mGBA Forums - Development

New Solar Sensor Device

Tue, 20 Jan 2026 18:47:58 +0000

I'm currently working on an ESP32-based device for reading actual UV levels (not just artificial light) for playing the Boktai games as originally intended. I'm focusing on making it very easy and cheap to build. It will be open source.

The easiest way to make it work with any version of mGBA (PC, libretro core, etc,) would be to enter the exact solar value via the controller hotkeys. The problem is, only increments and decrements are currently supported. The device and mGBA could easily lose sync.

I'd like to add inputing exact solar meter values in a way similar to this...
0 bars: L3
1 bar: Up on left analog + Up on right analong + L3
2 bars: Up on left analog + Right on right analog + L3
... and so on. I could figure out the best combos later, but they should all be analog-based.

What's the best way to do this? Code it for the main branch and the libretro branch then issue PRs? Thanks!

2.5x integer scaling of GBA scaling to VGA screens

Sun, 16 Feb 2025 13:42:39 +0000

Hi All,

Love mGBA, but I hate how 640x480 retro handhelds make GBA games look. It's either uneven or blurry, or both.

With millions of people playing GBA games on such devices and screens, I think we could do a better job.

I used to be an embedded game dev for over a decade, so I came up with a simple but elegant scaling algorithm, that is consistent and retains the sharpness without uneven text.

I'd love to integrate it to mGBA, if possible. It'd be a very specific scaler for the 240x160 to 600x400 scaling only, although I could generalize it to be useful for 2.5x, 3.5x, 4.5x scaling the same way.
Would this be okay to implement here? If so, where in the architecture would it fit best @endrift?

Here's a simple .js implementation and some samples:
https://stupendous-kelpie-bea103.netlify...20(3).html

Cheers,
Peter

Screenshot 2025-02-16 at 14.42.13.png (Size: 186.62 KB / Downloads: 1)

ps vita analogue mapping

Mon, 01 Apr 2024 11:58:12 +0000

Hi, thanks for this awesome job, question though. Is there any quick option for me to alter something to have this respond to both Analogue sticks for the directions. I can then play 1 handed on either side of the vita. I have seen in the config files to possibly switch from 1 to the other.

Real GBA to Emulator link

Wed, 27 Mar 2024 04:59:40 +0000

Wondering if anyone has tried to take the GBA link cable and connect it to a PC usb port, then take the packets sent from GBA--->into emulator-->multiplayer, and vice versa?

Was going to try for "random" software coding practice.
Where do I find source code??>>

If someone has tried this, where can I find documentation?
Ultimate goal is to make a tiny link cable board that connects to wifi and uses emulators as host software for multiplayer.
Something like the wireless link, but modern.

Also will mGBA run on a Pi board version of linux? was gonna use a tiny pi thats like half the size of a zero W.

Accessing GB ROM Banks from Lua

Thu, 23 Nov 2023 21:08:03 +0000

I'm writing a script meant to run with arbitrary games that can read data and send it over a socket. It doesn't look like there's a way to directly read ROM data for GB games. Only `memory.cart0`. So if the script is asked to return data in bank 4 or whatever it may not be addressable and the data is unknowable. Any chance I'm missing some obscure way to get at the ROM? I'm much less familiar with GB/GBC than GBA, so let me know if I'm mistaken about something.

I'm coming from the context of BizHawk which uses Gambatte and does allow access to the entire ROM from lua under the domain they label "ROM".

C++ Wrapper for Scripting API

Sun, 13 Aug 2023 01:20:03 +0000

Hi,

I don't know if this is the proper place to open this thread but I don't have access to any other dev related sections.

I programmed a little Wrapper for the Scripting API, which is written in C++ and could easily be ported to other languages like e.g. python.

With this Wrapper you can execute functions like e.g. reading or writing to memory, retrieve game code or title and sending key presses.

The wrapper works by setting up a TCP server on the C++ application and a TCP client with a LUA file on the emulator. Afterwards commands are sent from the server to the client and parsed in LUA and results are sent back.

I did it because it was a cool experiment for myself and also because I wanted to do external cheat's for some GBA games.
Also I chose to not read/write directly into the emulators process memory, so it could support more version's of mGBA (dependend of the script api and not e.g. byte signatures etc.)

This was pretty fun to me and I hope this could also be somewhat useful to you guys.
Everything is open-source and for you to access right away.
Also I'm quite busy but if I find any time to work on this in the future, I'll be more than happy to extend the current feature set and make it more stable.
Please be aware that this project was coded in 3-4 hours and I never messed with mGBA nor Lua before that.

https://github.com/cragson/mgba-api

Also I did already a small cheat for Pokemon Mystery Dungeon Red Rescue Team, which can be found here:
https://github.com/cragson/pkm-md-red

I'm always open for any kind of constructive feedback!
Regards,
cragson

Feature Request: Compatibility with the Advance Game Port

Mon, 03 Jul 2023 13:45:44 +0000

There was this third party accessory for the Gamecube, called the Advance Game Port. It consisted of a dongle that plugs into a Memory Card slot on one end, & a slot to play GBA cartridges on the other. The other part was a disc, which could read what was on the Port, and ran a quite subpar emulator.
On the Gamecube, it's obsolete in the face of the Game Boy Player, but on the Wii, it's the only way to play GBA games off the cartridge.
I was wondering if maybe we could find some way to get the Wii version on mGBA to read what was on the Port, and play GBA games on an emulator that works much better than Datel's offerings.

A link explaining the Port in more detail + pictures
https://www.nesworld.com/gcn-advancegameport.php

I know nothing about coding with Wii homebrew, but I will accept any way I can help!

Sample lua scripts or code snippets

Sun, 25 Jun 2023 16:58:23 +0000

I'm glad to see that mGBA is now supporting lua scripting. Are there any sample code snippets available?

Specifically, I'm looking for guidance with the TCP socket APIs. I have a server created in an external program, but I can't get the lua script to connect and send a message

Feature Requests: Hide toolbar when not being used and lockdown

Tue, 07 Mar 2023 18:14:56 +0000

Hiding the toolbar, optimizing the space on the screen that is the game, really good for the small window i use for the emulator.
Attachment from VBA-M, it's extremely nice and happens when mouse hasn't hovered over the window for a second.

Lockdown simply prevents the ability to click and drag the window boarder to resize it.

image.png (Size: 32.18 KB / Downloads: 2)

Last build error

Sat, 10 Apr 2021 05:27:05 +0000

Problems running the latest update from git

The error displayed by the console is this:

Code:
mgba-qt: ../libepoxy/src/dispatch_common.c:858: epoxy_get_proc_address: La declaración `0 && "Couldn't find current GLX or EGL context.\n"' no se cumple.

Abortado (`core' generado)

Linux Manjaro

Problem with the speed option (bad english sorry)

Sun, 08 Mar 2020 12:17:28 +0000

Hello,

I'm here because I have a really annoying problem. When I use the TAB key for make my game run faster, my sound turned off. I tried everything to get my sound back but I didn't make it. Please, if somebody read this, help me ! (Sorry for the bad english, I'm not very good).

Feature request: save as Animated PNG?

Sat, 08 Feb 2020 21:36:31 +0000

I tried out the built-in recording/exporting function for the first time today and realized that a "save as Animated PNG" function could be a good intermediate between a full-fat lossless video recording and a 256 color-limited GIF. Now normally Animated PNGs with their full 24bit color palettes can get pretty large, but the GBA's 240x160 resolution is small enough and the graphics typically pixelated enough that animated PNGs of GBA games tend to actually compress pretty well, especially if they're optimized accordingly with regards to inter-frame compression (which I only mention because unfortunately there's quite a bit of APNG-creation software that creates completely unoptimized animations whereby each frame is fully stored as full-resolution PNGs, even if only one quadrant of the image actually updates) I don't know how useful the following would be for mGBA, but APNG Optimizer seems to be the go-to example of efficient inter-frame optimization and it does have a source available: https://sourceforge.net/projects/apng/fi...Optimizer/

Feature request: Configurable save directory

Fri, 10 Jan 2020 07:35:52 +0000

In many flash carts, there is a single save dir. I'd like the option to emulate this behaviour so that I can match the layout of my files and just keep the two in sync. Also, this way if I have multiple copies of the same ROM with the same file ane, but in different directories, I can have them save to the same file in the savedir. (I'm mostly looking to do this on 3DS and eventually switch.)

Fast forward

Sat, 15 Jun 2019 15:20:44 +0000

I was wondering if its possible to get faster fast forward

New dependencies

Thu, 13 Jun 2019 13:12:00 +0000

Hello again, I'm trying to compile mGBA in windows, I follow the instructions but to perform "cmake .. -G "MSYS Makefiles" tells me that it doesn't find the file libglu32.a. I can't find any package with a similar name, I looked in google and it seems to be a library of some openGL package. You could update the readme and add the new dependencies. And what would this dependency be?. Thank you very much

Edit: I just checked the terminal log and it seems that QT5 is the problem that looks for a dependency and doesn't find it. Do you know how I can solve this? Or is something wrong? What I'm doing to compile is what Readme from github says.

-- Checking for one of the modules 'libswresample'
-- Checking for one of the modules 'sdl2'
CMake Error at C:/msys64/mingw64/lib/cmake/Qt5Gui/Qt5GuiConfig.cmake:15 (message):
The imported target "Qt5::Gui" references the file

"C:/building/msys32/mingw64/x86_64-w64-mingw32/lib/libglu32.a"

but this file does not exist. Possible reasons include:

* The file was deleted, renamed, or moved to another location.

* An install or uninstall procedure did not complete successfully.

* The installation package was faulty and contained

"C:/msys64/mingw64/lib/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake"

but not all the files it references.

Call Stack (most recent call first):
C:/msys64/mingw64/lib/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake:45 (_qt5_Gui_check_file_exists)
C:/msys64/mingw64/lib/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake:70 (_qt5gui_find_extra_libs)
C:/msys64/mingw64/lib/cmake/Qt5Gui/Qt5GuiConfig.cmake:212 (include)
C:/msys64/mingw64/lib/cmake/Qt5Multimedia/Qt5MultimediaConfig.cmake:105 (find_package)
src/platform/qt/CMakeLists.txt:25 (find_package)

-- Configuring incomplete, errors occurred!