ESP32-S31: Dual-Core RISC-V SoC with Wi-Fi 6, Bluetooth 5.4, and Advanced HMI

https://www.espressif.com/en/news/ESP32_S31_Release

by topspin • 4 months ago

203 148 4 months ago

bestouff• 4 months ago

Is there something that match those elsewhere ?

hannesfur3• 4 months ago

Not across all features, but certainly in specific ones. There are more advanced WiFi 6 chips, more advanced Bluetooth chips and faster MCUs. But they are all separate chips or companion ICs.

moepstar2• 4 months ago

I believe this is the first ESP to gain Ethernet capability?

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…

3form• 4 months ago

This would be great indeed.

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?

jwr2• 4 months ago

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.

Etheryte• 4 months ago

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.

solarkraft• 4 months ago

I’m sure the other commenters are right, but I’m guessing market segmentation may play a role here too.

easygenes• 4 months ago

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.

[0] https://www.digikey.com/en/products/detail/silvertel/AG9705-...

throwup238• 4 months ago

Ethernet is already one of the most expensive standards because you need magnetics for isolation. Adding power on top of that is genuinely expensive.

Aurornis• 4 months ago

PoE power supplies need to be isolated (except in rare exceptions) and handle much higher voltages than common USB-C or wall wart power supplies.

They have to use a transformer and a more complex control strategy, not a simple buck regulator with an inductor. PoE inputs need to tolerate voltages several times higher than the highest USB-C voltages, so more expensive parts are used everywhere.

Geof25• 4 months ago

The original ESP32 has Ethernet as well, I believe in the form of RMII. Then it has been removed from the chip, never specified the reason.

elcritch3• 4 months ago

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:

- 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...

matt_trentini• 4 months ago

Waiting for my ManT1S:

https://www.crowdsupply.com/silicognition/mant1s

albuic3• 4 months ago

SPE with multidrop and PoDL would be awesome ! They are working on that and it will be everywhere.

toast0• 4 months ago

I'm more hopeful for single-pair ethernet to gain momentum though!

I keep looking for a reasonably priced 10baseT to 10Base-T1L bridge... everything commercial seems too expensive (for me) and the two hobby designs [1] [2] I've seen are not orderable :(

But I'm seeing more commercial options lately, so that's hopeful.

[1] http://robruark.com/projects/10BASE-T1L/10BASE-T1L.html

[2] https://matthewtran.dev/2024/08/10base-t1l-converter/

amelius4• 4 months ago

Because as it is right now, powering a fleet of those with USB power supplies is annoying as fsck…

Therefore, wifi is more convenient than ethernet.

You don't need long cables, just a local power source.

albuic3• 4 months ago

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

whynotmaybe2• 4 months ago

Esp32 's wifi is only 2.4ghz though.

exe34• 4 months ago

Can't you run a 5V supply from where your router is all the way to every god damn device in your house, and then pretend the wifi is also going through it? If you just want it to be inconvenient, there's no reason to let a lack of PoE stop you!

anigbrowl• 4 months ago

M5stack has PoE offerings

armx402• 4 months ago

No. It’s there already. I used Ethernet on esp32-p4 and it nicely hovers around 90-100 mbps with lan8720 chip.

logicallee• 4 months ago

Roughly how much do you think this costs?

ricardobeat4• 4 months ago

Given their history, I would guess <$6 a piece for a dev board, <$2 for the chip at scale.

Lwrless• 4 months ago

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.

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-...

maartin0• 4 months ago

It reminds me a bit of the new STM32s (STM32MP2) which are actually 64 bit, but they kept the name STM32 because everyone knows it

beng-nl• 4 months ago

Didn’t Intel also try to brand the 64bit x86 extensions as ia-32e initially? Seemed like wasting an opportunity to me.

(Disclaimer: I work at Intel but this was way before my tenure.)

madduci• 4 months ago

I stopped following the producer logic when Intel went from Pentium 4 to Pentium D

wosined• 4 months ago

The ESP32 boards I own have bad support and are a bit of a hit and miss. (arduino nano esp32) Did this get better? Or is the support still messy?

ricardobeat4• 4 months ago

Arduino nano are made by arduino using Espressif chips, and Arduino IDE support is indeed hit and miss.

ESP-IDF, the official C SDK, is a bit more work, and there is drama around platform-io, but it’s significantly more stable.

whynotmaybe2• 4 months ago

there is drama around platform-io

What do you mean ?

mianos• 4 months ago

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.

MallocVoidstar2• 4 months ago

Don't use the Arduino framework, use ESP-IDF or Rust.

PunchyHamster2• 4 months ago

how's Rust on the xtensa cores ?

usagisushi• 4 months ago

For those using PlatformIO, the folks at pioarduino[0] are doing a great job keeping up with Arduino Core 3.x support.

    ```
    # platformio.ini
    platform = https://github.com/pioarduino/platform-espressif32.git#55.03.37
    framework = arduino
    ```

[0]: https://github.com/pioarduino/platform-espressif32

cdcarter• 4 months ago

What do you mean by that? bad support for what?

Rochus2• 4 months ago

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.

volemo5• 4 months ago

That’s a shame, it’d be a cool and, afaik, unique feature for this niche.

Rochus2• 4 months ago

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.

IshKebab3• 4 months ago

Does anyone know what CPU this uses? Is it their own first party design?

ricardobeat4• 4 months ago

I hope this one has multiple radios so you can actually use BT/Wifi/Thread simultaneously.

volemo5• 4 months ago

How do Espressif’s RISC-V cores compare to existing ARM or RISC-V options in terms of power efficiency (computational power / electrical power)?

xondono2• 4 months ago

Don’t know the specifics of the Espressif RISC-V cores, but in general they can’t really compete on those aspects with ARM.

ARM is a much more mature platform, and the licensing scheme helps somewhat to keep really good physical implementations of the cores, since some advances get “distributed” through ARM itself.

Compute capabilities and power efficiency are very tied to physical implementations, which for the best part is happening behind closed doors.

6SixTy• 4 months ago

Without being hands on, it's difficult to make a direct comparison. There's 2 processors according to CNX [0], and the HP core's instruction set might roughly be comparable to M55.

[0] https://www.cnx-software.com/2026/03/24/esp32-s31-dual-core-...

urba_• 4 months ago

I don’t trust Espressif’s releases, I am still waiting for ESP32-P4 to hit distributors. It is now more than 2 years and 3rd chip revision

cbdevidal• 4 months ago

Can also be ordered on JLCPCB in a custom PCB: https://www.lcsc.com/product-detail/C22387510.html?s_z=n_ESP...

MallocVoidstar2• 4 months ago

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.

armx402• 4 months ago

I guess it hit mass production and then suddenly recalled and is now in sample status again with “X” variant. I designed boards using esp32-p4 and deployed and then suddenly local supply of esp32-p4 went dry. Now waiting for the x variant to go mass production but you can by samples directly from espressif for 3.33$.

peteforde7• 4 months ago

I have great news for you: after several years of growing frustration with Espressif's inability to launch this chip properly in NA, I found a company called Wireless Tag that presumably felt the same way and just did it themselves:

https://en.wireless-tag.com/product-item-56.html

I've now used this module in several projects. I love it. And I love (x3) the P4. It is amazingly powerful.

A lot of folks talk about the P4 not having radios as a problem; I personally think that it's an advantage. The assumption that every device is a wifi/BT device is baffling to me.

You'd have a very hard time convincing me to use anything but the WT0132P4-A1 at this point. They are cheaper than ESP32-S3-MINI-1U, too.

volemo5• 4 months ago

A lot of folks talk about the P4 not having radios as a problem; I personally think that it's an advantage.

I believe, the problem is that there isn't a comparable chip with WiFi/BT (ignoring S3, because, you know, Xtensa), not that P4 itself doesn't have them.

amelius4• 4 months ago

Does it run Linux?

la_oveja• 4 months ago

why would you do that? (unless for the fun of it)

amelius4• 4 months ago

Just to get an idea of its capabilities.

system2• 4 months ago

Imagine installing Claude Code in it with full root access. Just by asking a few things, you can have a semi-broken ESP32 doing stuff.

bavell• 4 months ago

No, missing a MMU.

mrighele• 4 months ago

There is μClinux [1] although it is not clear to me how much alive is the project

I wish I could run DiscoBSD/RetroBSD [2] on an ESP32, I like the idea of running on a MCU something that was originally meant for a PDP/11 (2.11 BSD)

[1] https://en.wikipedia.org/wiki/%CE%9CClinux

[2] https://github.com/chettrick/discobsd

madushan10002• 4 months ago

you can run linux on riscv without an MMU. There is mainline support for Kendryte K210 chip, so it should be possible port to this chip provided you have enough PSRAM.

MrBuddyCasino• 4 months ago

high-speed 250 MHz 8-bit DDR PSRAM with concurrent flash and PSRAM access

This is perhaps lost in the noise but IMO a large deal. PSRAM starting to get serious bandwidth.

1e1a• 4 months ago

For reference, the 4-bit PSRAM interface on the ESP32-S3 normally runs at 80 MHz (maximum 120 MHz) and shares bandwidth with the external flash.

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...

anymouse1234562• 4 months ago

Since the Snowden leaks in 2013, it just doesn't make sense that *any* foreign customers would put US technology inside their firewall. But they do.

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?

khalic2• 4 months ago

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?

xondono2• 4 months ago

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.

Mashimo• 4 months ago

Oh neat. Zigbee support.

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?

zrail• 4 months ago

You already can with nRF52 boards. Presumably they'll add ESP32 support soon too.

https://esphome.io/components/zigbee/

cataphract• 4 months ago

The C6 and the H2 already support ZigBee. Their SDK has a thin layer on top of zboss.

kunver• 4 months ago

Soon espressif will add TPU to their chips.

0x4573• 4 months ago

Hopefully it will be just added to https://github.com/espressif/esp-nn on software side.

burnt-resistor• 4 months ago

Interesting.

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.

ivanjermakov• 4 months ago

HN title entropy record?

phendrenad2• 4 months ago

Only a few characters away from my password!

bdavbdav• 4 months ago

Love ESP boards, and with Raspberry pi pricing though the roof, I’m hoping more will discover the love of getting the job done on a 10mm2 package.

I suspect a lot of the things people are using RPi for are better served by things like this (and virtualisation for the heavier end)

nirav72• 4 months ago

Argh…Wifi 6 , but 2.4ghz.

hajile• 4 months ago

Adding 2 frequency ranges is more expensive. If you're going to choose just one, you should choose the one with the greatest backward compatibility.

0x4573• 4 months ago

Realistically 2.4Ghz is far from "greatest backward compatibility" since there is a real benefit of running 5Ghz and 6Ghz only networks.

2.4Ghz makes sense because this tiny device does not need high speeds Wi-Fi connection, and deployment scenarios benefit from 2.4 GHz penetration more.

hannesfur3• 4 months ago

There is an ESP-C5 (https://www.espressif.com/en/products/socs/esp32-c5) that supports 2.4 and 5 GHz dual-band WiFi. And unlike the ESP32-S31 you can buy it today.

vlan08• 4 months ago

I don't understand what possesses these folks to continue making 2.4ghz devices. I understand there are use cases for low bandwidth, high range. But surely we've passed the point where that is more desirable to most than lower latency and high throughput, right?

joshryandavis• 4 months ago

I understand there are use cases for low bandwidth, high range.

Use cases like IoT? The very thing this is for?

vlan08• 4 months ago

Is what you described a truth for all IoT devices? If I have los of my AP, why do I need 2.4Ghz? Even so, what SNR do you truly need for this low bandwidth application? Where is the engineering here?

I have a unique position of having a data set over 8000 APs with 40k unique devices. If you design properly, there is no need for 2.4 ever. 2.4Ghz congestion (with nearly no actual 802.11 traffic) is very high. To the point where the IoT folks are struggling.

Havoc2• 4 months ago

My 2.4ghz is basically all IOT these days. Things that matter are on 5 or 6 ghz. Busy moving the entire thing to be entirely firewalled off given how clean the separation is

vlan08• 4 months ago

My 2.4ghz is basically all IOT these days.

Yup. And it's exactly why some of my IoT admins are struggling. There is only so much spectrum to go around.

mschuster91• 4 months ago

2.4 GHz has the advantage of it passing through obstacles easier. The higher the frequency the more easily it gets blocked.

vlan08• 4 months ago

Yes. And 2.4 lives and dies by that sword. What downsides might there be in areas where dozens of APs hear each other and 100s of clients hear each other?

leptons3• 4 months ago

It's an IoT device, not a laptop. It does not really need 5ghz to fulfill its purpose as an embedded CPU, and adding 5ghz likely would require making some room for it by removing other functionality.

vlan08• 4 months ago

Yes and in some uses cases it works against you. 2.4 is incredibly crowded without adding 802.11 to the mix. My IoT admins would have less complaints if they could take advantage of my small cell 5Ghz spectrum. This isn't 2005 with widely deployed asymmetrical wireless networks.

madushan10002• 4 months ago

Interesting that they made a new chip with BLE+BR/EDR again. all the chips after the original ESP32 were BLE only. Hope this chip has good low power options so we can use it in Bluetooth audio workloads.

zwirbl• 4 months ago

It supports LE Audio, might help getting that tech some traction

peterus• 4 months ago

It would be good if this chip had good idle current comparable to other MCUs. I have used the ESP32S3 and it's idle current with the radio enabled, but not transmitting, is quite terrible.

My application needed both can bus and Bluetooth (though no wifi) so the S3 was one of the only options available. I'm sure the high current draw is because the wifi and ble share the same radio?

Scene_Cast2• 4 months ago

I had the same theory, but IIRC the H2 isn't much better with radio on.

jxm2622• 4 months ago

Perfect timing. I just started planning to build a DIY smartwatch and was looking into the S3. Having native zigbee support could be nice.

alhirzel2• 4 months ago

The S3 (and other Espressif chips) are pretty power-hungry. May want to keep looking for a smartwatch application.

jxm2622• 4 months ago

S3 was just for me to do an initial prototype. Longer term was going to try with the C3, though I'm open to suggestions :)

sgraz• 4 months ago

Pardon for off topic. The designer in me hates that they used AI for every single asset in this release post, looks so amateurish.

elevation2• 4 months ago

Are there any US vendors with wifi/BLE-integrated MCUs -- a single package that does it all?

hannesfur3• 4 months ago

It has become limited. Some have WiFi, some have Bluetooth but rarely both. There is the SiWx917M (https://www.silabs.com/wireless/wi-fi/siwx917-wireless-socs) by SiliconLabs though.

If we include western companies you get the NXP RW612 (https://www.nxp.com/products/wireless-connectivity/wi-fi-plu...) which is dutch.

peteforde7• 4 months ago

Honestly, I have very little interest in this module. I was a frequent S3 user who switched to the P4 last year when I realized that I could buy it in a WROOM-sized package:

https://en.wireless-tag.com/product-item-56.html

The P4 is an amazing part, and the WT0132P4-A1 is cheap, highly available and easy to use. It has so much horsepower, and it's not encumbered by the mandatory wifi/BT stacks. It also has a genuinely superior capacitive touch solution compared to the S3.

For those of you who need radios, the recommended solution is to add a C3 as a coprocessor. I think this makes way more sense than bundling them, because it means you are free to use newer radio chips as they come out; this also makes the P4 somehow cheaper than the S3-MINI modules.

As for the S31, I just hope that they finally fixed the issues with ADC2.

ESP32-S31: Dual-Core RISC-V SoC with Wi-Fi 6, Bluetooth 5.4, and Advanced HMI

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