Fabio Rodrigues

IoT AWS & Azure Smart Meeting Room

Bringing efficiency to space utilization at most end-user location convenience.

IntermediateFull instructions providedOver 1 day261
IoT AWS & Azure Smart Meeting Room

Things used in this project

Hardware components

Adafruit PIR (motion) Sensor
Adafruit Half-size breadboard
Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500

Software apps and online services

Amazon Web Services AWS IoT
AWS API Gateway
Amazon Web Services AWS API Gateway
Amazon Web Services AWS EC2
AWS Lambda
Amazon Web Services AWS Lambda
Amazon Web Services AWS S3
AWS DynamoDB
Amazon Web Services AWS DynamoDB
Amazon Web Services AWS CloudWatch
Microsoft Azure
Microsoft Azure
Azure Active Directory, Microsoft Graph API 1.0 and Office 365 Exchange Online
Arduino IDE
Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)
Solder Wire, Lead Free
Solder Wire, Lead Free


Read more

Custom parts and enclosures

Smart Meeting Room Slide-Pack Presentation

This is a slide-pack bringing step-by-step details about the E2E architecture adopted, IoT sensors, Client-side App, AWS Services / Azure Services configurations, code and screen shots

Mosquitto MQTT Broker Server Setup

Mosquitto is the choice of MQTT Broker, placed between MQTT clients (publisher sensors) and AWS IoT Core (IoT Connectivity Manager). The broker is responsible for receiving all messages, filtering the messages (on #topic basis), determining who is subscribed to each message, and sending the message to these subscribed clients. The broker also holds the sessions of all persisted clients, including subscriptions and missed messages. Another responsibility of the broker is the authorization of clients done on MQTT Broker and initiate TLS authentication procedure towards the AWS IoT Core.

MQTT Broker AMI based on Mosquitto 1.4.5 is available at UE-EAST-1 region (N. Virginia), as found below. Just select Community AMIs at left frame and search by “mqtt” string.

Launch Configuration for ASG can be created using indicated AMI and attached “user-data” in order to automate a couple tasks, such as “MQTT broker thing” creation at IoT Core, configuration of Mosquitto broker, etc. Zip file contains Broker configuration files, http index file (for http server used for Network Load Balancing monitoring) and customized init.d/mosquitto service file (stored in a S3 bucket and downloaded via VPC endpoint to avoid public access). In order to run under AWS free tier, ASG is made of 1 desired/max EC2 VM.


Feather Pinout


PublishPIRSensor-MQTTadafruit - pub.ino

Microcontroller has to be uploaded with the attached Arduino code and be provided with the following data:

const char* googleApiKey = "xxxxxxxxxxxxxxxxxxxx";
char ssid[] = "xxxxxx";
char pass[] = "xxxxxx";

googleApiKey has to be acquired from https://developers.google.com/maps/documentation/geolocation/intro, where billing details has to be provided. In case do you exceed the free tier credit, this will not incur in any charge. Note that the code request Geolocation of the microcontroller once at power-on, so it is unlikely that you exceed the free tier credit, even you decide to use for dozens of rooms.
SSID from closest access point is required, along with password. pass is optional and is required when WPA/WPA2 auth method is used instead of open access.

MQTT Broker details:

#define host “<MQTT Broker IP address or FQDN if DNS is used: i.e.: AWS Route53>“
#define clientid "<prefix>-meetingroom1“
//Common prefix is used to implement some level of access control at MQTT Broker Server
//clientid also must match user-part of room mailbox address, configured via o365 admin
#define username "sensor1“
#define password "sensor123“
//username and password is used for ACL purposes too at MQTT Broker side. More details will be provided MQTT Server side.
 * Publish/Subscribe MQTT PIR Sensors for Smart Meeting Rooms IoT Use Cases 
 * Copyright (C) 2019 Fabio R. Caetano fabior_bra@yahoo.com.br
 * This file is distributed in the hope that it will be useful, but without any warranty; without even
 * the implied warranty of merchantability or fitness for a particular purpose.

#include <WiFi101.h>
#include <WifiLocation.h>
#include <SPI.h>
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"

const char* googleApiKey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
char ssid[] = "xxxxxx";
char pass[] = "xxxxxx";

#define host      "<MQTT Broker IP address or FQDN>"
//if DNS is used: i.e.: AWS Route53>"
#define clientid  "<prefix>-meetingroom1"
//clientid must match user-part of room mailbox address, configured via o365 admin
#define username  "sensor1"
#define password  "sensor123"
String mqttpayload1;
String mqttpayload2;
String mqttpayload3;

WiFiClient wificlient;
Adafruit_MQTT_Client mqttclient(&wificlient, host, 1883, clientid, username, password);
WifiLocation location(googleApiKey);

int ledPin = 13; // choose the pin for the LED
int inputPin = 5; // choose the input pin (for PIR sensor)
int pirState = LOW; // we start, assuming no motion detected
int val = 0; // variable for reading the pin status
int status = WL_IDLE_STATUS;

// You don't need to change anything below this line!
#define halt(s) { Serial.println(F( s )); while(1);  }

/****************************** Feeds ***************************************/

// Setup a feed called 'sensor/#' for publishing.
// Notice MQTT paths for AIO follow the form: <username>/feeds/<feedname>
Adafruit_MQTT_Publish topiclocation = Adafruit_MQTT_Publish(&mqttclient, "pir_sensor/location/" clientid);
Adafruit_MQTT_Publish topicstate = Adafruit_MQTT_Publish(&mqttclient, "pir_sensor/state/" clientid);

// Setup a feed called 'onoff' for subscribing to changes.Future use only. intended to trigger monitoring only when room is booked.
Adafruit_MQTT_Subscribe onoffmonitor = Adafruit_MQTT_Subscribe(&mqttclient, "pir_sensor/onoffmonitor");

/*************************** Sketch Code ************************************/

void setup() {
// while (!Serial);

  Serial.println(F("Adafruit MQTT demo for WINC1500"));

  // Initialise the Client
  Serial.print(F("\nInit the WiFi module..."));
  // check for the presence of the breakout
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WINC1500 not present");
    // don't continue:
    while (true);
  Serial.println("ATWINC OK!");
  pinMode(ledPin, OUTPUT); // declare LED as output
  pinMode(inputPin, INPUT); // declare sensor as input


  MQTT_connect(); // Call once on setup to send Room Sensor Location
  location_t loc = location.getGeoFromWiFi();

  Serial.println("Location request data");
  Serial.println("Latitude: " + String(loc.lat, 7));
  Serial.println("Longitude: " + String(loc.lon, 7));
  Serial.println("Accuracy: " + String(loc.accuracy));

  mqttpayload1 = "{\"Location\": \"";
  mqttpayload2 = "\"}";
  mqttpayload3 = mqttpayload1 + String(loc.lat, 7) + String(",") + String(loc.lon, 7) + String(",") + String(loc.accuracy) + mqttpayload2;
  const char *publishloc = mqttpayload3.c_str();


void loop() {
  // Ensure the connection to the MQTT server is alive (this will make the first
  // connection and automatically reconnect when disconnected).  See the MQTT_connect
  // function definition further below.

  // this is our 'wait for incoming subscription packets' busy subloop
  Adafruit_MQTT_Subscribe *subscription;
  while ((subscription = mqttclient.readSubscription(5000))) {
    if (subscription == &onoffmonitor) {
      Serial.print(F("Got: "));
      Serial.println((char *)onoffmonitor.lastread);

      if (0 == strcmp((char *)onoffmonitor.lastread, "OFF")) {
        digitalWrite(ledPin, LOW);
      if (0 == strcmp((char *)onoffmonitor.lastread, "ON")) {
        digitalWrite(ledPin, HIGH);

 val = digitalRead(inputPin); // read input value
  if (val == HIGH) { // check if the input is HIGH
      digitalWrite(ledPin, HIGH); // turn LED ON
      if (pirState == LOW) {
        // we have just turned on
        mqttpayload1 = "{\"State\": \"Detected\"}";
        const char *publishstate = mqttpayload1.c_str();
        // We only want to print on the output change, not state
        pirState = HIGH;
  } else {  
      digitalWrite(ledPin, LOW); // turn LED OFF
      if (pirState == HIGH){
        // we have just turned of
        mqttpayload1 = "{\"State\": \"End\"}";
        const char *publishstate = mqttpayload1.c_str();
//        topicstate.publish(publishstate);
        // We only want to print on the output change, not state
        pirState = LOW;


// Function to connect and reconnect as necessary to the MQTT server.
// Should be called in the loop function and it will take care if connecting.
void MQTT_connect() {
  int8_t ret;

  // attempt to connect to Wifi network:
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print("Attempting to connect to SSID: ");
    // Connect to WPA/WPA2 network. Change this line if using open or WEP network:
    status = WiFi.begin(ssid, pass);

    // wait 10 seconds for connection:
    uint8_t timeout = 10;
    while (timeout && (WiFi.status() != WL_CONNECTED)) {
  // Stop if already connected.
  if (mqttclient.connected()) {

  Serial.print("Connecting to MQTT... ");

  while ((ret = mqttclient.connect()) != 0) { // connect will return 0 for connected
       Serial.println("Retrying MQTT connection in 5 seconds...");
       delay(5000);  // wait 5 seconds
  Serial.println("MQTT Connected!");

Check_room_occupancy Lambda Function

This function read the provisioned meeting rooms from table "pir_sensor_location" and verify its current occupancy state, by reading last entry from table "pir_sensor_state" for each provisioned meeting room. If it is declared occupied, no further action is taken and its corresponding state it kept updated in the table "pir_sensor_location". On the other hand, if declared available based on configured "occupancy_timer" passed to the function via Cloudwatch event, Microsoft Graph API to get access token based on client secret is called (using ADAL), whereas is stored for 1 hour to avoid new API access token request calls within this period. With the token, each available meeting room is queried via MS Graph API GET Events, filtered by start time (minus occupancy_timer) to declare that meeting room booking is subject of cancellation, once occupancy_timer has timed out since its initial reservation timer, then MS Graph API DELETE event is called to cancel the booking and allowing future booking of the remaining time.

Deployment package (Python 3.7) found attached. Please note that it is greater than 3MB and and it is not possible to edit the code at lambda GUI directly. Environment variables are found at enclosed slide-pack and Azure AD related variables values ( where to locate?), are found at slide 15.

How to upload the deployment package: i.e.: aws lambda update-function-code --function-name Check_room_occupancy --zip-file fileb://Check_room_occupancy.zip
No preview (download only).

List_rooms_onlocation Lambda Function

This function is called by AWS API Gateway at each Client Desktop App call, in order to provide the list of closest available rooms based on end-users wifi location, where top 4 only are provided back to the end-user.
Deployment package written in Python 3.7 and environment variables used are found at the enclosed slide-pack.

API Gateway configuration found in the slide-pack enclosed.
No preview (download only).

Mosquitto MQTT Broker Server EC2 - User Data scripts

EC2 Mosquitto Broker once instantiated, will trigger broker thing creation, IAM policy for the bridge creation, certificates and keys creation and download, attach the policy to the certificate and finally attach the policy to your thing automatically, via EC2 user-data bash script attached,
yum -y update

#Configure the CLI with your region, leave access/private keys blank
aws configure set default.region us-east-1

#Create a Broker Thing
aws iot create-thing --thing-name "mosquittobroker"

#Create an IAM policy for the bridge
aws iot create-policy --policy-name bridge --policy-document '{"Version": "2012-10-17","Statement": [{"Effect": "Allow","Action": "iot:*","Resource": "*"}]}'

#Place yourself in Mosquitto directory
#And create certificates and keys, note the certificate ARN
mkdir -p /etc/mosquitto/certs/
cd /etc/mosquitto/certs/
aws iot create-keys-and-certificate --set-as-active --certificate-pem-outfile cert.crt --private-key-outfile private.key --public-key-outfile public.key --region us-east-1

#List the certificate and copy the ARN in the form of
# arn:aws:iot:us-east-1:[AWS Account ID]:cert/xyzxyz
aws iot list-certificates --max-items 1 > iot-last-certificate.txt

#Attach the policy to your certificate
aws iot attach-principal-policy --policy-name bridge --principal arn:aws:iot:us-east-1:[AWS Account ID]:cert/`cat iot-last-certificate.txt |grep certificateArn|tr -d '",'|awk -F 'certificateArn:' '{print substr($2,42)}'`

#Attach the policy to your thing
aws iot attach-thing-principal --thing-name "mosquittobroker" --principal arn:aws:iot:us-east-1:[AWS Account ID]:cert/`cat iot-last-certificate.txt |grep certificateArn|tr -d '",'|awk -F 'certificateArn:' '{print substr($2,42)}'`

#Add read permissions to private key and client cert
chmod 644 private.key
chmod 644 cert.crt

#Download root CA certificate
wget https://www.symantec.com/content/en/us/enterprise/verisign/roots/VeriSign-Class%203-Public-Primary-Certification-Authority-G5.pem -O rootCA.pem

#download the configuration file from S3
cd /etc/mosquitto
aws s3 cp --recursive s3://[mqtt-broker-S3bucket]/conf/ .
chmod 666 logfile.log
chmod -R 777 persistent/

#download http index file from S3
cd /var/www/html
aws s3 cp --recursive s3://[mqtt-broker-S3bucket]/www/ .
chmod 666 index.html

#Starts Mosquitto in the background
mosquitto -d -c /etc/mosquitto/bridge.conf

#Enable Mosquitto to run at startup automatically
cd /etc/init.d
aws s3 cp s3://[mqtt-broker-S3bucket]/init.d/mosquitto .
chmod 755 mosquitto
chkconfig --level 345 mosquitto on
chkconfig --level 345 httpd on

Client Desktop App

Client desktop App is coded in python 3.7 for simplicity and prototyping purposes.

Run it using c:\python .\getFreeRoomsLocation.py

Or use pyinstaller for executable creation and easy distribution. Suggest to pack it one directly instead of one file due performance purposes:

What to configure/customize?

# Google Geoloction api-endpoint + Key
URL = "https://www.googleapis.com/geolocation/v1/geolocate?key=xxxxxxxxxxxxxxxxxxxxxxxxxx"

# api-gateway endpoint, found at AWS API Gateway GUI, left frame menu "Dashboard" of concerned API
URL_APIG = "https://xxxxxxxxxxxxxxxxxxxxxxxxxx"
import subprocess
import operator
import requests 
import json
import os
import sys

class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            if o % 1 > 0:
                return float(o)
                return int(o)
        return super(DecimalEncoder, self).default(o)
def bssidlist (ssids):
# This function order the list of MAC addresses by RSSI (signal strenght) and return the top 3

	sorted_keys = sorted(ssids, key=lambda x: (ssids[x]['Signal']), reverse=True)
#	print(sorted_keys)

	aplist = list()
	for x in sorted_keys:
#		print(ssids[x]['BSSID'])
	return aplist[:3]

def fetchUlocation (macaddr):
# This function calls Google Geolocation API based on Wi-Fi Access Points MAC addresses and respective RSSI
	# api-endpoint 
	URL = "https://www.googleapis.com/geolocation/v1/geolocate?key=xxxxxxxxxxxxxxxxxxxxxxxxxx"
	# data to be sent to api
	macdata0 = "{'considerIp': 'false', 'wifiAccessPoints': ["
	macdata1 = "{'macAddress': '"
	macdata2 = "'}, {'macAddress': '".join(macaddr)
	macdata3 = "'}]}"
	macdata = json.dumps(macdata0+macdata1+macdata2+macdata3)
	macdata = macdata.strip('"')
#	print(macdata)
	headers = {"content-type": "application/json charset=utf-8"}
	# sending post request and saving response as response object 
	r = requests.post(URL, data = macdata, headers = headers) 
	# extracting response text  
	pastebin_url = r.json()
#	print("The pastebin URL is:%s"%pastebin_url)
	return pastebin_url
def fetchrooms (user_geoloc):
#This function calls AWS API Gateway endpoint which in turns calls lambda function List_rooms_onlocation, it provides rooms location and #get in return the closest available rooms	

	# api-gateway endpoint 
	URL_APIG = "https://xxxxxxxxxxxxxxxxxxxxxxxxxx"
	# data to be sent to api
	#user_geoloc = user_geoloc.strip('"')
#	print(user_geoloc['location'])

	params = {'Latitude': user_geoloc['location']['lat'], 'Longitude': user_geoloc['location']['lng']}
	headers_get = {"content-type": "application/json"}
	# sending get request and saving response as response object 
	req = requests.get(URL_APIG, params=params, headers = headers_get) 
	# extracting response text  
	resp = req.json()
	return resp

def main():		
	results = subprocess.check_output(["wifi", "scan"])
	results = results.decode('utf-8') # needed in python 3
	results = results.replace("\r","")
	ls = results.split("\n")
	ls = ls[4:]
	ssids = {}
	ssids_hlist = {}
	x = 0
	y = 0
	r = 0
	while x < len(ls):
		if "BSSID" in ls[x]:
			ssids_add = {
						'BSSID'	:	ls[x].replace(" ","")[7:],
						'Signal':	ls[x+1].replace(" ","")[7:]
			ssids[y] = ssids_add
			y += 1
		x += 1
	geoloc = fetchUlocation(bssidlist(ssids))
	list_rooms = fetchrooms(geoloc)

	os.system('cls')  # on windows
	for r in list_rooms:
		print(r['Room'],"is available at",int(r['Distance']),"meters")
	input('Press any key to exit')



Fabio Rodrigues

Fabio Rodrigues

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