Unofficial guide to the WT32-ETH01
What is this thing and why would I use it?
The WT32-ETH01 is effectively a small, cheap ESP32 development board with Ethernet, WiFi, and GPIO pins, made by a company called "Wireless-Tag" (WT). As of this writing, it's around $15 at JacobsParts and around $7 from AliExpress.
There aren't a ton of ESP32 boards with Ethernet, and the WT32-ETH01 is by far the smallest, cheapest, and simplest. (The OLIMEX ESP32-POE and wESP32 are the other notable options.) So, if you want a cheap-and-cheerful ESP32 board with the reliability of a wired network, the WT32-ETH01 may be a good choice.
It's marketed as a "serial port to Ethernet module" and comes loaded with firmware that lets you send various "AT" commands over 3.3V serial to set up networking, open connections and exchange data. For most of us, it's more interesting to just flash our own programs on the unit and use standard ESP32 networking libraries.
Nobody knows much about the WT company. Don't expect support, and don't lock yourself in too much. Also see Luberth Dijkman's notes on the part.
Pins (and gotchas!)
EN ⏻ WT32-ETH01
(ESP32) ⭕ IO1 (reserved) 💬 TXD GND ⏚ ⭕ IO3 (reserved) 🗨️ RXD 3.3V ⚡ ⭕ IO0 (reserved) ⏱️ REFCLK and 💻 BOOT pull low to reset EN ⏻ ⏚ GND ADC1 CH4 📈 IO32 ↔️ ⬅️ IO39 (in only) 📈 ADC1 CH3 ADC1 CH5 📈 IO33 ↔️ ⬅️ IO36 (in only) 📈 ADC1 CH0 IO5 ↔️ ↔️ IO15 📉 ADC2 CH3 IO17 ↔️ ↔️ IO14 📉 ADC2 CH6 GND ⏚ ▶️ IO12 ⚠️ must float at boot 3.3V ⚡ ⬅️ IO35 (in only) 📈 ADC1 CH7 GND ⏚ ↔️ IO4 📉 ADC2 CH0 5V ⚡ ▶️ IO2 ⚠️ must float to program ethernet link light LINK 🖧 ⏚ GND
LEGEND
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