Published February 1, 2018 © GPL3+

Visitor Counter

Count visitors in a place and publish on Losant dashboard.

IntermediateShowcase (no instructions)4 hours2,100

Things used in this project

Hardware components

Particle Photon

Breadboard (generic)

LED (generic)

Adafruit IR Break Beam Sensor

Software apps and online services

Losant Platform

Story

This is a Project in connection with the course "IoT Ecosystems" which took place at the Esslingen University of Applied Sciences in the Winter Semester 2017/18.

The idea

If you ask google for a particular place like a fitness studio, a restaurant or a store, it most likely will give you a small diagram, telling you about frequencies of people visiting the store. The diagram is based on tracking data from their smartphones.

We wanted to build a prototype, which gives us a more precise information on how many people are actually visiting a fitness studio, a store, a hairdresser, or any other particular room, hall or building.

To provide this information to everyone interested , we will publish this information online.

The board

The particle photon was our choice due to the nice web IDE and the ability to flash the device OTA. We attached two IR Units for both, sending ad receiving IR signals to detect motion.

IR sender/receiver

The sensors are connected to the analog inputs of the photon. Each sensor has its own ISR (interrupt service routine) to handle the events which are fired when the voltage of the analog input changes (movement is detected).

So, why do we have two sensors? Because we want to know if someone is entering, or leaving our room. We recognize this by the order in which the sensors detect movement.

Beside the sensors, there is a LED indicating the state of the counter. This is helpful for debug and testing.

Programming the Photon

To increase or decrease the counter, we need to track the state of our two sensors. The question is, if a ISR is activated, is a person actually entering, or leaving the room? To figure this out, we need some kind of a state machine, which always reflects a particular state. In our case, we have three simple states:

Nothing happens

Someone coming (s0)

Someone going (s1)

Our state machine, allowing us to recognize people entering (so) or leaving (s1) the party

Now, we can count persons coming, or leaving by simply in- or decreasing a variable.

As of now, we do not know about how many people in total are in that room. We decided to keep this information 'in the cloud', not on the photon board. Why? First, that makes it easier to handle a room with more than one door. And if a photon has to restart, we wont loose the total number of persons in that room.

Communication with Losant

Next step is to publish our Counter to Losant. We will do this using MQTT, since Losant has a build in MQTT Broker which allow us to publish messages.

As a security measure, we need to allow a MQTT client to push to a particular Losant application. This means:

You have to create a Losant application (read this)

Create a device (read this)

Create a access key (read this)

Insert the access key, secret and your device id into the code.

#define DEVICE "<device id from losant>"       // ID Of my Device
#define ACCESS "<access key from losant>"
#define SECRET "<access secret from losant>"
#define TOPIC "losant/<device id from losant>/state"

Business logic at losant

Now it is time for the counter, we will

Save a total for a room

Add logic to increase or decrease that total

Add a second device, to update the dash board.

Therefore we need to

create a data table, (read this)

and a workflow (read this)

The data table should have two column (beside the default columns):

total with datatype number

device with data type string

The workflow should look like this:

The workflow gets the offset from the photon, gets the total from our data table, calculates the new total, and writes it back to the table. Then our 'total' device is triggered, to update the dashboard.

You can import this workflow, the file is attached. You can read on how to import a workflow here.

Displaying data

The dashboard shows the current number of people in the room. If someone enters or leaves the room, the dashboard will indicate this by increasing or decreasing the number displayed. Lean on how to use the dashboard here

Dashboard at Losant, showing the total of visitors in our room.

Code

/*
 *  This file is a sample application, based
 *  on the IoT Prototyping Framework (IoTPF)

    This application and IoTPF is free software: you can redistribute it     and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    IoTPF 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.  See the
    GNU v3 General Public License for more details.

    Released under GNU v3

    You should have received a copy of the GNU General Public License
    along with IoTPF.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
    Internet of Things Prototyping Framework IoTPF  
    @Version 1.0
    @author Dionysios Satikidid
    
    Visitor Counter (out of SmartAtmo) 2017/2018
    @version 1.0
    @author Rasid Music, Thomas Günter
*/

#include <ArduinoJson.h>                        // JSON Library for serialisation of the payload
#include "StatusLed.h"                          // Helper class, uses a led to indicate codes via a led
#include "MqttLauncher.h"                       // Wrapper for MQTT client, providing some convenience for sending sensor data

#define TTL 60                                  // Time to live for messages published to particle cloud
#define LOOP_DELAY 1000                         // Delay for repeating the loop function in ms
#define PUBLISHING_DELAY 10000                  // Delay for publishing data to cloud
#define LOSANT_BROKER "broker.losant.com"       // URL of the Losant MQTT Broker
#define DEVICE "<<losant device id>>.   "       // ID Of my Device
#define ACCESS "<<losant access key>>"          // Access Secret
#define SECRET "<<losant access secret>>"       // Access Secret
#define TOPIC "losant/<<losant device id>>/state" // Topic for Measurements

enum MotionState {no_motion, s0, s1, illegal};  // Enumeration describing the states of the motion sensor
void callback(char* topic, byte* payload        // callback method for the mqtt client
    , unsigned int length);
void isr0(void);                                // Interrupt Service Routine for motion sensor
void isr1(void);                                // Interrupt Service Routine for motion sensor

int loopCounter = 0;                            // counter for publishing mqtt message
volatile MotionState state = no_motion;         // state of the motion sensor
volatile int pers = 0;                          // persons in room
volatile long debounce0 = 0;                    // helper for debouncing motion
volatile long debounce1 = 0;                    // helper for debouncing motion
long debounce = 100;                            // value for debouncing of the motion sensor
StatusLed errorLed;                             // Status LED, used to indicate sate
MqttLauncher *mqtt;                             // mqtt wrapper to send data to losant via mqtt
float coo = 0;                                  // value for mq135 readings
MQ135 mq135(MQ135_PORT);                        // Provides access to co2 readings of mq135

   /***** Led Notification ****
    1 - state s0
    2 - state s1
    3 - illegal state
    4 - Failed sending Device Status to Losant
    *****************************/

void setup() {

    /********** Initialize Status LED ******/
    pinMode(D0, OUTPUT);
    errorLed.setLed(D0);


    /********** Initialize ISR ************/
    attachInterrupt(A0, isr0, RISING);
    attachInterrupt(A1, isr1, RISING);


    /********** Initialize MQTT Client ****/
    mqtt = new MqttLauncher(
        LOSANT_BROKER
        , 1883
        , DEVICE
        , ACCESS
        , SECRET
        , callback);


    Particle.publish("getStable/setup", "Setup done");
}

void loop() {

    if(loopCounter >= PUBLISHING_DELAY){
        loopCounter = 0;

        // adding payload
        mqtt->addPayload("pers", pers);
        //mqtt->addPayload("device", 666);

        if(!mqtt->launch(TOPIC)){
            errorLed.notify(4, 200);
        }

        pers = 0;
    }

    errorLed.notify(state, 100);

    delay(LOOP_DELAY);
    loopCounter += LOOP_DELAY;
}

void isr0(){
    if(debounce0 > millis()){
        return;
    }

    switch(state) {
        case no_motion:
            state = s0;
            return;

        case s0:
            return;

        case s1:
            pers--;
            debounce0 = millis() + debounce;
            state = no_motion;
            return;

        default:
            state = illegal;
            return;
    }
}

void isr1(){
    if(debounce1 > millis()){
        return;
    }

    switch(state) {
        case no_motion:
            state = s1;
            return;

        case s1:
            return;

        case s0:
            pers++;
            debounce1 = millis() + debounce;
            state = no_motion;
            return;

        default:
            state = illegal;
            return;
    }
}

void callback(char* topic, byte* payload, unsigned int length) { }

/*
 *  This file is a sample application, based
 *  on the IoT Prototyping Framework (IoTPF)

    This application and IoTPF is free software: you can redistribute it     and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    IoTPF 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.  See the
    GNU v3 General Public License for more details.

    Released under GNU v3

    You should have received a copy of the GNU General Public License
    along with IoTPF.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
    Internet of Things Prototyping Framework IoTPF  
    @Version 1.0
    @author Dionysios Satikidid
    
    Visitor Counter (out of SmartAtmo) 2017/2018
    @version 1.0
    @author Rasid Music, Thomas Günter
*/

#include "application.h"

class StatusLed {

    private:
    int led = 0;
    bool ledState = false;


    public:
    // led will blink n = code times, and toggle with the given frequency in ms
    void notify(int code, int frequency);

    // notify will use the port given in led
    void setLed(int port);

    private:
    // toggles the led and returns the given state (true, or false)
    void toggle();
};



#include "StatusLed.h"

void StatusLed::setLed(int port){
    led = port;
}

void StatusLed::notify(int code, int frequency){
    for(int i = 0; i < code * 2; i++){
        toggle();
        delay(frequency);
    }

    delay(frequency * 2);

}

void StatusLed::toggle(){
    digitalWrite(led, !ledState);
    ledState = !ledState;
}

/*
 *  This file is a sample application, based
 *  on the IoT Prototyping Framework (IoTPF)

    This application and IoTPF is free software: you can redistribute it     and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    IoTPF 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.  See the
    GNU v3 General Public License for more details.

    Released under GNU v3

    You should have received a copy of the GNU General Public License
    along with IoTPF.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
    Internet of Things Prototyping Framework IoTPF  
    @Version 1.0
    @author Dionysios Satikidid
    
    Visitor Counter (out of SmartAtmo) 2017/2018
    @version 1.0
    @author Rasid Music, Thomas Günter
*/

#include <string>
#include <MQTT.h>               // MQTT Client to carry the payloat to losant
#include <ArduinoJson.h>        // JSON Library for serialisation of the payload

#define JSON_BUFFER_SIZE 255    // Size of the Json buffer. This affects the total length of the payload of MQTT messages

class MqttLauncher {

    private:
        String client;
        String device;
        String key;
        String secret;
        int port;
        String url;
        MQTT* mqttClient;
        StaticJsonBuffer<JSON_BUFFER_SIZE> payload;
        JsonObject& root = payload.createObject();
        JsonObject& data = root.createNestedObject("data");

    public:
        // Constructor
        MqttLauncher(String url, int port, String device, String key, String secret ,void (*_callback)(char*,uint8_t*,unsigned int));

        // adds a key val pair to the data section
        void addPayload(String key, int val);
        void addPayload(String key, float val);
        void addPayload(String key, String val);


        // sends the mqtt message, the data section will be deleted
        bool launch(String topic);
};


#include "MqttLauncher.h"

MqttLauncher::MqttLauncher(
        String _url
        , int _port
        , String _device
        , String _key
        , String _secret
        ,  void (*_callback)(char* topic, byte* payload, unsigned int length)) {
    device = _device;
    key = _key;
    secret = _secret;
    url = _url;
    port = _port;

    // stack overflow magic https://stackoverflow.com/questions/7352099/stdstring-to-char
    // without this, call of the MQTT constructor is ambigous
    char *broker = &url[0u];
    mqttClient = new MQTT(broker, _port, _callback);
}

bool MqttLauncher::launch(String topic){
    char buffer[JSON_BUFFER_SIZE];
    root.printTo(buffer, JSON_BUFFER_SIZE);

    mqttClient->connect(device, key, secret);

    if(mqttClient->isConnected()){
        mqttClient->publish(topic, buffer);
        mqttClient->disconnect();

        payload.clear();
        JsonObject& root = payload.createObject();
        JsonObject& data = root.createNestedObject("data");

        return true;
    }else{
        return false;
    }
}

void MqttLauncher::addPayload(String key, int val){
    char *_key = &key[0u];
    data[_key] = val;
}

void MqttLauncher::addPayload(String key, float val){
    char *_key = &key[0u];
    data[_key] = val;
}

void MqttLauncher::addPayload(String key, String val){
    char *_key = &key[0u];
    char *_val = &val[0u];
    data[_key] = _val;
}

{"globals":[],"triggers":[{"config":{},"outputIds":[["bnmWn8SW0y"]],"key":"5a58aa9d6061390006c792b7","type":"deviceId","meta":{"category":"trigger","name":"deviceIdsTags","label":"Device: State","x":300,"y":80,"uiId":"Ko0~1m5ZUR","description":""}}],"nodes":[{"type":"DataTableUpdateRowNode","meta":{"category":"data","name":"update-table-row","label":"Table: Update Row","x":300,"y":540,"description":""},"config":{"dataTableIdTemplate":"5a57c6de261e0b0007edfc3b","rowIdTemplate":"{{data.tablerow.items.0.id}}","dataMethod":"individualFields","resultPath":"","rowFields":[{"columnTemplate":"total","valueTemplate":"{{data.value.new_total}}"}]},"id":"MYnPZFKh9U","outputIds":[["eF5CJbvxU5"]]},{"type":"DataTableQueryNode","meta":{"category":"data","name":"get-table-rows","label":"Table: Get Rows","x":300,"y":220,"queryMode":"$or","description":""},"config":{"dataTableIdTemplate":"5a57c6de261e0b0007edfc3b","sortColumnTemplate":"","sortDirectionTemplate":"","limitTemplate":"","offsetTemplate":"","resultPath":"data.tablerow","queryTemplate":"{\"$or\":[{\"device\":{\"$eq\":\"{{deviceName}}\"}}]}"},"outputIds":[["8XDiCveUXB"]],"id":"bnmWn8SW0y"},{"type":"MathNode","meta":{"category":"logic","name":"math","label":"Math","x":300,"y":380,"description":""},"config":{"statements":[{"expression":"{{data.tablerow.items.0.total}} + {{data.pers}}","resultPath":"data.value.new_total"}]},"id":"8XDiCveUXB","outputIds":[["MYnPZFKh9U"]]},{"type":"DeviceChangeStateNode","meta":{"category":"output","name":"device-state","label":"Device State","x":300,"y":740,"description":""},"config":{"deviceIdTemplateType":"stringTemplate","timeSourceType":"payloadTime","attrDataMethod":"individualFields","deviceId":"5a58add46061390006c792b8","attrInfos":[{"key":"total","valueTemplate":"{{data.value.new_total}}"}]},"id":"eF5CJbvxU5","outputIds":[]}],"name":"VisitorCounter","enabled":true,"description":"","applicationId":"59fc4cc658a69b000749f317","_type":"flow","_exportDate":"2018-01-22T13:29:41.861Z"}

Credits

C Team

2 projects • 0 followers

Visitor Counter

Things used in this project

Hardware components

Software apps and online services

Story

The idea

The board

Programming the Photon

Communication with Losant

Business logic at losant

Displaying data

Schematics

Layout

Code

Code for the .INO file

Status led

MqttLauncher

Workflow to import

Credits

C Team

Comments

Embed the widget on your own site

Visitor Counter

Visitor Counter

Things used in this project

Hardware components

Software apps and online services

Story

The idea

The board

Programming the Photon

Communication with Losant

Business logic at losant

Displaying data

Schematics

Layout

Code

Code for the .INO file

Status led

MqttLauncher

Workflow to import

Credits

C Team

Comments

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