Overview

Major MIDI is a Daisy Patch SM firmware for playing Standard MIDI Files from SD card through a SoundFont 2 synth engine, with a compact front-panel UI, live MIDI input, loop playback, internal or external sync, and assignable CV/gate I/O.

This README is written as an operator guide first and a developer guide second, so it can be reused as source material for a website or user manual.

What Major MIDI Does

Major MIDI turns a Daisy Patch SM-based module into a multitimbral MIDI file player and live MIDI SoundFont instrument.

At a high level it gives you:

The system is designed around a small OLED and a minimal set of controls, so the workflow is fast once the front-panel logic is learned.

Quick Start

If you just want to get sound quickly:

1. Put at least one .mid file into 0:/midi.
2. Put at least one .sf2 file into 0:/soundfonts.
3. Insert the SD card and boot the module.
4. Open the main menu with a long encoder press.
5. Load a MIDI file.
6. Load an SF2.
7. Return to the performance screen.
8. Press Play.

If sync is set to external and no valid external clock is present, playback will not run. In that case either:

SD Card Layout

Major MIDI expects these folders:

0:/midi
0:/soundfonts

Example:

0:/midi/825.mid
0:/midi/beat_loop.mid
0:/soundfonts/microgm.sf2
0:/soundfonts/another.sf2

The browser ignores hidden AppleDouble files such as:

Boot Behavior

On boot:

The firmware does not background-save CV/gate changes while running, because SD writes during active streaming caused freezes. The safe save path is Save All.

Front Panel Overview

Major MIDI uses:

These controls do different things depending on the current mode:

Performance Screen

The performance screen is the default operating view.

Top line example:

STP 120 M001 B1 V

This means:

The bottom of the screen shows the visible 4 channels as columns.

Muted channels are shown with a leading *, for example:

*01

Zero values are shown as:

-

Performance Workflow

Banks

The 16 MIDI channels are grouped in banks of 4:

Press a bank button once to select that bank.

Quick Pages

The performance screen has 5 quick pages:

There are two ways to move between pages:

Example:

• press B1 once: bank 1, page stays as-is
• press B1 again quickly: page advances
• press B1 again quickly: page advances again

So if you are on bank 1:

• B1 once may show B1 V
• B1 twice more quickly may land on B1 R

If you then press B2 once:

• bank changes to 2
• page stays R

If you then press B3 quickly three times:

• bank changes to 3
• page cycles three times
• for example R -> C -> G -> V

Knobs

K1..K4 always control the 4 visible channels for the active quick page.

Examples:

The knob system uses pickup/hysteresis behavior, so a knob usually needs to cross the current stored value before it starts changing that parameter. This prevents abrupt jumps after bank/page changes.

Play Button

Play toggles:

If external sync is selected and there is no valid external clock, the transport will not free-run.

Encoder Turn

In performance mode, turning the encoder changes BPM.

BPM range:

If a song BPM override or CV BPM control is active, that affects the effective playback tempo.

Shift Actions

The encoder press acts as shift in performance mode.

Available combos:

Mute All Behavior

Mute All is not a separate global mute engine anymore.

Instead, it directly toggles the muted flag on all 16 channels:

This means mute state remains per-channel and visible everywhere.

Mute Mode

Mute mode is meant for fast channel muting without touching the mix values.

While in mute mode:

Important:

Loop Edit

Loop edit is a quick front-panel way to set loop boundaries.

In loop edit:

Under the hood, Major MIDI keeps more precise loop metadata than the coarse performance controls expose. Loop playback was reworked to avoid seam restarts and instead pre-schedule the next loop cycle, which is why loop timing is now much more stable than earlier versions.

Main Menu

Open the main menu with a long encoder press.

Main menu items:

Menu controls:

Load MIDI

This page shows the available .mid files.

Behavior:

Load SF2

This page works the same way as Load MIDI, but for SoundFonts.

FX Settings

This page adjusts the global FX parameters used by the synth engine.

Parameters:

These are global synth settings, not per-channel send levels.

Per-channel reverb and chorus amounts are on:

Song Settings

This page stores song-level metadata in the current MIDI file.

Parameters:

This data is stored in the custom MMID meta-event block.

What Song Settings Persist

Current song save data includes:

SF2 Settings

This page is the deeper per-channel and synth configuration page.

Parameters:

Voices

Voices sets the maximum synth voice count.

Range:

This directly affects CPU load. If you hear crunching at high polyphony:

Channel

Selects which MIDI channel the rest of the SF2 page edits.

Program

Program behavior is important:

Program overrides are also available from the live performance G page.

Transpose

Global transpose for melodic channels.

Drum channel handling remains separate so channel 10 behaves as expected for kits.

CV/Gate

Phase 1 CV/gate routing is implemented.

The page dynamically hides irrelevant options. For example:

CV Inputs

Available inputs:

Modes:

CV Input: MasterVol

Maps CV to overall output gain.

CV Input: BPM

Maps CV to tempo.

Current range:

CV Input: Ch CC

Sends a continuous CC to the selected channel.

Gate Outputs

Available outputs:

Modes:

Sync

Outputs regular pulses at:

Reset

Outputs a short pulse every measure.

Ch Gate

Outputs a gate while the selected channel has active notes.

CV Outputs

Available outputs:

Modes:

Pitch

Pitch mode is monophonic per selected channel.

Priority options:

CC

Outputs the current CC value for the selected channel and CC number.

Save All

Save All is available from the main menu and includes a confirm/cancel screen.

Saved data:

Safety behavior:

This is currently the safe persistence path for CV/gate settings.

Sync

Major MIDI supports:

The sync source switch is on MCP23017 GPB1.

Internal Sync

When the switch is up:

External Sync

When the switch is down:

Current external sync sources:

Priority:

If external sync is selected and no valid external clock is present:

External Sync Notes

External sync behavior has improved substantially, but this is still one of the more complex areas of the firmware. In particular:

• clock drop/reacquire behavior is still something to keep testing
• gate pulse expectations matter
• MIDI start/continue/stop and gate clock behavior do not map perfectly to every external setup

MIDI Input

Supported live MIDI inputs:

Live MIDI is serviced on the fixed control/audio path for better timing than simple main-loop polling.

Handled message types:

Program Handling

Program handling now works in three layers:

1. file program changes from the MIDI file
2. restored file program state on seek / loop start
3. user program override on top

This matters because Major MIDI can:

The firmware now restores the latest file program state before a seek point, then applies the user override if one exists.

Performance Program Page

The G quick page is the fast live program page.

Behavior:

Looping

Looping in Major MIDI is not a naive stop-and-restart seam anymore.

Current loop design:

This is why loop playback is now much tighter than earlier revisions.

Performance Tuning Notes

If you are hearing crunching or overload:

The synth engine also uses:

But max voices is still the main operator control for CPU load.

File Saving and Persistence

What Saves Per MIDI File

Song metadata in the MIDI file can include:

What Saves Globally

Currently:

What Does Not Background-Save

CV/gate config is not auto-saved during runtime because SD writes collided with active SF2 and MIDI streaming and caused freezes. Save All is the safe user-facing save flow.

Hardware Mapping

Current firmware assumptions match the tested hardware used during development.

Build

From the repo root:

make -C DaisyExamples/patch_sm/SF2MidiPlayer

Artifacts:

Typical Workflows

Play a Song

1. Long-press encoder to open the menu.
2. Load a MIDI file.
3. Load an SF2.
4. Return to performance.
5. Press Play.

Mix the Visible 4 Channels

1. Choose the bank with B1..B4.
2. Cycle to the page you want:

• V
• P
• R
• C

1. Turn K1..K4.

Change Instruments for a Bank

1. Go to the desired bank.
2. Cycle to page G.
3. Turn K1..K4 to set programs for the 4 visible channels.

Set a Loop and Save It

1. Enter Loop Edit or Song Settings.
2. Set the loop start and loop length.
3. Save the song settings to the MIDI file.

Configure a Clock Output

1. Open CV/Gate.
2. Set Gate Out 1 or Gate Out 2 to Sync.
3. Choose a resolution.

Save Your Setup

1. Stop playback.
2. Open main menu.
3. Choose Save All.
4. Confirm.

Troubleshooting

The song will not start in external sync mode

Possible causes:

I changed a program and other channels changed unexpectedly

This was previously caused by a synth-wide reset path tied to voice-count reapplication. The current firmware only reapplies max voices when the value actually changes.

CV/Gate menu changes used to freeze the module

That was caused by background SD writes during active streaming. Runtime autosave was removed and replaced with explicit save flow.

The loop used to hang notes

Loop wrap now flushes still-active notes at the seam before continuing the next cycle.

Playback crunches at high polyphony

Reduce:

External sync is still not perfect for my setup

That area is still under active iteration. Test with a known-good clock source first and verify whether your external gate clock is behaving as expected.

Developer Notes

Major MIDI evolved from a simpler SF2 MIDI player into a more structured UI-driven firmware. The current architecture separates:

Important implementation notes:

License / Project Context

This project expects to live at:

DaisyExamples/patch_sm/SF2MidiPlayer

so it can build against the local libDaisy and DaisySP trees in this repository layout.