In this tutorial I am going to explain about the measuring the proximity of a device and publishing the values into the Thingsai,io cloud platform by using hall sensor and esp32 development board.

A Hall effect sensor is a device that is used to measure the magnitude of a magnetic field. Its output voltage is directly proportional to the magnetic field strength through it. Hall effect sensors are used for proximity sensing, positioning, speed detection, and current sensing applications.

Step 1: COMPONENTS

Hardware Components:

1. Hall Sensor

2. esp32 development board

3. Jumper wires

Software Components:

1. Arduino IDE

2. ThingsIO.AI

Step 2: CONNECTIONS:

Hall sensor----------------------esp32

Aout------------------------------vp

Gnd-----------------------------Gnd

Vcc------------------------------3V3

Step 3: CODING:

#include <WiFi.h><br>

#include <WiFiMulti.h>

#include <WiFiClientSecure.h>

int count=0,i,m,j,k;

int measurement;

int outputpin= A0;//ds18b20

//////////////////////////////////////// ALL DECLARATIONS
for CLOUD //////////////////////////////

const char* host = "api.thingsai.io";                                 // OR host =
devapi2.thethingscloud.com

const char* post_url = "/devices/deviceData";       // OR
/api/v2/thingscloud2/_table/data_ac

const char* time_server =
"baas.thethingscloud.com";            
//this is to convert timestamp

const int httpPort = 80;

const int httpsPort = 443;

const char*  server =
"api.thingsai.io";  // Server
URL

char timestamp[10];

WiFiMulti WiFiMulti;

// Use WiFiClient class to create TCP connections

   WiFiClient client;

/////////////////////////////////////// TIMESTAMP
CALCULATION function///////////////////////////////////////

int GiveMeTimestamp()

  unsigned long
timeout = millis();

 // WiFiClient client;

  while
(client.available() == 0)

    if (millis() -
timeout > 50000)

      client.stop();

      return 0;

while (client.available())

        String line =
client.readStringUntil('\r');                   
//indexOf() is a funtion to search for smthng , it returns -1 if not
found

        int pos =
line.indexOf("\"timestamp\"");                       //search for
"\"timestamp\"" from beginning of response got and copy all
data after that , it'll be your timestamp

        if (pos >=
0)

          int j = 0;

         
for(j=0;j<10;j++)

           
timestamp[j] = line[pos + 12 + j];

////////////////////////////////////////////////////////////////////////////////////////////////////////

void setup()

   
Serial.begin(115200);

    delay(10);

    // We start by
connecting to a WiFi network

    WiFiMulti.addAP("wifi_name",
"wifi_password");

    Serial.println();

    Serial.println();

   
Serial.print("Wait for WiFi... ");

   
while(WiFiMulti.run() != WL_CONNECTED) {

       
Serial.print(".");

        delay(500);

   
Serial.println("");

   
Serial.println("WiFi connected");

   
Serial.println("IP address: ");

    Serial.println(WiFi.localIP());

    delay(500);

void loop()

  int analogValue =
analogRead(outputpin);

/////////////////////////////////////// SEND THE QUERY AND
RECEIVE THE RESPONSE///////////////////////

      int measurement
= 0;

    measurement =
hallRead();

   
Serial.print("Hall sensor measurement: ");

   
Serial.println(measurement);

    delay(1000);

 
Serial.print("connecting to ");

 
Serial.println(host);                          //defined upside :- host
= devapi2.thethingscloud.com or 139.59.26.117

///////////////////////////////////// TIMESTAMP CODE SNIPPET
/////////////////////////

Serial.println("inside get timestamp\n");

  if
(!client.connect(time_server, httpPort))

    return;                                                       
//*-*-*-*-*-*-*-*-*-*

 
client.println("GET /api/timestamp HTTP/1.1");                            //Whats this part
doing, i didnt get

 
client.println("Host: baas.thethingscloud.com");

 
client.println("Cache-Control: no-cache");

 
client.println("Postman-Token:
ea3c18c6-09ba-d049-ccf3-369a22a284b8");

  client.println();

GiveMeTimestamp();                        //it'll call the function
which will get the timestamp response from the server

Serial.println("timestamp receieved");

Serial.println(timestamp);

 
Serial.println("inside ThingsCloudPost");

  String PostValue =
"{\"device_id\": 
61121696007 , \"slave_id\": 2";

        PostValue =
PostValue + ",\"dts\":" +timestamp;

   PostValue =
PostValue +",\"data\":{\"proximity\":" +
measurement +"}"+"}";

 
Serial.println(PostValue);

/* create an instance of WiFiClientSecure */

WiFiClientSecure client;

   
Serial.println("Connect to server via port 443");

    if
(!client.connect(server, 443)){

       
Serial.println("Connection failed!");

    } else {

       
Serial.println("Connected to server!");

        /* create HTTP
request */

        client.println("POST
/devices/deviceData HTTP/1.1");

       
client.println("Host: api.thingsai.io");

       
//client.println("Connection: close");

       
client.println("Content-Type: application/json");

       
client.println("cache-control: no-cache");

        client.println("Authorization:
Bearer
eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.IjVhMzBkZDFkN2QwYjNhNGQzODkwYzQ4OSI.kaY6OMj5cYlWNqC2PNTkXs9PKy6_m9tdW5AG7ajfVlY");

       
client.print("Content-Length: ");

       
client.println(PostValue.length());

        client.println();

       
client.println(PostValue);

//////////////////////////////////POSTING the data on to the
cloud is done and now get the response form cloud server//////////////////

 Serial.print("Waiting for response
");

        while
(!client.available()){

            delay(50);
//

           
Serial.print(".");

        /* if data is
available then receive and print to Terminal */

        while
(client.available()) {

            char c =
client.read();

           
Serial.write(c);

/* if the server disconnected, stop the client */

        if
(!client.connected()) {

           
Serial.println();

           
Serial.println("Server disconnected");

           
client.stop();

Serial.println("//////////////////////    THE END    
/////////////////////");

delay(3000);

}

Step 4: RESULT:

The values which are read from the sensor are being sent to the IOT cloud successfully and the graph is being created as proximity vs time. With this the working of the sensor is analysed and used according to the required areas of application.