ESP32-S31 Arduino prebuilds practical?

[robertlipe]

TL;DR: Want some help on the ESP32-S31/Arduino 4 work?

Firstly, I fully understand what "not supported yet" means. I'm working no angle. I also know that things become supported because people are willing to invest in helping make it so.

I'm lucky to have an ESP32-S31-Korvo-1 V1.1. (You guys really need a Naming Person :-) )

Punchdrunk with the success of getting 'hello world' running from ESP-IDF master

ESP-ROM:esp32s31-20251218
Build:Dec 18 2025
[ ... ] 
I (247) main_task: Calling app_main()
Hello world!
This is esp32s31 chip with 2 CPU core(s), WiFi/BLE, 802.15.4 (Zigbee/Thread), silicon revision v0.0, 2MB external flash

Yay.

I was skimming the ESP32-S31 ESP-IDF status document and thought, "I can live with that.". The things that don't work are either things I don't care about today or are things that are (to my great annoyance) not supported by Korvo hardare. (A CP2102 on the USB-C jack in 2026? Seriously? "JTAG" is one of several four-letter words I have to say about that...) Looking at the state of the patch to add ESP32-S31 to Arduino I see it's likely to be in a simlar state, with most of the existing peripheral probably working or "just" needing to be hooked back up. I see it's actually a tad more complicated than that because it's stacked on top of the Arduino 4 branch.

I have three non-trivial projects I can entertain myself with for Korvo. The first two I haven't yet released, but are working OK on M5Stack Tab5 and various S3 or CYD targets. They're ESP-IDF but have substantial hardware components (External I2S on one, the horrible mess of everything all being on the same SPI bus on Tab5, so screen refresh, SD acccess, or even RAM/Flash internal accesses cause contention, so I have to kick the beautiful 360Mhz, dual-core, DMA-assisted race car into reverse every step, destroying performance) The second is my fork of NighDriverLED that's focusing on 'advanced hardware'. I may not quite be willing to chop mine up and add a HUB75 yet, but I can certainly find enought idle pins to dangle some WS2812 wigglies on a wire and confirm them with a scope or LA even if I don't DuPont in aoms 74HCT245s to driver real strips.

The NightDriver code currently builds in PlatformIO. (Hi, Jason!) I fought the long battle and am successfully running NightDriver with Arduino/3 via PioArduino I'm teetering on keeping FastLED3 (not 4) or moving to esp-ledstrip anyway.

I'll readily admit that Arduino gives me hives, but I also know it's strategic to some percentage of the marketbase.

If the S31/Korvo/Arduino4 arc is coming to a point of basically working and you want extra eyes and fingers on the code, I'm open to helping vet it on a real-world, medium scale (by S3 standards) c++ project or two and help validate it and debug or fill some empty checkboxes.

I have a systems/tooling background and can follow instructions for a Mac. I can work publicly or privately. Even if we "just" fix the warnings that we C++ devs have lived with from the system's headers, or help create/validate migration guides, it'll be worthwhile, IMO. [I've not fixed them so far because the project's primary builds are on PlatformIO/Arduino and, for a long list of (bad) reasons, that's GCC8 and IDF4, both of which are unsupported for some time.

The existing doc (that I can find) is oriented toward people developing with with arduino-esp32 instead of working on arduino-esp32 itself.

Are you at a point where extra hands would be helpful? ("No. Wait." is a perfectly reasonable answer, too. I have plenty of other projects...) If so, help me find/make a recipe to get this pile of bits building/running in Pioduino-like build. I don't care about the GUI part; I'll almost certainly script the meat of the build anyay.

If you don't want to contact me publicly here, my accountname is the same here as on GMail and the same domain for my blog (which has ESP32 stuff.)

Thanks for keeping microcontrollers interesting!

[me-no-dev]

You can give it a try if you install Arduino from git, using the idf-release/v6.1 branch. Instructions on how to install from git are in our docs. Make sure you remove core installed through ArduinoIDE's json before that. Keep in mind that this branch will be deleted and recreated from time to time. There is support for S31, but we are not yet sure what works and what doesn't. We know ADC does not yet work (pending updates in IDF), but whatever works in IDF should also work here. I've tested and updated ETH, but your board does not have one. We do not have Korvo boards yet and dev on Function EV boards. S31 will come to Arduino 4, because it's only supported on IDF6.1 and we try to follow Major IDF versions (Arduino 3 is on IDF 5). There will not be many things changed in terms of API, except BT/BLE and Zigbee (and maybe OpenThread). All other APIs should stay the same as in Arduino 3. Good luck and let us know!

[robertlipe]

Thank you. I welcome the encouragement.

I found instructions at https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#macos
...but those appear to be related to the Arduino IDE, which I definitely don't use. I'll need to know how to use it in platformio CLI builds.

I couldn't git branch --list and see the branch once cloned, so I modified the process to:

git clone -b idf-release/v6.1 https://github.com/espressif/arduino-esp32.git esp32 && \
cd esp32/tools && \
python get.py

The get.py finished and checked out the needed toolchains, but I don't see a top-level command for building and installing this.

 esp32  cmake .
CMake Warning (dev) in CMakeLists.txt:
  No project() command is present.  The top-level CMakeLists.txt file must
  contain a literal, direct call to the project() command.  Add a line of
  [ ... ] 
CMake Error in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 4.3)

I'm not sure if that's a dead end as there's not an obvious Makefile or CMakefile target, so I kept looking.

https://docs.espressif.com/projects/arduino-esp32/en/latest/lib_builder.html seems to be a lead. Note that I had to brew install coreutils gawk ninja with coreutils providing 'realpath' ... and it seems to duplicate the giti clones we were instructed to run in the other page.

It's not clear if it's using the set-target e31 that I specfied or if it's compiling the entire world for every ESP variation. Just looking at teh running cc1plus executions, it may be building the entire planet.

Is this the right path to pursue for a developer interested in making a custom build that lands in PlatformIO?

Since that ended in an error and I'm branches usually compile, I suspect I'm heading off into the weeds.

ents/arduino/libraries/USB/src/USBAudioCard.cpp:260:3: error: 'audio20_control_request_t' was not declared in this scope; did you mean 'video_control_request_t'?
  260 |   audio20_control_request_t const *request = (audio20_control_request_t const *)p_request;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~
      |   video_control_request_t
~/src/s31/arduino/esp32-arduino-lib-builder/components/arduino/libraries/USB/src/USBAudioCard.cpp:261:7: error: 'request' was not declared in this scope; did you mean 'p_request'?
  261 |   if (request->bEntityID == UAC2_ENTITY_CLOCK) {
      |       ^~~~~~~
      |       p_request
~/src/s31/arduino/esp32-arduino-lib-builder/components/arduino/libraries/USB/src/USBAudioCard.cpp:268:80: warning: missing initializer for member 'tud_audio_get_req_entity_cb(uint8_t, const tusb_control_request_t*)::<unnamed struct>::subrange' [-Wmissing-field-initializers]
  268 |         audio20_control_range_4_n_t(1) rangef = {.wNumSubRanges = tu_htole16(1)};
      |                                                                                ^
~/src/s31/arduino/esp32-arduino-lib-builder/components/arduino/libraries/USB/src/USBAudioCard.cpp: In function 'bool tud_audio_set_req_entity_cb(uint8_t, const tusb_control_request_t*, uint8_t*)':
~/src/s31/arduino/esp32-arduino-lib-builder/components/arduino/libraries/USB/src/USBAudioCard.cpp:357:3: error: 'audio20_control_request_t' was not declared in this scope; did you mean 'video_control_request_t'?
  357 |   audio20_control_request_t const *request = (audio20_control_request_t const *)p_request;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~
      |   video_control_request_t
~/src/s31/arduino/esp32-arduino-lib-builder/components/arduino/libraries/USB/src/USBAudioCard.cpp:358:7: error: 'request' was not declared in this scope; did you mean 'p_request'?
  358 |   if (request->bEntityID == UAC2_ENTITY_SPK_FEATURE_UNIT && request->bRequest == AUDIO20_CS_REQ_CUR) {
      |       ^~~~~~~
      |       p_request
[2075/2175] Building CXX object esp-idf/arduino/CMakeFiles/__idf_arduino.dir/libraries/SimpleBLE/src/SimpleBLE.cpp.obj
[2076/2175] Building CXX object esp-idf/arduino/CMakeFiles/__idf_arduino.dir/libraries/SD/src/sd_diskio.cpp.obj

I'm not a blockhead. I'm just asking for a boost of "follow these instructions to land a development build where it can be used by a CLI Platformio/Pioduino project with -efoo where foo sets esp32-s31 targets." What's the easiest way to get from this repo to that goal?

Onboarding doc is hard in every project. Those tools we all end up installing on our development machine become part of a project's culture before it makes it to the project's doc.

Thanks

[me-no-dev]

I don't know if you can build with PIO. @Jason2866 to the help

[Jason2866]

S31 support is not yet implemented in pioarduino. Since IDF 6.1 is used there are changes in a few pioarduino repos needed. Furthermore a PR here in the pioarduino-build.py script here too. I think i will have time to add experimental support in July.

[robertlipe]

OK, it's sounding like you're just not ready for help on this combo yet. I'll be back when the entry barrier is less harsh.

I was prepared to do things like tell the build it's an S3 or P4, capture the output, morph that into a script, tweak the include ordering and flags and such just to decouple python/packaging issues from actual toolchain issues.. I wasn't so much asking for it to be ready (that's the point/offer...) as much as for asking how to get to the starting line of sneaking a new IDF/Arduino4 build behind the skeleton of the build system. In fact, pitstopping a build with Arduino4 + S3 (probably P4 just for better tool flag compatibility even though the S3 peripheral pool is probably closer) before leveling up to S31 was a planned stepping stone. I get there are a lot of moving parts.

No problem. I have plenty of other ESP32 projects to keep me busy. It's just too early for S31/Arduino at this point. I have two IDF projects that would make reasonable test projects for S31/Korvo, though. They probably need to come forward from 5.5.4 to 6.01, then prep for 6.2 first anyway.

Thanx anyway.

(I'll leave this open for now in case there are other enthusiastic S31 users ready to try code bases that are stuck with Arduino.)