Hi,

I am somewhat new to GBA dev, I only ever touched features mentioned in the TONC tutorials.

I would like to use the serial port to communicate between my ROM and the emulator. Is it possible with mGBA ? Do you have any reference on how to do it ? I would assume it requires using the Lua scripting capabilities.

Thanks !

What I am trying to do.
Drawing a hexagonal grid looks better with a 7x8 tile, so during the horizontal blanking interval I am trying to skip the 8th row of every tile. There are 7 drawn rows on each tile and the 8th row that is completely black to make it obvious if something isn't working. The horizontal blanking code is not running as the tiles and background are setup. Once everything is setup the horizontal blanking code is active.

Description of the Symptom.
It reliably skips the 8th row on a Gameboy Advance SP and the visual boy advance emulator, but on mGBA it is showing the 8th row on some tiles on the right edge of the screen. For some reason the row that the cursor is on never has the problem.

My thought.
The thing that would make sense to me is that the horizontal blanking is being triggered early. This is supported by the line the cursor is on never having the issue. The cursor being drawn would delay the horizontal blanking trigger by just a hair preventing it from running the horizontal blanking code early. I tried to see if my code was the issue but I didn't find anything to try to do differently.

Relevant Source Code Pseudo Code:
Setup
0xFF40 |= 0x02
0xFF41 = 0x08
0xFFFF = 0x03
Horizontal Blanking
shift_counter = shift_counter + 1
if(shift_counter == 7) {
shift_counter = 0
horizontal_shift = horizontal_shift + 4
vertical_shift = vertical_shift + 1
0xFF42 = vertical_shift
0xFF43 = horizontal_shift
}


Specifications
mGBA: 0.10.5 flathub system-wide flatpak
OS: Pop!_OS 22.04 LTS (64-bit)
GNOME Version: 42.9
Windowing System: X11
CPU: Intel® Core™ i7-9750H CPU @ 2.60GHz × 12
Graphics Card: Mesa Intel® UHD Graphics 630 (CFL GT2)

Rom and Symptom Image are Attached.
It didn't let me load the rom directly so I changed the file type to txt. Change it back to .gb before using.

Attached Files

  code_rom.txt (Size: 32 KB / Downloads: 2)
  Screenshot from 2025-07-05 16-11-47.png (Size: 15.19 KB / Downloads: 3)

Hello,

I recently started using mGBA and I was hoping that I could transfer my VBA saves to mGBA. The .SAV file is in the same folder, with the same name as the ROM, however for some reason, whenever I boot up the game, the game starts anew, clearly failing to recognise the .SAV file as being present. Could it be thew file size? From what I understand, mGBA creates 32kb .SAV files, whereas the file in the folder is 128kb. If my presumption is correct, how could I go about changing the file size, if possible? If not, what could be causing the issue?

for some reason randomly when playing my game will suddenly freeze and say "not responding" it didnt do this a couple of months ago but now all of a sudden it is and its completely ruining the experience for me can anyone help me?

Hi everyone!

I’m having trouble trying to start the VS mode of Tactics Ogre: Knight of Lodis on mGBA.

I use the "New multiplayer window" function to launch a second instance of the emulator. I load the ROM in both instances and start the VS mode from two different save files. However, the two emulator instances don’t seem to recognize each other…

Do you have any suggestions?

Thanks a lot in advance to anyone who replies.

Hello, I foolishly loaded my near completion gba game file in mGBA. I typically play the game on my ez flash cart but in trying mGBA it split the file into the base game and a “.sav” file. Effectively ruining the game for both. Can anyone point me in the right direction to fix this please? This is all I play.

Why does it make these sounds when I load up the bios in mGBA? it works fine in other emulators.
here's a link to the video, since it doesn't allow me to attach a video: https://file.garden/ZiXiiiIWlR7-wknI/mGB...-11-24.mp4 (idk if links are allowed, as I couldn't find a rules page for this)

I'm playing a Emerald based hackroom on multiplayer and the second player can't save without freezing both layers. I have try differents config and a dev build but i couldn't fix it

As I use GlosSI to make mGBA to work with steam input. But ViGEmBus is now unsupported program for Windows 10 and 11 and there are no alternatives. So I'm stuck with using mGBA on retroarch and I added non-steam windows retroarch to steam library to use with steam input with various of my controllers like NSO snes controller for Nintendo switch. Retroarch doesn't have hi-res mode for mGBA but I can't use mGBA exe program because steam input doesn't work with it.

Steam input works for duckstation, pcsx2, dolphin, retroarch, mame and rpcs3.
It doesn't work for mGBA and melonDS. Azahar 3ds emulator are also fixing this bug.
I also have to use melonDS through retroarch as melonDS exe program doesn't work with steam input.

Hey Guys, my new Controller arrived today and I have huge mapping problems with it
with my PS4 Controller, everything was nice

A lot of inputs give the 2 inputs at the same time and I cannot delete some of it at all. Leading to problem with multiple inputs at the same time.

The analog Sticks aren't working at all like intended
Doing a “left” input with the analog stick results in a “R1” input, and deleting the analogs does nothing.

The Controller features 4 Modes

x-input (right now)
d-input
switch mode
apple mode

In another mode, I guess D-input (not sure) I had an issue with pressing “L3” resulted in walking leftwards and “R3” resulted in walking rightwards.

Attached Files

  Screenshot 2025-04-29 161749.png (Size: 60.3 KB / Downloads: 3)