Tsvetan Usunov Turns the Olimex ESP32-POE Into a Low-Cost One-Wire Wi-Fi Gateway
Need a compact, low-power, low-cost way to connect Wi-Fi devices to a wired Ethernet network via NAT? Usunov has just the thing.
Tsvetan Usunov, founder of the Bulgarian open-hardware specialist Olimex, has showcased a new use for his Espressif ESP32-based Power-over-Ethernet (PoE)-ready microcontroller development board family: turning it into a low-cost single-wire Wi-Fi gateway.
"Need to share a wired internet connection over Wi-Fi, but want a compact solution powered through PoE," Usunov asks, rhetorically, by way of introduction to his latest project. "Here's an interesting open-source project that transforms an ESP32-POE or ESP32-POE-ISO into a Wi-Fi NAT [Network Address Translation] router using the Arduino IDE."
The Olimex ESP32-POE takes Espressif's classic ESP32-WROOM-32 module and put it into a gumstick-like format with a wired Fast Ethernet port at the far end. This isn't just for network connectivity: as the name suggests, it offers IEEE 802.3-compliant Power-over-Ethernet (PoE) support — meaning that, when paired with a compatible switch or a PoE injector, the board can receive its network connection and its power through a single cable.
While designed primarily with remote sensing and control projects in mind, Usunov has demonstrated the board's flexibility by turning into a low-cost Wi-Fi gateway — allowing any Wi-Fi-capable device to route traffic through the same wired Ethernet connection as the ESP32-POE itself. They're not connected to the network directly, though: the device acts as a gateway, rather than an access point, with its own isolated LAN and DHCP server, routing traffic through to the primary LAN and the internet using Network Address Translation.
Naturally, the Espressif ESP32-WROOM-32 is a little slower than the processor you'd find in a modern Wi-Fi gateway — despite being, with its two 32-bit Tensilica Xtensa LX7 cores running at up to 240MHz, a powerful microcontroller — which has a direct impact on throughput: Usunov has tested the connection at 4.8Mb/s.
More information is available on the Olimex blog, with source code available on GitHub under the reciprocal GNU General Public License 3; the code is compatible with either the ESP32-POE or the ESP32-POE-ISO, which adds galvanic isolation, both available on the Olimex store starting at €17.95 (around $21) before volume discounts and with hardware design files published on GitHub under the permissive Apache 2.0 license.