The Walkie Talkie With Print Verification project is a fully digital, hardware-secured wireless communication terminal. Unlike a classic radio station, the device allows real-time voice capture, P2P transmission, and playback only if the user passes a biometric authentication filter. The system integrates a permission-based access hierarchy (Admin vs. User) and is controlled by an ESP32 microcontroller.

What is its purpose: The main goal is to build a robust physical product, a sort of industrial prototype, capable of combining modern access control technologies (fingerprint sensor) with high-fidelity digital audio processing. At a technical level, the project demonstrates mastery of microcontroller architectures through the simultaneous integration of several studied complex protocols (UART, I2C, I2S) and the efficient use of hardware interrupts for the system's state machine.

What was the starting idea: The idea stemmed from the main vulnerability of conventional analog radio stations: lack of security. Anyone owning a station on the same frequency can listen or transmit. I thought about how I could implement a fundamental principle of cybersecurity (*Access Control* based on “Something you are”) directly into the physical environment, transforming a simple communication station into a strictly restricted data terminal.

To illustrate the architecture of the Walkie-Talkie with Print Verification, I have created a block diagram highlighting the hardware components and the data flow (communication protocols) between the peripherals and the central processing unit.

The Walkie-Talkie supports two types of users: Admin and General User.

• The Admin fingerprint is permanently stored and cannot be modified or overwritten.
• Only the Admin has the authority to enroll or remove a General User's fingerprint.
• Add User: The Admin authenticates by scanning their fingerprint, presses the action button briefly, and then the new user introduces their fingerprint.
• Remove User: The Admin authenticates and long-presses the action button for 5 seconds to wipe the General User from the database.

The OLED screen acts as the main interface, displaying the current communication status. During an incoming wireless transmission, an 'Incoming Transmission' message is shown on the screen.

If the device is unlocked (a user is logged in), the incoming audio is actively played through the speaker. Once authenticated, the user can receive and transmit freely for a 2-minute session before the system automatically times out, locks itself, and requires re-authentication.

The reset button must be held for 5 seconds to perform a full reset of the system. The user data is lost upon resetting.

Description: The hardware architecture centers on the ESP32, managing biometric security via UART and real-time audio through the I2S protocol. Digital peripherals (INMP441 and MAX98357A) ensure high-fidelity communication, while the OLED display and tactile buttons provide a responsive user interface for secure, peer-to-peer wireless transmission.

TBD

TBD

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