Holy Grail Of MCU's


I was thinking the other night how great it would be to have an MCU that had these capabilities:

  • Compact
  • Affordable
  • Ethernet connectivity
  • Passive/Active POE
  • 4MB+ Flash
  • 48 MHZ+ clockspeed
  • Optional Wifi (not really a need with Eth)
  • 10+ useable GPIO pins

If you think about it, 95% of the devices you have required a DC current and most of the time within the house that’s supplied from an ACDC adapter, that requires a wall socket. Why not just use PoE with 5-6v and a splitter?

I have seen a few ESP32 units offering as such, but at a considerable price, and to be honest, the ESP32 is a beast and is really overkill for most basic home automation tasks.
An IC like an ESP8266 / ESP8285 or the SAMD21 would be great for most things I would think.

I have been contemplating building my own module with an ESP-12, line driver and magnetics chip, and just splitting the PoE out or look at an active circuit.
Currently, I am just building a basic system with a PoE splitter to ethernet module SPI connection to an ESP8266. It’s bulky and if it was all on the one PCB it would be 2-3x more compact.

Have any of you found anything like this (with the “affordable” in mind lol)? or is it even worth putting the time into designing something like this?


The wesp32 looks promising if the price comes down a bit, I didn’t realise that the ESP32’s have dropped a fair bit in price anyway, with the additional GPIO’s and for only 10AUD its a pretty good option now. especially if you factor in how many GPIO’s are required when connection to Ethernet.

if they can get the wesp32 down to $20-25 it could make a perfect option. I also noticed to can get ESP32 dev boards with Eth on for less that 15AUD, they are just rather large.

I guess the advantage of using the ESP32 is i think it has default Eth MAC addressing, most other ESP’s I dont think have this by default.


The Olimex ESP32-POE is available for around $20 USD which I think is around $30AUD (CAD and AUD are usually pretty close) The only real problem with it that the wesp32 fixes is that you can’t use the USB port and POE simultaneously. No power isolation. So when programming over USB you have to use an unpowered ethernet port.


@DavidRK The ESP 32’s are getting even cheaper. I picked up 10 Devkit V!'s for $46 US from Ali Express 2 weeks ago, including shipping. You can get the Wroom chips themselves for a buck something a piece so the cost is coming down. I was looking at that for my package vaults and just because the devkit boards are so inexpensive, I went with the full board. I can header it onto an add on board to do anything additional. But yes… overkill for most things home automation.


Got me some ESP32s on the way, I have a few Eth modules hanging around so I will try making up some ad-hoc PoE controllers.

@polargeek I have ordered one of the Olimex to see how they fair and possibly in a few weeks I’ll order a wesp32 on their next round, compare the 3 for price/performance/ease.

The main goal is for a room monitoring system I have on the cards, it will comprise a range of sensors for each room in the house to give telemetry (light, temp/humid, activity, air quality).


The WESP32 is nice but at $73/ea it is a bit above my budget. The ESP32-POE-ISO from Olimex is a much better deal. It is the upgraded version of the ESP32-POE with isolation. It’s a bit more expensive but nothing like the WESP32. Personally, I am exploring using the Orange Pi One. Delivered they cost $13 and they have onboard Ethernet and Raspberry Pi compatible header. I also just found out that the orange pi zero, the baby brother to the One, has POE. I’ll want to check that out more thoroughly. They also have several sensor packs, if you are looking to make a sensor array of some kind, The sensor packs are a great deal and come in different flavors (sound, weather, etc) or all of them for $27. You can find all of the Orange pi boards at Aliexpress https://www.aliexpress.com/store/all-wholesale-products/1553371.html?spm=2114.12010612.0.0.5d69395cI5oeW4


The Orange Pi stuff is interesting but those are more SBC like Raspi’s or Tinkerboards than they are MCU’s like ESP’s and Atmega’s correct?


@MisterFixit1952 Did a little research on that POE option. It’s not real POE. There’s pads you can bridge if you send 5v passive POE. If you wanted to do higher voltage you’d have to wire a buck convertor inline and I’m not even totally clear on how you would wire in an IEEE 802.3af regulator if you wanted to do proper negotiated POE voltage you’d be better off using the same active POE splitters I use for my raspberry pi’s


Think I will put my room hub idea on hold for a few months until I can make my mind up with what path I go with, I will at least test the wesp32, Olimex and my own passive modular approach to get the firmware sorted and get a feel for the hardware.

Hopefully, prices come down a bit by then.