RPi-iot-demo-2017

MQTT demo client for Raspberry Pi

Javascript app (node.js) that reads temperatures on a Pi and makes available using MQTT.

The client code also:

• Runs webserver for displaying MQTT data charts and diagrams.

• Talks to Pi GPIO hardware, reading switches and controlling LEDs.

Temperature Chart

Dashboard

Requirements

node.js - Recommend node.js installation using NVM. Tested with latest node.js (v7.3.0).

• Refer to PI_PREP.md

MQTT Broker running on network, with WebSockets enabled

• This demo uses mosquitto running on a Pi Model 2. Refer to raspi-demo.conf and Mosquitto on Pi

Raspberry Pi. - Tested with Raspbian jessie on Pi 2 and Pi B+ models

• (OPTIONAL) LEDs, Resistors, capacitor, a switch and wiring. See SCHEMATICS.md for details.

MQTT Topic Structure

MQTT PubSub topic structure being used in this demo

// Topic Structure
// =================
// iot-demo     \
// `-<clientId>  } base topic for this client
//   |          /
//   |-> connected        - 'true' or 'false'
//   `-raspi
//     |-> redled         - 'on' or 'off'
//     |-> greenled       - 'on' or 'off'
//     |-> cputemp        - degrees C
//     `-> gputemp        - degrees C

So Topic "iot-demo/+/connected" is status across all the clients

Implementation

client/index.js

• Publishes information topics using MQTT

• Web server, for displaying MQTT data pages (described below)

• Read and Control GPIO pins on a Raspberry Pi (Switch, LEDs)

client/public/index.html

Displays a scrolling chart of MQTT temperature data streaming from Raspberry Pi using Javascript

• Uses MQTT over WebSockets + a Javascript graphing library

client/public/dashboard.html

Displays real-time status "dashboard" for multiple Pis using Javascript.

• Uses web technologies like WebSockets and SVG. Uses MQTT (over WS) for realtime updates.

For the MQTT Broker used in this demo, see PI_PREP.md. Can run broker on same Pi as client.

Getting Started With A Client Pi

Assuming requirements are met, you can get a copy of the code by cloning git repository from GitHub:

Edit create-config.js script to match your environment. It has values for broker name/WS port.

cd iot-demo
cd client
npm install
./create-config.js
node index.js

If everything is working, can visit URL to view index.html ( e.g., http://client:3000 ) for a "real-time" graph of the Pi temperatures. Your browser must support WebSockets for graphing to work-- most modern ones do.