I'm puzzled by Espressif's naming here. We had the ESP32-S3, so "S31" sounds like "S3, variant 1," but this part doesn't really look like a simple S3 variant. And then there's an ESP32-E22, but no E21 or even a plain E2 anywhere.
It was because IA-64 was a completely different unrelated architecture that until AMD succeeded with K8 was "the plan" for both 64bit intel roadmap and the roadmap to kill off compatible vendors (AMD, VIA)
They claim that the chip has an "MMU". But unfortunately this doesn't seem to be a true RISC-V MMU (according to the Sv32 specification) integrated into the CPU core itself, but just a peripheral designed for memory mapped SPI flash and PSRAM. So as far as I understand there is no true process isolation with page faults and dynamic paging.
Nah, ESP32's have had ethernet capability for a while and ESP-IDF supports it well. I've been using one I built for 5+ years now. Unfortunately RMII (ethernet phy) interface takes up a lot of the GPIO pins. This part looks like it'll remedy that issue.
There's two ESP32 boards that have been around for a while with PoE:
On that note, why does the PoE capability often add such a big proportion of the price of various items? Is the technology really costly for some reason, or is it just more there's fairly low demand and people are still willing to pay?
PoE is not obvious to implement (take it from someone who has done it with a fair share of mistakes), uses more expensive components that normal ethernet, takes up more space on the board, makes passing emissions certification more complex, and is more prone to mistakes that ruin boards in the future, causing support/warranty issues. In other words, a bag of worms: not impossible to handle, but something you would rather avoid if possible.
A full-module add-on in this power class is about $7 at 1,000 unit scale [0]. It would be around $3 with your own custom PCB design in terms of BoM addon at scale. That’s power only. Add another dollar or two for 10/100 PHY.
The trick is as others have said in what adding it to your design does in terms of complicating compliance design.
Whenever you combine two things into one, the complexity and cost go up considerably. A regular coffee machine is pretty cheap. Add high pressure so it can make espresso and it gets considerably more expensive. Add milk so it can make cappuccino, again more complex and expensive. The same holds for electronics. Isolating power when it's alone is fairly straightforward. It gets considerably more tricky and hence more expensive the moment you want to place any kind of a meaningful data signal in its vicinity.
Edit: found an article explaining some of their naming logic, and said that the SoC naming will get its follow-up article, but sadly it never happened. https://developer.espressif.com/blog/2025/03/espressif-part-...
(Disclaimer: I work at Intel but this was way before my tenure.)
I totally wish that a board would come with PoE…
Because as it is right now, powering a fleet of those with USB power supplies is annoying as fsck…
There's two ESP32 boards that have been around for a while with PoE:
- https://www.tme.com/us/en-us/details/esp32-poe/development-k... - https://wesp32.com/
I'm more hopeful for single-pair ethernet to gain momentum though! Deterministic, faster than CANBUS, single pair, with power delivery:
https://www.hackster.io/rahulkhanna/sustainable-real-time-la...
On that note, why does the PoE capability often add such a big proportion of the price of various items? Is the technology really costly for some reason, or is it just more there's fairly low demand and people are still willing to pay?
The trick is as others have said in what adding it to your design does in terms of complicating compliance design.
[0] https://www.digikey.com/en/products/detail/silvertel/AG9705-...
ESP-IDF, the official C SDK, is a bit more work, and there is drama around platform-io, but it’s significantly more stable.