Embedded-Voting-Machine with Coupon Authentication and ThingSpeak Cloud Integration

This project implements a microcontroller-based Electronic Voting Machine (EVM) using an ESP32, I2C LCD, 4x4 keypad, and ThingSpeak for cloud-based vote tracking. The voting system supports unique coupon-based voter authentication to prevent duplicate voting. https://mehedi-hasan-soft-web-support.github.io/Embedded-Voting-Machine-with-Coupon-Authentication-and-ThingSpeak-Cloud-Integration/

🔧 Features

• Coupon code-based secure voting
• 3-tier voting (President, General Secretary, Vice President)
• Admin mode to view results and sync data
• Automatic reset after timeout
• Real-time cloud sync to ThingSpeak
• Voter input via 4x4 Matrix Keypad
• User feedback via 20x4 I2C LCD display

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📟 Hardware Components

Component	Quantity	Description
ESP32 Development Board	1	Main controller with WiFi capability
20x4 I2C LCD Display	1	Displays instructions, candidates, and results
4x4 Matrix Keypad	1	For user input and coupon code entry
Jumper Wires	Several	For connections
Breadboard (optional)	1	For prototyping
USB Cable	1	For ESP32 programming and power

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🔌 Circuit Diagram (Table View)

ESP32 GPIO Pin	Connected To	Component
GPIO 13	Row 1	Keypad
GPIO 12	Row 2	Keypad
GPIO 14	Row 3	Keypad
GPIO 27	Row 4	Keypad
GPIO 26	Col 1	Keypad
GPIO 25	Col 2	Keypad
GPIO 33	Col 3	Keypad
GPIO 32	Col 4	Keypad
GPIO 21 (SDA)	SDA	I2C LCD
GPIO 22 (SCL)	SCL	I2C LCD
3.3V	VCC	I2C LCD & Keypad
GND	GND	I2C LCD & Keypad

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🚦 Voting Flow

1. Welcome Screen: Voter is prompted to press 1 to vote or * to enter admin mode.
2. Coupon Entry: Voter inputs a unique code and confirms with #.
3. Voting Stages: Voter votes for:
   • President
   • General Secretary
   • Vice President
4. Confirmation: Voter reviews and confirms vote.
5. Cloud Sync: Votes are sent to ThingSpeak channel.

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🔑 Admin Mode

Accessed by pressing * on the welcome screen.

• Press 1 to display local results
• Press 2 to manually sync data with ThingSpeak
• Press # to exit admin mode

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☁️ ThingSpeak Configuration

• Create a channel with at least 6 fields (one per candidate).
• Replace your API Key and Channel ID in the code.

const char* server = "api.thingspeak.com";
String writeAPIKey = "YOUR_API_KEY_HERE";
unsigned long channelID = YOUR_CHANNEL_ID;