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.
Maybe Espressif will notice that there are no RV32 chips with MMU so far (at least to my knowledge); we only have 32 bit MCUs or then only 64 bits for the CPUs. Something like Cortex-A7 is missing.
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:
> You don't need long cables, just a local power source
Which means batteries that have to be replaced and maintained or cables... So ethernet with PoE or even better SPE (single pair Ethernet) with PoDL (power over data lines which is PoE for SPE) is the best from my point of view
I mean, if I just look at my house. There is just one ethernet outlet, but many power sockets. If I want to connect devices all over my house, the best way is to use wifi and usb power adapters. Not ethernet.
Both solutions require 1 cable per device, but the first solution would require only short and thin cables, and the second solution would require very long cables which I don't know even how to do properly without milling my walls.
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.
I wouldn't call it "better", but the least-effort path among hobbyists and low end gear is often 12v or 24v sent over a pair with Gnd and a forgiving voltage regulator on the other end.
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.
I assume their chips don't really exist until they're actually supported by ESP-IDF. The ESP32-C5 was announced in June 2022, received initial support in -IDF in August 2025, and more complete support in December. It seems to have only recently started getting third party dev boards.
It’s not like creating a chip gives you unfettered access to it. You _can_ add 0-day flaws and backdoors, but these can be discovered, leaked, etc. Has there been any case of such a backdoor built in consumer chips like theses? I’m not talking about CIA ops like snowden described, that’s supply chain interception. I mean, has anybody ever found such a backdoor?
Well, that depends on what you count as a backdoor, but Espressif has had some questionable flaws:
- Early (ESP8622) MCUs had weak security, implementation flaws, and a host of issues that meant an attacker could hijack and maintain control of devices via OTA updates.
- Their chosen way to implement these systems makes them more vulnerable. They explicitly reduce hardware footprint by moving functionality from hardware to software.
- More recently there was some controversy about hidden commands in the BT chain, which were claimed to be debug functionality. Even if you take them at their word, that speaks volumes about their practices and procedures.
That’s the main problem with these kinds of backdoors, you can never really prove they exist because there’s reasonable alternative explanations since bugs do happen.
What I can tell you is that every single company I’ve worked which took security seriously (medical implants, critical safety industry) not only banned their use on our designs, they banned the presence of ESP32 based devices on our networks.
Although, I'd like to seem some non-paid blogger head-to-head reviews benchmarking instruction cycle efficiency per power of comparable Arm vs. ESP32 Xtensa LX6* and RISC-V parts.
* Metric crap tons of WROOM parts are still available and ancient ESP8266 probably too.
That native sdk and the vscode plugin are very professional. There is a bit of a learning curve to get into it, but once you do, it's very functional and the developers are super supportive. They have fixed bugs for me in days.
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...
https://www.crowdsupply.com/silicognition/mant1s
Therefore, wifi is more convenient than ethernet.
You don't need long cables, just a local power source.
Which means batteries that have to be replaced and maintained or cables... So ethernet with PoE or even better SPE (single pair Ethernet) with PoDL (power over data lines which is PoE for SPE) is the best from my point of view
Both solutions require 1 cable per device, but the first solution would require only short and thin cables, and the second solution would require very long cables which I don't know even how to do properly without milling my walls.
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-...
I wonder if I at some point can create low power devices with EspHome for home assistant. I assume this should use less power than connecting to wifi?
https://esphome.io/components/zigbee/
It shocks me even more that any Western customer would do the same with network-connected Chinese chips. But we do.
The Espressif chips are truly incredible value, but what are we doing here?
Is there any doubt that these don't represent a major attack surface if a conflict were to heat up?
If you had network-connected chips of your own design inside every household of your adversary, what could you do with that?
- Early (ESP8622) MCUs had weak security, implementation flaws, and a host of issues that meant an attacker could hijack and maintain control of devices via OTA updates.
- Their chosen way to implement these systems makes them more vulnerable. They explicitly reduce hardware footprint by moving functionality from hardware to software.
- More recently there was some controversy about hidden commands in the BT chain, which were claimed to be debug functionality. Even if you take them at their word, that speaks volumes about their practices and procedures.
That’s the main problem with these kinds of backdoors, you can never really prove they exist because there’s reasonable alternative explanations since bugs do happen.
What I can tell you is that every single company I’ve worked which took security seriously (medical implants, critical safety industry) not only banned their use on our designs, they banned the presence of ESP32 based devices on our networks.
Although, I'd like to seem some non-paid blogger head-to-head reviews benchmarking instruction cycle efficiency per power of comparable Arm vs. ESP32 Xtensa LX6* and RISC-V parts.
* Metric crap tons of WROOM parts are still available and ancient ESP8266 probably too.
This is perhaps lost in the noise but IMO a large deal. PSRAM starting to get serious bandwidth.
I wonder if it will be possible to (ab)use the faster PSRAM interface on the ESP32-S31 as a general purpose 8-bit parallel interface, eg. for ADCs...
ESP-IDF, the official C SDK, is a bit more work, and there is drama around platform-io, but it’s significantly more stable.