Wiznet makers

Zephyr RTOS Receives Community Contribution for Full WIZnet W5500 TOE Support

Introduction

The Zephyr RTOS ecosystem continues to expand rapidly, driven by one of the most active open-source communities in embedded systems today. Zephyr has evolved from a small RTOS into a global, industry-supported platform, now backed by companies like Intel, Google, Nordic, NXP, Meta, and many more.

With over 1,500 active contributors per year and an estimated hundreds of thousands of engineers using Zephyr globally, the project is growing into a key infrastructure layer for IoT, consumer electronics, and industrial devices.

A recent example of this momentum is a community pull request adding true TOE (TCP/IP Offload Engine) support for the WIZnet W5500 Ethernet controller. This update moves far beyond the existing MACRAW-only implementation and brings Zephyr closer to fully leveraging WIZnet’s hardware networking capabilities.

Before continuing, this is important to state clearly:
👉 This project is not created by WIZnet, and WIZnet does not claim any ownership or rights to it.
We are simply highlighting meaningful community work that benefits developers using WIZnet solutions.

Zephyr — A Fast-Growing Platform Shaping the Future of Connected Devices

Zephyr is one of the most active RTOS projects ever created. Some key indicators of its growth:

• 1,500+ active developers annually
• 25,000+ total contributors since launch
• Hundreds of supported boards across every major MCU vendor
• Millions of downstream devices believed to ship with Zephyr-based firmware
• Ranked as a top Linux Foundation project in commit activity

As Zephyr gains traction in commercial IoT, industrial connectivity, and wearable devices, hardware vendors benefit from integration into its official stack.

The addition of WIZnet TOE support makes wired networking more efficient and accessible for the entire Zephyr user base.

About the Author (Contributor)

This pull request was submitted by Terry, a developer active within the Zephyr networking community.
Terry’s contribution demonstrates:

• deep understanding of Zephyr’s network subsystem
• practical knowledge of SPI-based Ethernet devices
• strong experience with offload networking architectures

Their work brings Zephyr closer to full TCP/IP hardware offload support for WIZnet chips.

Project Description — Moving From MACRAW to Full TOE

Zephyr’s current WIZnet driver only supports MACRAW mode, meaning the chip acts as a simple MAC/PHY interface while the MCU must run the full TCP/IP stack.

Terry’s pull request introduces:

✔ Full W5500 TOE (TCP/IP Offload Engine) support

The driver now leverages hardware-accelerated TCP/IP, handling:

• connection establishment
• retransmission
• timeout management
• socket handling
• packet segmentation and reassembly

This drastically reduces CPU load on resource-constrained MCUs.

✔ New socket-based API integration

The PR maps W5500 sockets to Zephyr’s unified BSD-like socket API, enabling standard networking calls (connect, send, recv, bind, listen) while the W5500 handles protocol complexity internally.

✔ Improved stability and performance

The author reports successful testing, including:

• long-running TCP communication with no MCU-side retransmission overhead
  
• stable throughput using only SPI bandwidth limits
• reduced CPU usage, especially when handling multiple concurrent sockets

These improvements highlight the benefits of shifting TCP/IP work into a dedicated hardware engine.

Why WIZnet Is Used in This Project

✔ True Hardware TCP/IP Offload

The biggest value of the W5500—and the core of this PR—is the TOE engine.
Instead of running lwIP or Zephyr Net stack on the MCU, the W5500 performs:

• TCP/UDP protocol handling
• State machine management
• Automatic retries and ACK management
• Packet segmentation
• Checksum calculations

This offload dramatically improves efficiency, especially on MCUs with limited RAM or flash.

✔ Simple SPI Control + High Reliability

The SPI interface simplifies board design while retaining robust Ethernet performance.

✔ Proven Long-Term Stability

WIZnet’s TOE chips are widely used in industrial systems requiring years of uptime.

✔ Ideal Match for Small MCUs

When developers want Ethernet without the cost of running a full software stack, WIZnet’s TOE devices are a perfect fit.

How This Contribution Benefits WIZnet

Even though WIZnet did not create this PR, it provides several meaningful advantages:

⭐ Positions WIZnet as a first-class Ethernet option in Zephyr

Native TOE support means WIZnet is no longer limited to MACRAW. Developers now see WIZnet as a complete networking solution, not just a MAC/PHY device.

⭐ Encourages adoption in commercial Zephyr-based products

As companies adopt Zephyr in production, having built-in WIZnet TOE support increases likelihood of W5500 design-wins.

⭐ Stronger community ecosystem around WIZnet hardware

Third-party driver contributions show that developers value WIZnet technology and want deeper integration.