PicoChess v3.4 'Trixie' Images [24 Feb 2026]

[RandyR]

Hi Everyone,

For those who have yet to migrate to PicoChess V4 I have updated the v3.4 Trixie Desktop and Lite images to add Stockfish 18, Arasan 25.3, Texel 1.12 and updated to the latest version of MAME. There are also fixes to Rodent III and a few retro engine interfaces (no stock machines are affected by this).

Make sure you read the updated documents in the archive that you download especially if your Bluetooth eBoard isn't connecting. The Desktop image will likely have Bluetooth soft-blocked initially. The Lite image doesn't appear to have this issue.

The RPiOS Trixie files have not been updated (to save time). I carried out a full upgrade during testing (I answered 'YES' to the Chromium configuration file change) and found that Bluetooth became soft-blocked on both the Desktop image (again) and the Lite image. I executed the command mentioned in the Readme docs ('sudo rfkill unblock all') to fix it (your mileage may vary...).

I only carried out minimal testing so let me know if you run into issues. Also, with PicoChess V4 now stable and incorporating exciting new features, this will likely be the last v3.4 image update.


Enjoy,

Randy

The links remain the same:

64-bit v3.4 Trixie Lite (5.1 GB)

64-bit v3.4 Trixie Desktop (7.0 GB)

[Johan Sjöblom]

Nice work.

Could I basically take the lite image files and update all the relevant aarch64 resource files in V4 with exactly the same engines folder content? I could add the fairy stockfish engine for variants.

—Johan

[Randy Reade]

You will have to pick and choose the files as the folder structure is different in V4 compared to my images. You can look at the modification dates to know which files have changed. But you'd have to compare with the previous v3.4 Desktop or Lite images to see exactly what changed (some deletions and renames (e.g. c-patricia vice c-arasan)). 

I'm currently working on creating v4 images but have run into sound issues as soon as kiosk was installed (scratchy/broken at startup. I think it has something to do with chromium but am not sure. If I disable kiosk, the sound goes back to normal. Anyway, my plan was to update the engine files on there and create an updated resource file. Or, I could just download the resource file(s) and make the changes 'offline' rather than trying to sort out the sound issue.

Randy

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[Johan Sjöblom]

Ah, ok. Its not that easy then. If you do manage to make new V4 image that would be really great (obviously). 

I could then update the resource files based on that image so that an install on a standard Pi image would produce the same result.

If I open a new release tag any collaborator could update a resource file… I think.

— Johan

 PS. I have switched my day job to a new one so for a while I will have limited time to fix things.

[Randy Reade]

Check your mail. 😊

To view this discussion visit https://groups.google.com/d/msgid/picochess/5e434b58-7846-46ba-aa52-99149a5c481bn%40googlegroups.com.

[Johan Sjöblom]

Thanks Randy. Any new install (or engine upgrade) of V4 now installs these new files.

542229532 Feb 25 20:36 engines-aarch64-lite.tar.gz
166936449 Feb 25 20:29 engines-aarch64-small.tar.gz
535907465 Feb 25 20:34 engines-mame-lite.tar.gz

I could not download the rodent3 file yet... will fix that one tomorrow.

[RandyR]

Sent you an email.

I think the sound issue is due to 3 instances of a-stockf running at 100% (htop) while PicoChess is running, leaving just one processor for everything else on the Pi (including PicoChess. And they stay at 100%:

[DJ Dekker]

Hi Randy,

When building the images, please remember that Arasan 25.3 requires the network file arasanv5-20251222.nnue to be present in the same folder as the engine. Without this file in place Arasan 25.3 may crash after leaving the opening book. So this network file must be included in the engine pack and the image files.

The file is getting written while compiling Arasan. It is also available for download from my Google drive.

Greetings,

DJ

Op woensdag 25 februari 2026 om 20:11:31 UTC+1 schreef RandyR:

[Randy Reade]

Hi DJ, 

You can also specify the network file in arasan.rc or via the .uci file (which is what I did).

Randy

[RandyR]

Ok. I see what's happening. Default install of v4 has a-stockf as the selected engine in picochess.ini but there is no engine-level specified so it defaults on the highest level which uses 3 threads. I think we should use a lower level in the picochess.ini examples, especially for the DGTPi which doesn't have active cooling out of the box.

[Gaspar Marqués]

No encuentro la imagen de la version lite de picochess V4 para DGTpi, si alguien pudiera mandarme el enlace, gracias.

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[DJ Dekker]

Hi Randy,

In the case of Arasan setting the parameters in the .uci file is the preferred approach now. Starting with version 25 Arasan does not read the arasan.rc file anymore, unless specifically instructed to do so. So we might even get rid of arasan.rc altogether(?).

Greetings,

DJ

[Randy Reade]

Ah, good point. Yes, we may as well remove it as it would require either hard-coding Arasan to read it or needing a batch file to supply the -a option (if that would even work in PicoChess). I'll remove it on the next engine (or image) update.

Randy

[Johan Sjöblom]

Randy, I updated all the example ini files to have an uncommented:

engine-level = Elo@2200

That level is high enough for most players, but it still does not have any threads setting so the default threads = 1 is used.

[Randy Reade]

That should be better. I think it was also the cause of the sound issues I was trying to solve last week, fingers crossed...

One other thing that needs fixing is the kiosk script to set ownership of ~/.config/autostart to, e.g., pi:pi when the folder did not previously exist. Currently it is set to root:root.

[Johan Sjöblom]

Right! You did mention that earlier but I did not see the problem then. Now I fixed the install-kiosk.sh to make sure both dirs ~/.config and ~/.config/autostart are owned by the install user (typically pi).
I also fixed the rodent3 resource file that for some reason I failed to download yesterday evening.

[Randy Reade]

Great! I'm working on the v4 image creation, trying to see if I can use cloud-init on a custom image to set up WiFi after flashing the micro SD card but before booting (like was possible with wpa_supplicant.conf). If I can't get it to work WiFi will have to be set up after boot, as is the case now.

[DJ Dekker]

Could the three threads also be explained by PicoTutor being active? In picotutor.py two instances of a-stockf are being initialized if the tutor is watching. If the user is also playing against a-stockf at a non-maximum level, that would explain the third instance.

Op woensdag 25 februari 2026 om 21:49:23 UTC+1 schreef RandyR:

[Randy Reade]

Yes. That can happen but in this case PicoTutor wasn't enabled. And the game wasn't started. Johan explained in an older post why the engine is always initialized and running. I think it was for analysis. Maybe Johan can explain it again or point to the post. Also, I mentioned the DGTPi being at risk but thinking later I believe the Pi would just go into throttling if it got too warm.

Randy 

[Oswaldo Monteiro]

Hello all

pls,  The real question is whether the Elite AvantGarde engine is actually the true 'MessChess.' In a 15-minute game, I spent very little time per move and still managed to develop my pieces with ease, gaining a massive advantage. Is this truly the authentic engine?

[Event "PicoChess game"]
[[Date "2026.02.26"]
[White "Player"]
[Black "Fidelity Elite Avant Garde (pos+info) (3-60/15m) (100%)"]
[Result "1-0"]
[ECO "D12"]
[WhiteElo "1500"]
[BlackElo "1835"]
[WhiteFideId "-1"]
[BlackFideId "-1"]
[PlyCount "60"]

1. d4 d5 2. c4 c6 3. e3 Bf5 4. Nc3 e6 5. Nf3 Nf6 6. Be2 Bb4 7. Bd2 O-O 8. O-O {Threatening Nxd5!.} dxc4 {The position is equal.} 9. Bxc4 b5 10. Be2 Bd6 11. Rc1 Nbd7 12. a3 a5 13. Nh4 Be4 14. Nf3 Bg6 15. Nh4 Qb6 16. Nxg6 hxg6 17. Bf3 g5 18. Qc2 g4 19. Be2 Qb8 20. g3 Qb6 21. Ne4 Nxe4 22. Qxe4 c5 23. dxc5 {White is more active.} ({Don't do} 23. Bxg4 $6 Nf6 24. Qc2 (24. Qf3 cxd4 25. Rc6 {Deflection} Qd8 $16) 24... Nxg4 $11) 23... Nxc5 24. Qxg4 Nb3 $2 {This costs Black the game.} (24... f5 $16 25. Qd4 Rfd8) 25. Bc3 $18 {[#]} e5 26. Rc2 {and Rd1 should not be overlooked} b4 27. axb4 axb4 28. Be1 Na5 29. Bf3 Rad8 30. Be4 b3 $2 {Weighted Error Value: White=0.20 (precise) /Black=0.32  Mistake:       ---       Black=2      Inaccurate:     White=6     Black=7      OK:         White=10     Black=9      Best:         White=3     Black=1} (30... Be7 31. Qh5 g6 32. Qxe5 Rfe8) 1-0

Oswald

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