Several applications of IoT require basic components and internet connection. In this chapter, the components of the system and the block diagram structure are presented, including the process of controlling and monitoring the system within IoT.

The system’s block diagram is shown in Figure 1 . The lock is controlled by the microcontroller that is connected to fingerprint, keypad and camera. This type of controller has the ability to connect to internet and send data to a certain server. The user can have control of the microcontroller through an application.

The diagram block of the system was designed based on putting the controller in the middle, and then the controller was connected to the server by a WIFI router, and then the user was connected to the controller through Biometric Door Lock such as fingerprint machine or password..etc. Accordingly, we can get closed loop.

In this study, ESP32 WROOM Module is chosen (specifications shown in Table 1 ), as shown in Figure 2 . This chip is called “The chip of the future”, and it is widely used in IoT applications and projects. It has several advantages such as built-in Wi-Fi and Bluetooth, many pins for input and output, and 10 touch sensors that can be used in different applications. It is programmed by Arduino software IDE.

Why do we use ESP 32 Series of microcontrollers?

The ESP32 Series of microcontrollers is the most popular among its siblings. They boast an extensive range of features: Dual-Core Processor, Wireless Connectivity, Low-Power Modes, Rich Peripherals, Analog-to-Digital Conversion

(ADC), Secure Boot and Flash Encryption, Support for Various Protocols, Extensive Memory, RTOS Support, OTA (Over-The-Air) Updates, Bluetooth Audio and Classic Bluetooth, Rich Development Ecosystem and Cost-Effective that is making it accessible to hobbyists and professionals alike “this feature is applicable also on ESP32 Camera”.

In addition, THE ESP32 Development tools and frameworks are ESP-IDF (Espressif IoT Development Framework) is the official software development framework for Espressif’s series of microcontrollers. It provides a comprehensive set of libraries, tools, and documentation for developing applications on these chips.

ESP-IDF is designed to make it easier for developers to harness the full potential of the ESP32 microcontroller and build a wide range of IoT and embedded applications. [3]

Note: The 5 V pin can be supplied with a Regulated 5 V, this voltage will again be regulated to 3.3 V through the on-board voltage regulator. Remember ESP32 operated with 3.3 V only.

With ESP32-CAM (specifications shown in Table 2 ), this chip is from ESP32 module family, it has fewer GPIOs than the ESP-32, because many of the GPIOs are used internally for the camera and the microSD card port. Figure 3 shows how it looks. Its main focus is on IoT projects and systems, this board allows you to create a localhost server for video steaming with a lot of resolutions, with external storage micro-SD card slot up to 4 GB with advanced functions like image tracking, and the camera is OV2640 module 2 MP.

In this project, we will use it as a second microcontroller, and it allows us to have visual feedback in case of incorrect entry of the system.

In this system, there are different platforms in order to view the data the captured Images:

Telegram ( Figure 4 ):

Using the telegram bot, we can also view the captured images from the ESP32-CAM microcontroller. All you need is to have a telegram account which can be created very easily and for free on your smart phone.

In this system, the Blynk applications will be chosen. This platform main focus is about IoT application. It allows the user to control and interact with different microcontrollers like Arduino, NodeMCU, ESP32, etc. in different ways, like, Bluetooth, USB, etc. The important one is via Wi-Fi [5] . With Blynk, we have the ability to control the system through your mobile.

Every person has unique friction ridges on their fingers, known as fingerprints. A fingerprint scanner is a hardware sensor that reads these unique fingerprints to verify a person’s identity. It is used to unlock content or services and is now common in smartphones and laptops. Figure 6 illustrates how a human fingerprint is converted into digital code.

The optical scanner, capacitive scanner, and ultrasonic scanner are the three common types of fingerprint scanners. Each type of scanner’s basic purpose is to image a picture of a person’s fingerprint and look for a match in its database. The accuracy of a fingerprint image is measured in dots per inch (DPI). Figure 7 shows the optical fingerprint scanner that will be used and Table 3 shows the Optical Fingerprint Scanner Specifications. [6]

In this system, the electric solenoid lock ( Figure 8 ) is chosen for locking mechanism. It is simple to install an electric door lock with only two weirs to be connected with the system. Table 4 shows the specifications of the electric solenoid lock.

A keypad is simply a group of buttons or switches, we can call them the keypad elements. Each element represents a single value assigned to it inside the program by the programmer. Keypads come in different dimensions, sizes, and shapes like 1 × 4, 3 × 4, etc. Figures below show the internal structure of 4 * 4 keypad sizes.

A 4 × 3 Keypad Membrane module ( Figure 10 ) is chosen in this system in order to enter the code used to open the lock. Two buttons in this keypad are customized by programming to do specific things that will be discussed in next chapter ( Table 5 , Membrane Keypads Specifications).

12 V 4000 mAh rechargeable LITHIUM-ION battery ( Table 6 shows the specifications of LITHIUM-ION Battery) with charger is chosen to supply the solenoid lock circuit and the whole system in when main power failure.

This relay is used to switch from main power supply to the battery in case of main power failure. Table 7 shows the 12 V DC Omron relay 8PIN DPDT specification.

This adapter is used to power the whole system from the socket and Table 8 shows the specification of adapter 12 V 2 A Power Supply.

1) Magnetic Switch ( Figure 14 ):

This switch is used to indicate the status of the door if it’s closed or opened.

2) Push Button ( Figure 15 ):

This button is used to open the lock from inside the door.

3) Voltage Regulator ( Figure 16 ):

In order to operate the microcontrollers and components, we need this device to have 5 V for both ESP32-CAM and ESP32 for operation. This device makes the 12 V supplied from battery into 5-volt which is suitable for the needed devices ( Table 9 , 7805 Voltage Regulator Specification).

4) OLED Screen ( Figure 17 ):

Used to show specific words during operation of the system ( Table 10 shows OLED Screen Specifications).

5) Voltage Indicator ( Figure 18 ):

Used to show the battery voltage as an indicator

6) Small Components to be used:

Since design and product development are constantly looking for ways to improve human and consumer needs, the user may choose the cheapest and most functional product among competing products. The table below shows the estimated product prices; it can be said that 125 JOD is a reasonable price and competitive between other products mentioned before ( Table 11 shows the prices of the total components).

As previously mentioned, the ESP32 microcontrollers are widely used in IoT applications. They are easy to use, powerful, with many new features that usual microcontrollers do not have.

As the system starts in operation, first it will search for an internet connection, if there is an internet, it will complete its whole operation based on that, i.e., it will work on online mode, connection if not, it will work on offline mode. It should be noted that it will always search for internet connection.

If the system is connected to the Wi-Fi, first it will print on serial monitor that it’s connected to the Wi-Fi then connecting to Blynk application and a message will be shown on the application that is connected. [7]

Then the ESP32 will check if the system is closed, if it’s closed then also a message will be shown on Blynk “the door is closed. Then ESP32 will check if a push button is pushed (opened from inside) or not, if not the door will be closed. Other way it will be opened and a message will be shown on Blynk that it’s opened.

If the user placed his fingerprint on the scanner and matched the data that was already stored, the door will be opened and a message on app shows that it’s opened as well as the OLED screen will show (Door is Open)

If did not match, ESP32-Cam will take a photo and send it to the Telegram application and OLED shows (No Match!). It must be known that the default way of entering is by fingerprint.

If the user pressed the * key, its convert to the keypad, then a LED is turned on and a new PIN number is generated and sent to the Blynk (4 digits). The (#) is used to delete any entered digit, i.e., acts like backspace. If the PIN number is matched, the door is opened and OLED screen shows that also, if not a photo is taken and sent to Telegram application while OLED screen shows (Wrong Pin!).

In Online Mode, different commands can be done with Blynk application on the system operation like as shown in Figure 23 : [8]

If the system fails to connect to the Wi-Fi, it will be in offline mode operation, and it has less status.

If the user placed his fingerprint on the scanner and matched the data that was already stored, the door will be opened, and OLED screen will show (Door is Open).

If not, the OLED screen shows (No Match!), and the door is still locked.

If the user pressed the * key, it convert to the keypad, then a LED is turned on and the user should enter the default PIN which is (4 digits). While having the ability to delete the entered digit by (#) button. If the PIN number isn’t matched, (Wrong Pin!) is shown on the OLED screen.

If the door was opened by unusual way i.e., not by the mentioned ways, The system takes a photo and be sent to the application.

The ESP32 in this state, is in sleep mode while ESP32-CAM is on.

The mentioned controllers are to heart of the system, and as long as the system has an internet access, ESP32 is connected with the Blynk application, while being ESP32-Cam connected with Telegram.

With the help of IoT and its advantages, and in the online modes, our system deals with sending the captured photos through the API and sent to a server from telegram which is specific to IoT applications. It should be noted that the picture is very fast when being taken and sent, not a considerable delay. Figure 24 below shows the captured images and being shown on the phone.

As the whole system is being controlled by this microcontroller, it’s also being controlled with the phone application Blynk, as long as it’s s in online mode, and by meaning controlled, we can open the lock by using this application. In our system, we have a feature which is reports, the function of reports widget is to configure and customize data reports in CSV format, i.e., we have the ability to know when the door was opened in the mentioned format. i.e., shows the status history of the lock. It is also possible to be sent to your email and downloaded as an Excel sheet with time and date of the opening times as shown in Figure 25 .

Figure 26 below shows how would the Physical Connection be like, it can be seen that the ESP32 is connected to all the other components while having 3 connected lines with ESP32-CAM for different purposes:

1) ESP32 makes the ESP32-CAM take a photo and be sent to Telegram.

2) Face detection and recognition (Future Works).

3) The result of Face detection and recognition, if there is a matching, tells the ESP32 to open the lock.

Proteus software is used to implement the architecture outlined in the earlier pages for more analysis. Figures below show the implementation of the two microcontrollers ESP32-Cam ( Figure 27 ) & ESP32 in Proteus program ( Figure 28 ). As mentioned before, child sheet method is used in Proteus due to missing library of microcontrollers.

Figure 29 below shows the overall system simulation using Proteus software. Unfortunately, ESP32 and ESP32-CAM do not have a library and a child sheet method is used in order to make them act like an Arduino. Also, the fingerprint as well as soloed lock are having the same problem and cannot be dealt with the previous method.