--- title: "Implementing socket offload for W5500 in Zephyr" url: "https://maker.wiznet.io/viktor/projects/implementing-socket-offload-for-w5500/" markdown_url: "https://maker.wiznet.io/viktor/projects/implementing-socket-offload-for-w5500/md" type: "UCC: User Created Content" author: "TerryGeng" author_url: "https://github.com/zephyrproject-rtos/zephyr/pull/83413" editor: "WIZnet" editor_url: "https://maker.wiznet.io/" original_author: "TerryGeng" original_url: "https://github.com/zephyrproject-rtos/zephyr/pull/83413" published: "2025-12-11" language: "en" hardware: ["WIZnet W5500"] likes: 0 views: 539 comments: 0 source: "WIZnet Makers (https://maker.wiznet.io/)" --- # Implementing socket offload for W5500 in Zephyr > Implementing socket offload for W5500 in Zephyr Original author: TerryGeng (source: https://github.com/zephyrproject-rtos/zephyr/pull/83413) ## Components - **WIZnet W5500** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5500)) WIZnet parts: W5500 ([Datasheet](https://docs.wiznet.io/Product/Chip/Ethernet/W5500/datasheet?utm_source=maker&utm_medium=project&utm_campaign=w5500), [product hub](https://maker.wiznet.io/products/w5500/)) ## Article ## **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. [![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765463939%2Epng)](https://www.zephyrproject.org/wp-content/uploads/2025/06/Zephyr-Overview-20250626.pdf) 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 [![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765463960%2Epng)](https://www.zephyrproject.org/wp-content/uploads/2025/06/Zephyr-Overview-20250626.pdf) As Zephyr gains traction in commercial IoT, industrial connectivity, and wearable devices, hardware vendors benefit from integration into its official stack. [![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765463984%2Epng)](https://www.zephyrproject.org/wp-content/uploads/2025/06/Zephyr-Overview-20250626.pdf) 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. [![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765464013%2Epng)](https://www.zephyrproject.org/wp-content/uploads/2025/06/Zephyr-Overview-20250626.pdf) 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![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765463221%2Epng)** - **stable throughput using only SPI bandwidth limits** - **reduced CPU usage**, especially when handling multiple concurrent sockets ![](https://maker.wiznet.io/upload/ckeditor5/201746982%5F1765464095%2Epng) 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. --- Source: https://maker.wiznet.io/viktor/projects/implementing-socket-offload-for-w5500/