mGB (ts mod*)

mGB is a Gameboy cartridge program (You need a Flash Cart and Transfer hardware) That enables the Gameboy to act as a full MIDI supported sound module. It works with the old DMG Gameboy as well as GBC/GBA.

More information about Arduinoboy

*NOTE: This is an unofficial fork of the original mGB

Changes:

• The code has been updated to be closer to idiomatic GBDK-2020
• Converted much of the assembler back into C code to invite more features and bug fixes

Building mGB

Follow the GBDK-2020 instructions and unzip v4.3.0+ into the gbdk/ folder. Then run make:

cd Source

make           # fast compile
make DEBUG=1   # enable debug symbols
make RELEASE=1 # slower compile but faster on device
make clean     # clean up the build directories

Change Log

• 08/23/24 v1.4.0-ts
  • Fixed some synth frequencies playing incorrect notes (now it will be silent for notes that are too high or low to play on the synth)
  • Fixed other various invalid memory accesses
• 07/16/24
  • Project updated to build with GBDK-2020 v4.3.0
  • Fixed cartridge type, missing name in rom header, and CGB flag
• ^^07/16/24 - UNOFFICIAL FORK^^
• 06/26/15
  • Project has been moved to GitHub along with sourcecode.
• 12/21/12 1.3.3
  • Fixed a bug with the new pitchbend resolution
  • Optimized some of the pitchbend routine
• 12/20/12 1.3.2
  • Increased pitchbend resolution
• 12/19/12 1.3.1
  • Fixed PU1 Envelope retrigger bug.
• Feb 2 2009 1.3.0
  • Rewrote 90% of code into assembly for much faster performance- especially noticeable on DMG.
  • Changed note behavior. Removed Monophonic note memory to increase performance.
  • Envelope does not retrigger if the notes overlap and have the same velocity- Good for arpeggios / broken chords.
  • Note off has a slight delay so immediate retrigged notes don't cause "clicking" effect due to turning off the synth.
  • Added screen off mode for great signal-to-noise ratio, longer battery life, and better performance on DMG. (To toggle the screen mode hold Select and press A.)
  • Created back-end routine that prioritizes processes for better performance.
  • Added 8 "noise" shapes to the Wav synth for more interesting effects.
  • Made Wav pitch sweep stable and changed it so it glitches out at values above 8. :D
• Nov 5 2008 Version: 1.2.4
  • Fixed small bug with the indicator arrow, it was offset vertically a bit.
  • Fixed bug with unexpected behavior with large PB Ranges
  • PB Range Max is now 48 notes. (hehe)
  • Octave Shift max is now -2/+3
  • Added some Octave shift logic. If the current note is greater than what the GB can play due to octave shifting, it will select the lower octave note, so no off key notes will play.
  • Added Gameboy Color fast-cpu mode- better performance with newer Gameboys.
• Oct 28 2008 - Version: 1.2.3
  • Added Note markers above synth number, so you can tell if the synth is on. ;)
  • Added PB wheel reset to MIDI panic (Start button)
  • Code more efficient (I'm sure there is still more to do here)
  • nitro2k01 @ http://gameboygenius.8bitcollective.com rewrote my gamejack serial function to make it as fast as possible. THANKS!!
• Oct 25 2008 - Version: 1.2.2
  • Added Program Change messages to mGB
  • Rewrote MIDI data input for mGB. (Rewrote the function in ASM to make it faster)
  • Added Controller Priority. While changing parameters on the gameboy itself, MIDI messages will not overwrite your changes while your editing them. This is a good live mode feature
• Oct 23 2008 - Version: 1.2.1
  • Found & Fixed various bugs in 1.2.0
  • Changed help text. Made it more clear.
• Oct 23 2008 - Version: 1.2.0
  • Change interface a bit
  • Added presets
  • Optimized code
• Oct 20 2008 - Version: 1.1.0
  • Added Interface
  • Changed Wav CCs Around to make more consistent with the Pu Synths.
• Oct 4 2008 - Version: 0.1.2
  • Fixed bug with Wav Synth hanging after sequencer stop.
  • Fixed bug with Wav Synth not resetting monophonic keyboard note triggers

Button Shortcuts

• Start: MIDI Panic
• Select + Dpad: Select multiple synths for editing.
• Select + A: Toggles the screen on or off, better battery life, less noise, and faster response.
• Select + B: Copys all parameters on screen while cursor is not on preset number.
• B: Pastes all parameters while cursor is not on preset number
• A + Dpad: Change parameter value
• To load/save presets, put the cursor on the "PRESET" number, and hit B for load, Select+B to save

MIDI Implementation

Note: the name and number at the bottom left of the screen indicates the midi CC of the selected parameter.

PU1 - MIDI CH1

Control
Program Change	1 to 16
PB: Pitch bend	up to +/- 12
cc1	Pulse width - 0,32,64,127
cc2	Envelope mode - 0 to 127, 16 possible steps
cc3	Pitch sweep
cc4	Pitchbend Range
cc5	Load Preset
cc10	Pan
cc64	Sustain- Turns off note off. <64 = off, >63 = on

PU2 - MIDI CH2

Control
Program Change	1 to 16
PB: Pitch bend	up to +/- 12
cc1	Pulse width - 0,32,64,127
cc2	Envelope mode - 0 to 127, 16 possible steps
cc4	Pitchbend Range
cc5	Load Preset
cc10	Pan
cc64	Sustain- Turns off note off. <64 = off, >63 = on

WAV - MIDI CH3

Control
Program Change	1 to 16
PB: Pitch bend	up to +/- 12
cc1	shape select : 16 possible on a 0 to 127 range
cc2	shape offset : 32 possible on a 0 to 127 range
cc3	Pitch Sweep speed. 0=Off, 1-127 speed.
cc4	Pitchbend Range
cc5	Load Preset
cc10	Pan
cc64	Sustain- Turns off note off. <64 = off, >63 = on

NOISE - MIDI CH4

Control
Program Change	1 to 16
PB: Pitch bend	up to +/- 24
cc1	Pulse width - 0,32,64,127
cc2	Envelope mode - 0 to 127, 16 possible steps
cc5	Load Preset
cc10	Pan
cc64	Sustain- Turns off note off. <64 = off, >63 = on

POLY MODE - MIDI CH5 - Plays Pu1/Pu2 and Wav in poly

Control
Program Change	1 to 16
PB: Pitch bend	up to +/-2
cc1	See cc1
cc5	Load Preset
cc10	Pan
cc64	Sustain- Turns off note off. <64 = off, >63 = on