Project Hub /Basic Analog & Power Electronics/Make Your Own Group Messenger

Intermediate

OTHER CONTROLLER

₹1,500 – ₹5,000

6 – 12 Hours

Partial Kit

Make Your Own Group Messenger

Build a custom wireless group messenger system utilizing an ATmega32 microcontroller and an HC-12 wireless transceiver to send and display keyword messages.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
2-Slot 18650 Holder with Protective Cover and On/Off Switch – Case Rs. 109.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: LCD (generic / unspecified)
Battery (generic / unspecified)
ATmega / AVR chip
RTC Module DS3231 / DS1307
Voltage Regulator IC (7805 / LM317 / 1117)
Custom PCB / PCB Fab
9V Battery + Snap
Long-range wireless transceiver
SS1 through SS8)

Browse all components

How It Works

The Make Your Own Group Messenger is an embedded wireless communication system built around an AVR ATmega32 microcontroller. The central processing unit coordinates user inputs, manages local timekeeping, and drives display output while communicating over the air via an HC-12 long-range wireless transceiver. Power management is handled by a 7805 5V regulator IC, which steps down the voltage from an external 9V or 12V DC power adaptor or battery to a safe operating level for the digital logic and peripherals. A power switch (S1) controls the main power rail, while a dedicated Power LED indicates active status. User interaction is facilitated through a matrix of push switches, designated as ES1 through ES5 and SS1 through SS8, allowing operators to compose and select keyword messages or navigate menus. Real-time tracking is managed by a DS1307 Real Time Clock IC, backed by a 3V coin cell battery and holder to maintain time data when main power is disconnected; a seconds LED (LED4) provides a visual heartbeat of the clock's operation. Message composition, status, and system data are presented visually on an LCD display (LCD1). Current-limiting resistors, including a 470-ohm resistor designated as R28, protect indicator LEDs and interface lines. Shorting jumpers (SJ1, SJ2, SJ3) allow for hardware configuration options on the custom PCB layout, which ties all components together with connecting wires.

Why Build This

Deploy a self-contained, local wireless communication network for small engineering teams, offices, or labs without relying on internet infrastructure.

Gain practical experience designing embedded systems that integrate asynchronous serial wireless transceivers with microcontroller firmware.

Implement time-stamping and user-interface peripherals like real-time clock ICs and tactile switch matrices in a single hardware platform.

Real-World Application

Useful for small teams, offices, or closed environments where quick status updates or short keyword-based messages can be transmitted wirelessly without internet access.

Skills You'll Learn

Microcontroller firmware design

UART serial communication with wireless transceivers

I2C protocol interfacing with real-time clock modules

LCD character display driving

switch matrix scanning and debouncing

power supply regulation and circuit protection

Safety Precautions

Ensure correct polarity when connecting the 9V or 12V DC power supply to prevent damage to the voltage regulator and ICs.

Frequently Asked Questions

Why is a 7805 voltage regulator required in this circuit?

The 7805 steps down the higher input voltage (9V or 12V DC) to a stable 5V supply required by the ATmega32 microcontroller, HC-12 transceiver, and LCD display, protecting sensitive logic components from overvoltage.

What is the purpose of the 3V coin cell battery if the system uses an external power supply?

The 3V coin cell acts as a backup power source exclusively for the DS1307 Real Time Clock IC, ensuring that time data is not lost when the main 9V/12V power adapter is switched off or disconnected.

How do the HC-12 transceivers communicate with the ATmega32?

The HC-12 typically communicates via UART serial interface, allowing the ATmega32 to send and receive text data wirelessly over long ranges using standard serial transmission protocols.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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