# Zephyr UART + LED - Nucleo G474RE

A learning project for [Zephyr RTOS](https://zephyrproject.org/) targeting the **STM32 Nucleo G474RE** dev board! I have always seen Zephyr projects in the wild and want to document my learning process. I've used FreeRTOS in the past and want to rewrite some projects using Zephyr 🙂

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## Hardware

| | |
|---|---|
| **Board** | ST Nucleo G474RE |
| **MCU** | STM32G474RE (ARM Cortex-M4F, 170 MHz) |
| **UART** | LPUART1 via onboard ST-Link VCP (PA2/PA3) |
| **LED** | LD2 on PA5 |

Connect via USB to the Nucleo's ST-Link port

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## Features

- **Interrupt-driven UART RX** - ISR writes bytes into a ring buffer
- **Dedicated RX thread** - sleeps on a semaphore, wakes on data arrival
- **Line accumulation** - buffers input until `\r` or `\n`
- **Formatted output** - prints received line with length and uptime timestamp
- **LED** - on PA5 configured via devicetree overlay (for testing)

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## Getting Started

### Prerequisites

- [Zephyr SDK](https://docs.zephyrproject.org/latest/develop/getting_started/index.html) installed
- `west` installed and workspace initialized

### Build & Flash

```bash
west build          # board is set in CMakeLists.txt
west flash

(optionally)
west debug
```

### Serial Monitor

Connect a terminal to the ST-Link Virtual COM Port at a baud rate of **115200**:

Personally, I just use PuTTY!

Type a line and press Enter:

```
─────────────────────────────
│ RX: hello
│ Len: 5,   Time: 6741
─────────────────────────────
```

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## License

[Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0)