STM32 Smart Factory Access Control System

A complete employee access control system built with STM32F401RE featuring biometric touch sensor, keypad authentication, and visual feedback.

Features

• 🔐 Secure Access Control - Employee ID validation with authorized personnel database
• 📱 1.8" TFT Display - Real-time visual feedback with ST7735 driver
• ⌨️ 4x3 Matrix Keypad - Numeric ID entry with # to submit, * to clear
• 👆 Touch Sensor - Capacitive touch activation
• 🚨 Audio Alerts - Different buzzer patterns for granted/denied access
• 💡 LED Indicators - Green LED for access granted
• 🔓 Relay Control - Automatic door lock/unlock (10-second timer)
• 🚫 Security Alert - Continuous buzzer alarm for unauthorized access attempts

Hardware Requirements

• MCU: STM32 Nucleo-F401RE
• Display: 1.8" TFT LCD (128x160) ST7735 via SPI1
• Keypad: 4x3 Matrix Keypad
• Touch Sensor: Capacitive touch sensor (PC8)
• LED: Green LED with 220Ω resistor (PC1)
• Buzzer: Active buzzer (PA4)
• Relay: 5V relay module for door lock (PB12)

Pin Configuration

Display (ST7735 - SPI1)

• CS: PB6
• DC: PA9
• RST: PC7
• SCK: PA5 (SPI1_SCK)
• MOSI: PA7 (SPI1_MOSI)

Keypad (4x3 Matrix)

• Rows (Output): R1=PA10, R2=PB15, R3=PB14, R4=PB13
• Cols (Input): C1=PB3, C2=PC4, C3=PB5

Other Peripherals

• Touch Sensor: PC8 (Input with pull-down)
• Green LED: PC1 (Output)
• Buzzer: PA4 (Output)
• Relay: PB12 (Output)

Authorized Employees

Employee ID	Name
1234	ADI
2005	GREY
2000	DEX

System Workflow

1. Idle State: Display shows "TOUCH SENSOR TO START"
2. Touch Activation: User touches capacitive sensor
3. ID Entry: Enter employee ID using keypad (0-9)
   • Press # to submit
   • Press * to clear entry
4. Verification: System validates ID against database
5. Access Granted (Valid ID):
   • Green screen: "WELCOME [NAME]"
   • Green LED turns ON
   • 1-second buzzer beep
   • Relay unlocks door
   • Door remains unlocked for 10 seconds
   • Returns to idle state
6. Access Denied (Invalid ID):
   • Red screen: "ACCESS DENIED"
   • Continuous buzzer alarm (until reset)
   • Door remains locked

Software Architecture

Core/
├── Inc/
│   ├── buzzer.h           - Buzzer control
│   ├── display_st7735.h   - ST7735 TFT driver
│   ├── keypad.h           - 4x3 keypad scanner
│   ├── led.h              - LED control
│   ├── relay.h            - Relay control
│   ├── simple_text.h      - Text rendering
│   ├── system_state.h     - State machine
│   └── touch.h            - Touch sensor
└── Src/
    ├── buzzer.c
    ├── display_st7735.c
    ├── keypad.c
    ├── led.c
    ├── main.c             - Main program
    ├── relay.c
    ├── simple_text.c
    ├── system_state.c     - Core logic
    └── touch.c

Building and Flashing

1. Open project in STM32CubeIDE
2. Build: Project → Build All (Ctrl+B)
3. Flash: Run → Debug (F11)

State Machine

• STATE_IDLE: Waiting for touch sensor activation
• STATE_WAIT_ID: Accepting keypad input
• STATE_VERIFY: Validating employee ID
• STATE_UNLOCK: Door unlocked, access granted

Customization

Adding New Employees

Edit Core/Src/system_state.c:

static const Employee_t employees[] = {
    {"1234", "ADI"},
    {"2005", "GREY"},
    {"2000", "DEX"},
    {"YOUR_ID", "YOUR_NAME"}  // Add here
};

Changing Door Unlock Duration

Edit Core/Src/system_state.c:

// Wait 10 seconds (change to desired duration in milliseconds)
while (HAL_GetTick() - unlock_timer < 10000) {

Security Features

• ✅ Employee ID validation
• ✅ Visual feedback for all states
• ✅ Audio alerts for access attempts
• ✅ Continuous alarm for unauthorized access
• ✅ Automatic door re-lock after timeout
• ✅ Touch sensor activation prevents accidental triggers

Future Enhancements

• RTC for timestamp logging
• SD card for access log storage
• WiFi connectivity (ESP32 integration)
• RFID card reader support
• Fingerprint sensor integration
• Web dashboard for monitoring
• Email/SMS notifications

License

MIT License - Feel free to use and modify for your projects!

Author

Built with ❤️ for factory security and access control applications

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