Biometric Attendance System – STM32F401 + GT-521F32

This repository contains a biometric attendance system built on the Raayan Mini (STM32F401RBT6) board.
It uses a GT-521F32 fingerprint sensor over UART, a 16×2 character LCD, a 4×4 matrix keypad, and a few switches to provide User and Admin modes.

The code is written in bare-metal C and targets Keil µVision (MDK-ARM).

Features

• Fingerprint-based attendance
  • GT-521F32 sensor connected to USART1 (PA9/PA10)
• Two operating modes
  • User mode – mark attendance with fingerprint
  • Admin mode – manage users via keypad and LCD
• Interrupt-based inputs
  • Touch input (sensor wake/LED control)
  • Mode selection switches on EXTI lines
• 16×2 LCD user interface
  • Status messages, prompts, and simple feedback
• 4×4 keypad support
  • Numeric and basic menu inputs

Hardware

• Raayan Mini board (STM32F401RBT6, Cortex-M4)
• GT-521F32 fingerprint sensor module
• 16×2 character LCD (HD44780-compatible)
• 4×4 matrix keypad
• Two push-buttons for DOWN and ENTER
• ST-Link V2 debugger/programmer
• External 5 V / 3.3 V supply as per board requirements

Pin Configuration

Function	Peripheral / Signal	MCU Pin	Port	Notes
Fingerprint UART TX (MCU → FP)	USART1_TX	PA9	A	Connect to GT-521F32 RX
Fingerprint UART RX (FP → MCU)	USART1_RX	PA10	A	Connect to GT-521F32 TX
Fingerprint touch input	EXTI line 6	PA6	A	Rising/falling edge, controls CMOS LED
Keypad row 0	GPIO output	PC0	C	Row lines: PC0–PC3
Keypad row 1	GPIO output	PC1	C
Keypad row 2	GPIO output	PC2	C
Keypad row 3	GPIO output	PC3	C
Keypad column 0	GPIO input (pull-down)	PC4	C	Column lines: PC4, PC5, PC11, PC12
Keypad column 1	GPIO input (pull-down)	PC5	C
Keypad column 2	GPIO input (pull-down)	PC11	C
Keypad column 3	GPIO input (pull-down)	PC12	C
DOWN switch	EXTI line 9	PC9	C	Triggers User mode
ENTER switch	EXTI line 10	PC10	C	Triggers Admin mode
LCD data bus (4-bit mode)	D4–D7	PB0–PB3	B	High and low nibble sent on PB0–PB3
LCD RS	Register Select	PB4	B	0 = command, 1 = data
LCD RW	Read/Write	PB5	B	0 = write (used), 1 = read (optional)
LCD EN	Enable strobe	PB8	B	Rising edge latch

If your board revision uses different pins, please update the corresponding GPIO/EXTI configuration functions.

Project Structure

• Src/
  • BAS_using_GT521F32.c / main.c – main application and mode control
  • FP_gt521f32.c – GT-521F32 sensor driver and command handling
  • UART1.c – USART1 init/config and send/receive helpers
  • km_lcd.c – 16×2 LCD driver in 4-bit mode
  • 4x4_keypad.c – keypad init and scanning
  • Interrupt.c – EXTI configuration and NVIC setup
  • systemticktimer.c – SysTick-based millisecond delays
  • gpio.c, my_string.c – basic GPIO and utility functions

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Build & Run (Keil µVision)

1. Download the repository as .zip
2. Extract the .zip file
3. Open the project .uvprojx file in Keil µVision.
4. Select the target for STM32F401RBT6 / Raayan Mini.
5. Build the project (F7).
6. Connect the board via ST-Link V2.
7. Flash the firmware (Ctrl + F8) and reset the board.

On startup, the firmware initializes USART1, LCD, keypad, SysTick, and interrupts, then waits for:

• DOWN (PC9) → enter User mode and capture attendance.
• ENTER (PC10) → enter Admin mode for management via keypad.

📸 Demo

🎥 Click the image to watch the Smart Weather Monitor System in action!