f6.c0ed8c","type":"switch","z":"6e545ede.d4925","name":"","property":"payload.class","propertyType":"msg","rules":[{"t":"eq","v":"TPV","vt":"str"}],"checkall":"true","repair":false,"outputs":1,"x":350,"y":200,"wires":[["4d22a0bd.63dda"]]},{"id":"2cf3ed7c.bd6ad2","type":"ui_worldmap","z":"6e545ede.d4925","group":"88f77589.0122d8","order":2,"width":"14","height":"14","name":"Worldmap ","lat":"","lon":"","zoom":"","layer":"OSM grey","cluster":"","maxage":"","usermenu":"show","layers":"show","panit":"true","panlock":"false","zoomlock":"true","hiderightclick":"false","coords":"deg","showgrid":"false","allowFileDrop":"false","path":"/mapui","x":710,"y":120,"wires":[]},{"id":"4d22a0bd.63dda","type":"change","z":"6e545ede.d4925","name":"","rules":[{"t":"set","p":"payload.name","pt":"msg","to":"Worldmap","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":540,"y":200,"wires":[["23b5e03.345882"]]},{"id":"23b5e03.345882","type":"worldmap","z":"6e545ede.d4925","name":"","lat":"","lon":"","zoom":"","layer":"Esri Satellite","cluster":"","maxage":"","usermenu":"show","layers":"show","panit":"false","panlock":"false","zoomlock":"false","hiderightclick":"false","coords":"none","showgrid":"false","allowFileDrop":"false","path":"/mapui","x":730,"y":200,"wires":[]},{"id":"88f77589.0122d8","type":"ui_group","name":"","tab":"c4c17961.4519f8","order":1,"disp":true,"width":15,"collapse":false},{"id":"c4c17961.4519f8","type":"ui_tab","name":"Location","icon":"dashboard","disabled":false,"hidden":false}]