UART RX/TX Driver Example for STM32F4

This repository contains a simple UART (Universal Asynchronous Receiver/Transmitter) driver for the STM32F4 microcontroller. The project demonstrates basic UART receive (RX) and transmit (TX) functionality and uses UART input to control an onboard LED.

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📁 Project Files

File	Description
uart.c	UART driver implementation
uart.h	UART driver API/header
main.c	Main program using UART and GPIO logic

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🔌 Hardware and Pin Configuration

STM32F4 Pins Used

Peripheral	Pin	Function	Description
UART2	PA2	TX (AF7)	Transmits UART data
UART2	PA3	RX (AF7)	Receives UART data
GPIOA	PA5	Output	Controls the onboard user LED

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⚙️ Configuration Details

UART2 Pin Setup

• PA2: Configured as alternate function AF7 for UART2 TX
• PA3: Configured as alternate function AF7 for UART2 RX
• Alternate functions are set in UART2_RXTX_INIT() in uart.c

LED Pin Setup

• PA5: Configured as output
• Receiving character '1' over UART turns the LED ON
• Any other character turns the LED OFF

UART Parameters

Parameter	Value
Baud Rate	115200
Data Bits	8
Stop Bits	1
Parity	None
Flow Control	None

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🧠 How the Code Works

1. Initialization

• UART2 is initialized with the above parameters
• GPIOA clock is enabled
• PA2, PA3 set as alternate function for UART
• PA5 is set as output for LED control

2. Main Loop Operation

• Continuously waits for a character from UART2
• If received character is '1', sets PA5 HIGH (LED ON)
• Otherwise, sets PA5 LOW (LED OFF)

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▶️ Using the Example

Requirements

• Hardware: STM32F4 Discovery board (or compatible)
• Software: STM32CubeIDE, Keil uVision, or any ARM GCC toolchain
• Serial Terminal: PuTTY, Tera Term, Minicom, etc.

Serial Terminal Settings

Setting	Value
Baud Rate	115200
Data Bits	8
Stop Bits	1
Parity	None
Flow Ctrl	None

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🔁 Flashing & Testing Instructions

1. Copy uart.c, uart.h, and main.c into your STM32 project
2. Compile and upload the code to your STM32F4 board
3. Connect UART2 pins:
   • PA2 (TX) → Connect to RX of USB-to-Serial adapter
   • PA3 (RX) → Connect to TX of USB-to-Serial adapter
4. Open your serial terminal and apply the settings above
5. Send:
   • '1' → LED ON
   • Any other key → LED OFF

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📌 Code Structure Highlights

• Proper initialization of GPIO and UART pin modes
• Baud rate calculations based on 16 MHz system clock
  (⚠️ Adjust if your board uses a different clock)
• Low-level register operations are commented for clarity

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