The Engineering Projects

IoT Based Motion Detection with Email Alert using ESP32

The IoT is the interconnection of physical objects or devices with sensors and software accessing capabilities to communicate data or information over the internet.

To build an IoT network, we need an interface medium that can fetch, control, and communicate data between sender and receiver electronics devices or servers.

Espressif Systems created the ESP32 Wi-Fi chip series. The ESP32 module is equipped with a 32-bit Tensilica microcontroller, 2.4GHz Wi-Fi connectivity, an antenna, memory, and power management modules, and much more. All of these built-in features of this ESP32 module make it ideal for IoT applications.

Hello readers, I hope you all are doing great. In this tutorial, we will learn another application of ESP32 in the field of IoT (Internet of Things). We are using a PIR sensor to detect motion and an Email alert will be generated automatically whenever a motion is being detected.

Fig.1

Where To Buy?
No.	Components	Distributor	Link To Buy
1	ESP32	Amazon	Buy Now

Overview

The HCSR-501 sensor module is used with ESP32 to detect the motion. So whenever a motion is detected, the PIR sensor will generate a HIGH output signal which will act as an input to the ESP32 module. In the absence of motion, the output of the PIR sensor will remain LOW. If a HIGH input signal is generated from the PIR sensor module, the LED (either peripheral or inbuilt) will be turned ON and along with that, an Email will be generated to the receiver’s email address as per the program instructions.

Software and Hardware requirements

• ESP32 development board
• HCSR-501 PIR sensor module
• LED
• Resistor
• Connecting Wires
• Sender’s email account details
• Receiver’s email address
• ESP-Mail-Client Library

What is HCSR-502 PIR sensor module and how does it work?

Fig. 2 PIR Motion Sensor

PIR stands for Passive Infrared sensors. It detects heat energy in the surrounding environment using a pair of pyroelectric sensors. Both sensors are placed next to each other, and when motion is detected or the signal differential between the two sensors changes, the PIR motion sensor returns a LOW result (logic zero volts). It means that in the code, you must wait for the pin to go low. The desired function can be called when the pin goes low.

There are two potentiometers available in the HCSR-501 PIR motion sensor module. One of the potentiometers is to control the sensitivity to the IR radiations. Lower sensitivity indicates the presence of a moving leaf or a small mouse. The sensitivity can be changed depending on the installation location and project specifications.

The second potentiometer is to specify the duration for which the detection output should be active. It can be programmed to turn on for as few as a few seconds or as long as a few minutes.

PIR sensors are used in thermal sensing applications such as security and motion detection. They're commonly found in security alarms, motion detection alarms, and automatic lighting applications.

SMTP

The simple mail transfer protocol (SMTP) is an internet standard for sending and receiving electronic mail (or email), with an SMTP server receiving emails from email clients.

SMTP is also used to establish server-to-server communication.

Gmail, Hotmail, Yahoo, and other email providers all have their own SMTP addresses and port numbers.

Fig. 3 SMTP

How does SMTP work?

To send emails, the SMTP protocol, also known as the push protocol, is used, and IMAP, or Internet Message Access Protocol (or post office protocol or POP), is used to receive emails at the receiver end.

The SMTP protocol operates at the application layer of the TCP/IP protocol suite.

When the client wants to send emails, a TCP connection to the SMTP server is established, and emails are sent over the connection.

SMTP commands:

• HELO – This command is sent only once per session and it is used to identify the qualified domain names and the client to the server.
• MAIL – used to initiate a message
• RCPT – Identifies the address
• DATA – This command is responsible for sharing data line by line

SMTP server parameters for email service

There are various email service providers available like, Gmail, Yahoo, Hotmail, Outlook etc. and each service provider have unique service parameters.

In this tutorial, we are using the Gmail or Google Mail service.

Gmail is the email service provided by Google and Gmail SMTP server is free to access and anyone can access this service, who has a Gmail account.

• SMTP server: smtp.gmail.com
• SMTP port: 465
• SMTP sender’s address: Gmail address
• SMTP sender's password: Gmail Password

Create a new Gmail account (Sender)

It is recommended to create a new email account for sending emails using ESP32 or ESP8266 modules.

If you are using your main (personal) email account (for sending emails) with ESP and by mistake something goes wrong in the ESP code or programming part, your email service provider can ban or disable your main (personal) email account.

In this tutorial we are using a Gmail account.

Follow the link to create a new Gmail account : https://accounts.google.com

Fig. 4 create new gmail account

Access to Less Secure apps

To get access to this new Gmail account, you need to enable Allow less secure apps and this will make you able to send emails. The link is attached below:

https://myaccount.google.com/lesssecureapps?pli=1

Fig. 5 permission to less secure apps

Interfacing ESP32 and HCSR-501

Table 1

Fig. 6 ESP32 and HCSR-501 connections

Arduino IDE Programming

We are using Arduino IDE to compile and upload code into ESP32 module. To know more about ESP32 basics, Arduino IDE and how to use it, follow our previous tutorial i.e., on ESP32 programming series. Link is given below:

https://www.theengineeringprojects.com/2021/11/introduction-to-esp32-programming-series.html

Necessary Library

To enable the email service in ESP32 it is required to download the ESP-Mail-Client Library. This library makes the ESP32 able to send email over SMTP server.

Follow the steps to install the ESP-Mail-Client library:

1. Go to the link and download the ESP-Mail-Client library:

https://github.com/mobizt/ESP-Mail-Client

2. Open your Arduino IDE.
3. Then to add the ZIP file go to Sketch >> Include Library >> Add.ZIP Library and select the downloaded ZIP file.

Fig. 7 Adding ESP-Mail-Client Library

4. Click on

Arduino IDE Code

//To use send Email for Gmail to port 465 (SSL), less secure app option should be enabled. https://myaccount.google.com/lesssecureapps?pli=1

//----Add the header files

#include <WiFi.h>

#include <ESP_Mail_Client.h>

//-----define network credentials

#define WIFI_SSID "public"

#define WIFI_PASSWORD "ESP32@123"

//--add the Server address and port number with respect to a particular email service provider

#define SMTP_HOST "smtp.gmail.com"

#define SMTP_PORT esp_mail_smtp_port_587 //port 465 is not available for Outlook.com

 

//----The log in credentials

#define AUTHOR_EMAIL "techeesp697@gmail.com"

#define AUTHOR_PASSWORD "Tech@ESP123"

//----The SMTP Session object used for Email sending

SMTPSession smtp;

//---Declare the message class

SMTP_Message message;

//---Callback function to get the Email sending status

void smtpCallback(SMTP_Status status);

const char rootCACert[] PROGMEM = "-----BEGIN CERTIFICATE-----\n"

"-----END CERTIFICATE-----\n";

int inputPin = 4; // connect with pir sensor pin

int pir_output = 0; // variable to store the output of PIR output

void setup()

{

pinMode(inputPin, INPUT);

pinMode(LED_BUILTIN, OUTPUT);

Serial.begin(115200);

pir_output = digitalRead(inputPin);

Serial.println();

Serial.print("Connecting to AP");

WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

while (WiFi.status() != WL_CONNECTED)

{

Serial.print(".");

delay(200);

}

Serial.println("");

Serial.println("WiFi connected.");

Serial.println("IP address: ");

Serial.println(WiFi.localIP());

Serial.println();

/** Enable the debug via Serial port

* none debug or 0

* basic debug or 1

*

* Debug port can be changed via ESP_MAIL_DEFAULT_DEBUG_PORT in ESP_Mail_FS.h

*/

smtp.debug(1);

/* Set the callback function to get the sending results */

smtp.callback(smtpCallback);

/* Declare the session config data */

ESP_Mail_Session session;

/* Set the session config */

session.server.host_name = SMTP_HOST;

session.server.port = SMTP_PORT;

session.login.email = AUTHOR_EMAIL;

session.login.password = AUTHOR_PASSWORD;

session.login.user_domain = "mydomain.net";

/* Set the NTP config time */

session.time.ntp_server = "pool.ntp.org,time.nist.gov";

session.time.gmt_offset = 3;

session.time.day_light_offset = 0;

/* Set the message headers */

message.sender.name = "ESP Mail";

message.sender.email = AUTHOR_EMAIL;

message.subject = "Email Alert on Motion detection";

message.addRecipient("Anonymous",

"replace this with receiver email adderss");

String textMsg = "Motion Detected!!!!!";

message.text.content = textMsg;

message.text.charSet = "us-ascii";

message.text.transfer_encoding = Content_Transfer_Encoding::enc_7bit;

message.priority = esp_mail_smtp_priority::esp_mail_smtp_priority_low;

/* Set the custom message header */

message.addHeader("Message-ID: <abcde.fghij@gmail.com>");

/* Connect to server with the session config */

if (!smtp.connect(&session))

return;

}

void loop()

{

if (pir_output == HIGH)

{

//----Start sending Email and close the session

if (!MailClient.sendMail(&smtp, &message))

Serial.println("Error sending Email, " + smtp.errorReason());

digitalWrite(LED_BUILTIN, HIGH);

Serial.println("Motion detected!");

Serial.println("Email sent");

}

else {

digitalWrite(LED_BUILTIN, LOW);

Serial.println("No Motion detected!");

}

delay(1000);

ESP_MAIL_PRINTF("Free Heap: %d\n", MailClient.getFreeHeap());

//to clear sending result log

smtp.sendingResult.clear();

}

/* Callback function to get the Email sending status */

void smtpCallback(SMTP_Status status)

{

/* Print the current status */

Serial.println(status.info());

/* Print the sending result */

if (status.success())

{

Serial.println("----------------");

ESP_MAIL_PRINTF("Message sent success: %d\n", status.completedCount());

ESP_MAIL_PRINTF("Message sent failled: %d\n", status.failedCount());

Serial.println("----------------\n");

struct tm dt;

for (size_t i = 0; i < smtp.sendingResult.size(); i++)

{

/* Get the result item */

SMTP_Result result = smtp.sendingResult.getItem(i);

time_t ts = (time_t)result.timestamp;

localtime_r(&ts, &dt);

ESP_MAIL_PRINTF("Message No: %d\n", i + 1);

ESP_MAIL_PRINTF("Status: %s\n", result.completed ? "success" : "failed");

ESP_MAIL_PRINTF("Date/Time: %d/%d/%d %d:%d:%d\n", dt.tm_year + 1900, dt.tm_mon + 1, dt.tm_mday, dt.tm_hour, dt.tm_min, dt.tm_sec);

ESP_MAIL_PRINTF("Recipient: %s\n", result.recipients);

ESP_MAIL_PRINTF("Subject: %s\n", result.subject);

}

Serial.println("----------------\n");

//You need to clear sending result as the memory usage will grow up as it keeps the status, timstamp and

//pointer to const char of recipients and subject that user assigned to the SMTP_Message object.

//Because of pointer to const char that stores instead of dynamic string, the subject and recipients value can be

//a garbage string (pointer points to undefind location) as SMTP_Message was declared as local variable or the value changed.

smtp.sendingResult.clear();

}

}

Note: The exact code cannot be used. As a result, before uploading the code, you must make some changes such as replacing the SSID and password with your network credentials, email address of sender and receiver, SMTP setting parameters for respective email service providers, and so on. We'll go over these details as well during the code description.

Code Description

• The first step is adding the required header files or libraries.
• Here we are using two libraries:
  • The first one is h, which is used to enable the Wi-Fi module and hence wireless network connectivity.
  • Another library file required is the h to enable email service over SMTP (simple mail transfer protocol).

Fig. 8

• Enter the network credentials in place of SSID and PASSWORD.

Fig. 9

• Enter the SMTP parameter of the respective email service provider like, Gmail, Yahoo, Outlook, Hotmail etc. (In this tutorial we are using Gmail service).
• Parameters used below are for Gmail.

Fig. 10

• Enter the sender’s email login details (email address and password ).

Fig. 11

• Insert recipient’s email address.

Fig. 12

• SMTPSession object is used for sending emails.

Fig. 13

• Next step is declaring a message

Fig. 14

• This smtpCallback() function is used to get the email sending status.

Fig. 15

• This function also includes printing the results like success and failure of email sent.

Fig. 16

• Next we are defining a variable to store the GPIO pin number to which the PIR sensor is to be connected.
• Next variable pir_output is used to store the current state of PIR output and initially it is fixed to zero.

Fig. 17 Variable for PIR sensor

Setup()

• Initialize the serial monitor at 115200 baud rate for debugging purpose.
• Set the mode as INPUT for the GPIO pin to which PIR module is to be connected i.e., GPIO 4.
• We are using the built-in LED (LED turns ON when a motion is detected.
• The digitalRead() function is used to read the output of PIR sensor module, by passing the GPIO pin (to which PIR sensor is connected) as an argument and results will be stored inside pir_output

Fig. 18

• begin() function is used to initialize the Wi-Fi module with Wi-Fi credentials used as arguments.
• The While loop will continuously run until the ESP32 is connected to Wi-Fi network.

Fig. 19

• If the device is connected to local Wi-Fi network then print the details on serial monitor.
• localIP() function is used to fetch the IP address.
• Print the IP address on serial monitor using println() function.

Fig. 20

• debug() is used to enable the debug via Serial port where ‘0’ and ‘1’ are used as arguments where;
  • 0 - none debug
  • 1 - basic debug

• Inside ESP_Mail_FS.h header file, ESP_MAIL_DEFAULT_DEBUG_PORT can be used to change the Debug port.
• Set the callback() function to get sending results.

Fig. 21

• Setting session configuration includes, assigning the server address, port number of the server (here we are using Gmail services), email login details of the sender etc.

Fig. 22

• Next step is setting the message header.
• Message header will be set inside the setup() function which includes, sender’s name, subject, sender’s email address, receiver’s email address and name.
• A string type variable textMsg is defined to to store the message to be transferred over email.

Fig. 23

• connect() function.is used to connect to server with session configuration.

Fig. 24

Loop

• ESP32 is continuously checking for the input from PIR sensor inside the loop function.
• If the input received from pir sensor is HIGH the ESP32 will generate an email to the client for that sendMail() function is used and if mail transmission is failed then that will be printed on the serial monitor along with the reason.
• The inbuilt LED on ESP32 will be turned ON and the respective results will be printed on the serial monitor.

Fig. 25 ‘If motion detected’

• If the input received from the PIR sensor is LOW then the LED will remain LOW/OFF and no email alert will be generated.

Fig. 25 No motion detected

• Finally, clear the email log to avoid excessive memory usage.

Fig. 26 Clear the email log

Testing

• Open the Arduino IDE.
• Paste the above code into your Arduino IDE.
• Make the required changes in the code like, network credentials, email service parameters of the respective email service provider, sender and receiver email address and define the message you want to share over SMTP server.
• Select the right development board and COM port for serial communication.

Fig. 27 select development board and COM port

• Compile and upload the program into the ESP32 development board.
• Connect the HCSR-501 module with the ESP32 as per the circuit/connect details given above.

Fig. 28 ESP32’s Inbuilt LED is turned ON when a motion is detected

• Open the serial monitor with 115200 baud rate.

Fig. 29 Serial monitor

• Check the receiver email account.

Fig.30 received email on motion detection

This concludes the tutorial. We hope you found this of some help and also hope to see you soon with a new tutorial on ESP32.

Motion Detection with ESP32 & PIR Sensor

Hello readers, we hope you all are doing great. Welcome to the 4th lecture of Section 5(ESP32 Sensor) in the ESP32 Programming Series. So far, we have discussed the ESP32 built-in sensors in this section. Today, we are going to interface an external embedded sensor(i.e. PIR Sensor) with the ESP32 Microcontroller board. At the start, we will discuss the basics of a PIR Sensor(HC-SR501) i.e. its pinout and working. After that, we will design a simple project to detect the motion with a PIR sensor and ESP32. Finally, we will display the motion detection results on the ESP32 WebServer.

We will use ESP32 interrupts to detect the motion. Interrupts are used when a microcontroller needs to continuously monitor an event while executing other tasks at the same time. We have already posted a tutorial on ESP32 Interrupts, which includes both software and hardware interrupts. In this tutorial, we are implementing the hardware interrupt(Hardware interrupts are the external interrupts that are caused by an external event). In our project, the hardware interrupt will be generated by the PIR sensor.

PIR motion sensor is mostly used in home automation & security projects, used to enable the system to respond automatically over human presence. Appliances connected to ESP32 will respond automatically(as per the instructions provided) whenever an interrupt is triggered by the PIR motion sensor. Let's first have a look at the working of PIR Sensor:

Where To Buy?
No.	Components	Distributor	Link To Buy
1	ESP32	Amazon	Buy Now

What is a PIR Motion Sensor?

In today's project, we will use the HC-SR501 PIR Sensor to detect the motion. PIR stands for Passive Infrared sensors. It uses a pair of pyroelectric sensors to detect heat energy in the surrounding environment. Both the sensors sit beside each other, and when a motion is detected or the signal differential between the two sensors changes the PIR motion sensor will return a LOW result (logic zero volts). It means that you must wait for the pin to go low in the code. When the pin goes low, the desired function can be called.

PIR Sensor Calibration

PIR Sensor has two variable resistors on its back side, used to adjust the Sensitivity and Detection Range, explained below:

• Low sensitivity ignores the small motions i.e. a moving leaf or a small mouse. The sensitivity can be adjusted based on the installation location and project requirements.
• The second resistor is used to specify how long the detection output should be active. It can be set to turn on for as little as a few seconds or as long as a few minutes.

PIR Sensor Applications

Thermal sensing applications, such as security and motion detection, make use of PIR sensors. They're frequently used in security alarms, motion detection alarms, and automatic lighting applications.

Now let's interface the PIR Sensor with ESP32:

Interfacing PIR Sensor with ESP32

As I mentioned earlier, in today's project, we will design a motion detection project with ESP32 and PIR Sensor. In the first example, we will turn "ON" the LED on motion detection, while in the second project, we will display the results in the ESP32 WebServer.

Here's the list of the components for today's project:

Components Required

• ESP32 Development Board
• PIR motion sensor (HC-SR501)
• LED
• 1k Ohm resistor
• Jumper Wires
• Breadboard

Circuit Diagram

Here's the circuit diagram for motion detection with ESP32 and PIR Sensor:

Now let's design the programming code for motion detection:

ESP32 Motion Detection Code

We are using Arduino IDE to compile and upload code into the ESP32 module. You need to first Install ESP32 in Arduino IDE to get started. Here's the code for motion detection:

//----Set GPIOs for LED and PIR Motion Sensor
const int led = 23;
const int PIRSensor = 4;

// -----Timer: Auxiliary variables
#define timeSeconds 10
unsigned long now = millis();
unsigned long lastTrigger = 0;
boolean startTimer = false;

//---Checks if motion was detected, sets LED HIGH and starts a timer
void IRAM_ATTR detectsMovement()
{
    Serial.println( " MOTION DETECTED " );
    Serial.println("Turning ON the LED");
    digitalWrite(led, HIGH);
    startTimer = true;
    lastTrigger = millis();
}

void setup()
{
    Serial.begin( 115200 ); // Serial port for debugging purposes
    pinMode( PIRSensor, INPUT_PULLUP ); // PIR Motion Sensor mode INPUT_PULLUP
    pinMode( led, OUTPUT );
    digitalWrite( led, LOW );
    attachInterrupt( digitalPinToInterrupt( PIRSensor ), detectsMovement, FALLING ); // Set PIRSensor pin as interrupt, assign interrupt function and set RISING mode
}

void loop()
{
    now = millis();
    if( startTimer && (now - lastTrigger > ( timeSeconds*500)))
    {
        Serial.println(" Turning OFF the LED " );
        digitalWrite( led, LOW );
        startTimer = false;
    }
}

Variables Declaration

• The first step is to set up the GPIO pins for the LED and motion sensor(PIR).
• LED is connected to GPIO23 and PIR sensor to GPIO4, as shown in the below code:
  

//----Set GPIOs for LED and PIR Motion Sensor
const int led = 23;
const int PIRSensor = 4;

• Next, we need variables to set the timer to count the time, after the interrupt is detected.
• The variable "now" defines the current time
• The variable "lastTrigger" defines the time when the interrupt is detected.
• The variable "startTimer" is used to start the time when an interrupt is detected.

//-----Timer: Auxiliary variables
#define timeSeconds 10
unsigned long now = millis();
unsigned long lastTrigger = 0;
boolean startTimer = false;

ESP32 Interrupt Function "IRAM_ATTR"

• The Function with the attribute "IRAM_ATTR" is executed inside the internal RAM.
• We are assigning this attribute to our interrupt function because RAM (random access memory) operates faster than flash memory.
• After the execution of the interrupt code or ISR, the normal code will be executed inside the flash memory.
• It is recommended that the interrupt service routine should have the minimum possible execution time because it halts or blocks the normal program execution.

//---Checks if motion was detected, sets LED HIGH and starts a timer
void IRAM_ATTR detectsMovement()
{
    Serial.println( " MOTION DETECTED " );
    Serial.println("Turning ON the LED");
    digitalWrite(led, HIGH);
    startTimer = true;
    lastTrigger = millis();
}

Setup() Function

• Inside the setup() function we are initializing the serial communication with a baud rate of 115200.
• Set the mode of pin GPIO23 (LED) as output.
• Set the initial state of the LED as LOW.
• Assigned the digital pin(connected to the PIR Sensor) to hardware interrupt using the attachInterrupt function.
• The detectMovement function is passed as an argument inside this function.

void setup()
{
    Serial.begin( 115200 ); // Serial port for debugging purposes
    pinMode( PIRSensor, INPUT_PULLUP ); // PIR Motion Sensor mode INPUT_PULLUP
    pinMode( led, OUTPUT );
    digitalWrite( led, LOW );
    attachInterrupt( digitalPinToInterrupt( PIRSensor ), detectsMovement, FALLING ); // Set PIRSensor pin as interrupt, assign interrupt function and set RISING mode
}

Loop() Function

We have activated the interrupt in the Setup Function, so when the PIR Sensor detects the motion, it will automatically execute the interrupt function, which will turn the LED ON and start the timer.

• In the loop function, we are comparing the current time with the last triggered time.
  
• LED will turn off after a delay of 5sec (once an interrupt is detected).
  
• The variable “now” will be updated with the current time in each iteration.

void loop()
{
    now = millis();
    if( startTimer && (now - lastTrigger > ( timeSeconds*500)))
    {
        Serial.println(" Turning OFF the LED " );
        digitalWrite( led, LOW );
        startTimer = false;
    }
}

Motion Detection Results/Testing

• Select the right development board from Tools >> Boards >> DOIT ESP32 DevKit V1 in Arduino IDE.
• Compile and upload the code into ESP32 using Arduino IDE.
• Open the serial monitor with a 115200 baud rate as defined in the Arduino code.
• Press the EN button on the ESP32 development board.

This concludes the tutorial. I hope you find this tutorial helpful. Thanks for reading. See you soon with a new tutorial on ESP32. Take care !!!