Wiznet makers

📌 A W5500 Gives the OpenIndus OI-Core Its Wired Ethernet Port

OpenIndus is an engineering company founded in February 2017 in Toulouse, France, that designs and sells a modular industrial controller family under the tagline "Robotique, électronique et automatismes industriels" (robotics, electronics and industrial automation). The OI-Core is the head of that family, and the vendor's own firmware documentation states where its network port comes from: "Ethernet functionality is available on the OI-Core module, featuring an embedded Wiznet W5500 chip."

The OI-Core is a rail-mounted control unit built around an ESP32-S3, a dual-core LX7 processor at 240 MHz with 8 MB of flash. Because the ESP32-S3 has no Ethernet MAC of its own, the 10BaseT/100BaseTX port on the OI-Core exists only because a W5500 sits between the RJ45 jack and the processor's SPI bus. The product was listed in stock at 226.00 EUR excluding VAT on the OpenIndus boutique when this article was checked on 28 August 2026.

The back of an OI-Core unit. The label carries three MAC addresses, one each for Wi-Fi, Bluetooth and the W5500 Ethernet port. Photo: OpenIndus product page.

That label is a compact summary of the module's network design. Each unit ships with MAC addresses printed for WIFI, BLTH and ETHE, so a single OI-Core can sit on a wired plant network through the W5500 while still exposing Wi-Fi 802.11 b/g/n and Bluetooth 5 through an external SMA antenna connector.

Vendor, Availability, and Price

OpenIndus SAS is registered in Toulouse (RCS Toulouse 827 786 955) and sells directly from its own web boutique, with no distributor named on the site. The company describes itself as both a product maker and a "bureau d'études", an engineering office that also delivers custom control systems. Its GitHub account publishes five repositories: the oi-firmware sources, a VS Code extension, mechanical drawings in STEP format, and two demo-kit projects.

Purchasing is direct rather than quote-based. On 28 August 2026 the boutique listed the variant named "OI-Core no 4g" at 226.00 EUR excluding VAT and marked "En stock", the Ethernet-less OI-CoreLite at 189.00 EUR, and a third listing named "OI-Core Just eth" at 379.00 EUR. The store's variant names do not spell out which options the 379 EUR listing bundles, so the 226 EUR entry is the verifiable price for an Ethernet-equipped OI-Core. The OI-Core product page advertises shipping within 48 working hours, a 2-year manufacturer warranty and included technical support.

The OI-Core product page itself never names the chip. Its description says "Ethernet 10BaseT/100BaseTX (OI-Core uniquement)" while its short specification block says "Ethernet 10 Mb/s", and the W5500 is identified only in the firmware documentation, which is why this article cites the product page and the documentation together.

One Master Module Drives a Rail of Slave Modules

The OpenIndus system is a modular PLC: a powered communication rail holds up to 9 units of modules, rails chain together over USB-C cables, and one master module commands every slave module. The product page puts the master role plainly: "L'OI-Core est le microcontrôleur industriel maître de l'écosystème OpenIndus", the master industrial microcontroller of the OpenIndus ecosystem. A developer writes one program for the OI-Core and never flashes the I/O or motor modules individually.

The vendor's I/O demonstration panel, with two labeled modules on the communication rail. Photo: OpenIndus boutique.

The boutique catalog on 28 August 2026 shows how the family divides the work, with all prices excluding VAT:

Within that catalog, the W5500 marks the network tier. Wireless control is available on every master, but a machine that must join a wired factory network gets there only through the OI-Core.

⚙️ Role of the WIZnet W5500 in the OI-Core

The firmware documentation dedicates a page to the Ethernet function, and it reads like a W5500 datasheet extract: hardwired TCP, UDP, ICMP, IPv4, ARP, IGMP and PPPoE support, 8 independent sockets, Wake on LAN over UDP, and an embedded 10/100 PHY with auto-negotiation. The same page carries a wiring caveat straight from the board design: "user should use straight-through cables to connect to other switches or routers and crossover cables to connect to devices such as servers, workstations or another W5500", because the OI-Core implementation does not enable auto-MDIX.

The Ethernet page of the vendor documentation, captured on 28 August 2026. Screenshot: openindus.com/oi-content/doc/latest.

The published example, docs/examples/Ethernet.cpp, shows the exact hookup. It defines ETH_PHY_TYPE as ETH_PHY_W5500 with chip select on GPIO18, and starts SPI on SCK GPIO17, MISO GPIO16 and MOSI GPIO15 before calling ETH.begin(). The code path runs through the arduino-esp32 ETH class, which attaches the W5500 with ESP-IDF's esp_eth driver, so TCP and UDP are handled by lwIP on the ESP32-S3 while the W5500 serves as the wired MAC and PHY. The example then fetches a web page over a NetworkClient to prove the link.

Generated technical diagram, built for this article from the oi-firmware documentation and boutique descriptions.

Around the network path, the OI-Core keeps a full industrial interface set: CAN from 50 kbps to 1 Mbps, half-duplex RS232/RS485, 5 V tolerant I2C, four digital inputs, four digital outputs, two 0-30 V analog inputs, a 5 V/500 mA sensor supply output, a microSD slot and a battery-backed RTC. The module accepts 9 to 30 V DC, is rated from -20 to +70 degrees Celsius, and draws under 1 W with outputs disabled.

Where the OI-Core Splits from the OI-CoreLite

OpenIndus sells the same control brain in two packages, and the wired port defines the split. The OI-CoreLite in the small BOI13 housing keeps Wi-Fi, Bluetooth and the field buses; the OI-Core in the larger BOI23 housing adds the W5500 Ethernet port, a USB Host 2.0 connector, a PoE supply option and an optional 4G LTE-M modem with 2G fallback. The documentation confirms the two share one pinout, so a design can move between tiers without rewiring the terminal blocks.

Generated technical diagram. Variant names and prices are quoted from the OpenIndus boutique as read on 28 August 2026.

Programming Path and Firmware Activity

OpenIndus documents a single development flow for the whole family: install Visual Studio Code, add the OpenIndus extension from the marketplace, and let it pull the ESP-IDF toolchain. The firmware exposes an Arduino-compatible API on top of ESP-IDF v5.5, so the Ethernet example above is a standard sketch with setup() and loop(), flashed over the module's USB micro-B port.

The repository shows steady maintenance rather than a static archive. It was created on 11 October 2021, the v2.0.0 migration to ESP-IDF 5.5 landed on 19 September 2025 in the same commit that last touched the Ethernet documentation, version.txt reads v2.1.1, and the last push recorded by the GitHub API was 11 June 2026. The repo had 5 stars and no open issues on 28 August 2026, consistent with a vendor-run distribution channel rather than a community project.

Where OpenIndus Hardware Runs

The vendor's project page documents two deployments of the rail system. With Igus, the German motion-plastics manufacturer, OpenIndus built the control system for a 3-axis gantry laser-engraving demonstrator, using one OI-CoreLite and two OI-Stepper modules configured through a web interface; OpenIndus states that Igus now treats it as a referent integrator for its robots in southern France. With the I2M laboratory of the University of Bordeaux, OpenIndus develops control systems for a delta robot doing WAAM metal additive manufacturing, where the controller loads G-code files through a web interface.

The Igus demonstrator ran on the CoreLite master, and the OI-Core with the W5500 addresses the installations both cases point toward: a machine cabinet where the controller must publish its state or accept jobs over the plant's wired network rather than over Wi-Fi.

What the Public Sources Show and What They Do Not

The W5500 claim rests on the vendor's own firmware documentation and example code, both public on GitHub since the repository opened in 2021, and the docs are republished on openindus.com. No board schematic is public, so the chip cannot be verified from a layout file, and no photo of the bare PCB has been published. The product photos are studio cutouts, but they show unit-specific serial numbers, MAC labels and QC stickers of real production hardware.

The firmware repository carries no open-source license file, and its source headers mark the code as OpenIndus copyright, all rights reserved, so the public code is reference material rather than a reusable library. No independent review or field report of the OI-Core was found during research for this article on 28 August 2026, which matches a product sold directly to industrial customers rather than through hobbyist channels.

Related WIZnet Maker Projects

Monolitix: A compact PLC you program in VS Code shares the same recipe, a commercial PLC with a WIZnet Ethernet port programmed from VS Code, but Monolitix is a single compact unit while the OI-Core is the master of an expandable rail of I/O and motor modules.

Why Does the boneIO gen 2 DIN-Rail Dimmer Use a W5500 Instead of LAN8720? documents the same silicon logic from Poland: an ESP32-S3 has no Ethernet MAC, so a vendor that upgrades to it keeps the wired port by adding a W5500 on SPI. boneIO serves smart homes, OpenIndus serves machine builders.

OpenKNX REG1: A Bus-Powered DIN-Rail KNX-IP Router on RP2040 and W5500 is another European rail-mounted device where a W5500 provides the IP side, but it bridges a KNX building bus on an RP2040, while the OI-Core commands its own proprietary module rail from an ESP32-S3.

❓ FAQ

Q. Which WIZnet chip provides Ethernet on the OpenIndus OI-Core, and where is that documented? The W5500. The firmware documentation at openindus.com/oi-content/doc/latest and in the oi-firmware GitHub repository states the module features "an embedded Wiznet W5500 chip"; the store page lists only the Ethernet port without naming the chip.

Q. How is the W5500 wired to the ESP32-S3 inside the OI-Core? Over SPI, per the vendor's Ethernet.cpp example: SCK on GPIO17, MISO on GPIO16, MOSI on GPIO15 and chip select on GPIO18. The example attaches the chip through the arduino-esp32 ETH class using ESP-IDF's esp_eth driver.

Q. What is the difference between the OI-Core and the OI-CoreLite? The OI-Core adds the W5500 Ethernet port, a USB Host 2.0 connector, a PoE supply option and an optional 4G LTE-M modem to the CoreLite feature set, in a larger BOI23 package with the same pinout. On 28 August 2026 the boutique price gap was 226.00 versus 189.00 EUR excluding VAT.

Q. How much does the OI-Core cost and can it be bought now? The "OI-Core no 4g" variant was 226.00 EUR excluding VAT and marked in stock on the OpenIndus boutique on 28 August 2026, sold directly by the manufacturer with 48-hour shipping and a 2-year warranty. A 379.00 EUR listing named "OI-Core Just eth" also exists, with the option mix not spelled out on the store.

Q. Can the whole OpenIndus rail system be programmed through the one OI-Core? Yes. The OI-Core is the master of the rail: one program on it commands the OI-Discrete, OI-Mixed, OI-Stepper, OI-RelayHP, OI-AnalogLS and OI-DC slave modules, so the slaves need no individual firmware work.