Wiznet makers

🧠 STM32 + W5500 Ethernet – TCP Server with FreeRTOS

This tutorial shows how to build a TCP server on an WIZnet W5500 Ethernet module paired with an STMicroelectronics STM32 microcontroller, and then integrate it into a real-time multitasking environment using FreeRTOS. The goal is to move beyond simple blocking mode networking and create a more responsive embedded system.

🔍 What the tutorial covers

Setup of the W5500 Ethernet module via SPI with an STM32 board.

Implementation of a TCP server using the W5500 hardware sockets (listen, accept connection, receive data, send data).

Initialization of FreeRTOS tasks, so that the networking task runs in one task, and other tasks (e.g., LED blinking, sensor reads) can run concurrently.

Handling of client data in a task context, while other tasks remain active — showing how a network interface can be incorporated into a multitasking system.

Discussion of performance considerations such as blocking vs non-blocking modes, task priorities, stack sizing, and which task handles socket operations.

📋 Why this matters for makers

If you’re designing an embedded device that needs reliable wired networking and should continue to perform other tasks (e.g., sensor measurement, actuator control, UI updates) while the network is idle or waiting, this tutorial is highly relevant. By combining STM32 + W5500 + FreeRTOS, you get the benefit of W5500’s hardware-based TCP/IP stack (reducing load on the MCU) together with a real-time OS to manage tasks cleanly and robustly.

🧩 Basic workflow outline

Wire up the SPI interface between STM32 and W5500: MOSI/MISO/SCLK/CS + RESET and power/GND.

Configure the MCU (SPI peripheral, GPIOs, clock) and initialize the W5500 (MAC address, IP settings or DHCP).

Create a FreeRTOS task (e.g., NetworkTask) which opens a socket in TCP mode, binds to a port, listens for client, and executes recv() / send() inside the task context.

Create other FreeRTOS tasks (e.g., LEDTask, SensorTask) that continue to operate regardless of network activity.

Use task synchronization or queues if required (for example, when received data triggers other tasks or hardware actions).

Monitor system behavior: ensure network task does not block other tasks, adjust task priorities if needed, verify socket closure/reopen logic for robustness.

✅ Strengths & ⚠️ Considerations

Strengths:

Demonstrates a real-world networking + RTOS use-case on cost-effective MCU + Ethernet module.

W5500 off-loads TCP/IP handling from STM32, freeing resources for other tasks.

FreeRTOS enables concurrent processing — critical for complex embedded applications.

Considerations:

Task stack sizing matters: network operations may require larger stacks than simple tasks.

Socket handling inside tasks must ensure correct re-initialization on client disconnects.

Blocking calls inside tasks can still hinder responsiveness if not designed carefully — in some cases non-blocking or callback/interrupt approaches may be needed.

If multiple sockets or high throughput is required, ensure W5500 socket usage is aligned with your FreeRTOS task design and system timing.

Created by: the author at ControllersTech

⚠️ Disclaimer: This tutorial was developed and published by ControllersTech. We are featuring it here to inform and inspire the maker community. All credit belongs to the original author, and we do not claim ownership or rights over this content.