Seeed Studio WT32-S1 Module for Ethernet to Serial

Seeed Studio WT32-ETH01

The WT21-S1 is an ESP-32-based embedded serial to Ethernet module. The module includes a full TCP/IP stack – etc etc – basically you can use it to program boards normally programmed serially – where that is not practical, by plugging this board into Ethernet via RJ45 and the relevant IO pins and power/ground into the target (ESP8266, Arduino etc).

I don’t have time to go into this in detail but I’m including links to the datasheet and the Seeed website.

If you have a use for such a device – it’s cheap! Don’t ask what all those connections are for – basically you would use ground, rx, tx and either 3v3 or 5v for many ESP8266 programming jobs. I tend to simply hold GPIO0 to ground manually on the target while programming (power-up with GPIO grounded, start programming, release) – but I believe that is catered for here. I’ll tell you more once I’ve waded through the docs.

Seeed have an application document if you are interested.


6 thoughts on “Seeed Studio WT32-S1 Module for Ethernet to Serial

  1. I just bought a WT32-ETH01 (not sure if this is the same as yours Pete). The one I have seems to be a fully-fledged ESP32 board, with an Ethernet interface added! I’ve been playing about with ESPHome and got it working with a Dallas temperature sensor and sending data via the Ethernet connection.
    Only 2 downsides so far…
    – First is that not so many GPIO’s are available as pins – I think quite a lot must be used internally for the ethernet.
    – Second, there is no USB/power connection. Power needs to be via the 5v or 3.3v pins, and the initial flashing needs a FTDI232 or similar. After that, OTA updates work over ethernet!

    Even with these limitations it still looks very useful, especially in areas of poor wifi. Much cheaper than the Olimex, WESP32, etc.

    1. Hello Raiko,
      I’m using ESPHome with mine, but several others are available. It’s available stand-alone and also as an add-on for Home Assistant – I’m using the HA addon, and it works pretty well. It stores code in .yaml format, and allows OTA updates for changes after the initial flashing, and generally makes running ESP32’s and ESP8266’s relatively painless. If you’re interested in learning more, has comprehensive information. Usual disclaimer, I’m just a satisfied user.

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