STEPPER: A new 16-step sequencer for the GBA

Hello folks!

I’ve just released the first version of STEPPER, my new 16-step sequencer for the Game Boy Advance (GBA). It has access to the original 4 channels of the DMG (2 square waves, 1 programmable wave and 1 noise channel). You have 4 banks of 8 patterns available and the patterns can be chained (Only one at a time for now but this could change in the future).

Here is a little demo:

The project is open source and you can get the GBA rom on its page starting at 0 bucks.

I hope you like it and let me know if you try it out and what you come up with! :smiley:



What a wonderful demo. Lovely clear interface, looks super fun and quick to use!
Congrats on the release!

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Thank you for your lovely words happy you liked it! Let me know if you end up playing with it :slight_smile:

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Seems to be working on hardware (On the 3DS at least, using a GBA injector):


For sneaky office comrades, it works here too:


Excited to try this! Great to see any new GBA music roms

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cheers! hope you like it :slight_smile:

STEPPER v1.3 is out! I’ve wrote about the main changes here:

Biggest changes are

  • Quick saving with SELECT + START
  • Per channel parameter adjustment and note transposition
  • SELECT + L/R to adjust notes by octave or BPM by increments of 10

Volume should be way louder than on v1.0 and I included a .cia for loading directly on 3DS consoles.

I’ve also tested it on a GBA SP with a cheap flash cart and works great. I’m waiting for an Everdrive to be delivered to be able to do more hardware experiments. Particularly I’m interested to see if I can get a sort of CV gate out working using a modified GBA Link cable.

If you try this update and find any issues, please let me know!



Have not had a chance to try it out proper, but can report it looking good on an Analogue Pocket with an openFPGA GBA core as well.

Edit: seems to kill audio for that voice when I change some parameters on the top. Have not dug in though.


Thanks for testing it! Let me know if you manage to find how to cause the audio issue and I’ll see if I can reproduce it on my end.

In any case check that the volume envelope is set properly and see if the issue persists with sweep disabled (num 0 time 0).

Studio is a bit of a mess right now, but finally have a moment to give it a spin :metal:

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glorious! there is a kind of order in the chaos there haha

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I’m preparing a new version of STEPPER that should come out this week (hopefully). It will include link cable and audio sync, theming support and some bugfixes and misc improvements.

I already have a proof of concept for the link cable sync working. Here you can see a GBA clocking a PO-20:

Note that the gate output is of 3.3V, which is enough to trigger the Gate In on my Microbrute and control some other CV parameters but I can’t guarantee it will work with all Eurorack modules or CV capable synths without some amplification:

As for the theming support I currently have 4 default themes in place but I’m open for feedback and contributions from the community:

If you want to contribute you can propose your RGB555 colors (0-31 instead of 0-255)

Currently each theme is made of 6 colors:

  • Background
  • Foreground
  • Accent 1 (Cursor)
  • Accent 2
  • Accent 3
  • Disabled (Background elements)