This Midilooper has been created with help of chatgpt and later Cursor. It has proven to be a great tutor to help me guide and understand every added feature's logic. It saved me a lot of time looking for the correct approach or answers on how to tackle things.
The main inspiration was taken from this minimalistic 4 track looper using only 2 buttons and 4 digits: https://iestyn-lewis.github.io/4by8/
- 1x Teensy 4.1
- 2x momentary button
- 1x liquid lcd display 16x2
- 1x 6N137
The midi circuit is based on https://www.pjrc.com/teensy/td_libs_MIDI.html
- 4 Midi Tracks
- 192 PPQN internal clock for live recording
- 24 PPQN midi Sync
- 16x2 information display
- 2 button operation
- 99 Undos per track
- Automatic saving of Loops on SD card
- Reload last used state and loops on startup
| Press # | From State | To State | Symbol Change | Key Action |
|---|---|---|---|---|
| 1× (single) | TRACK_EMPTY |
TRACK_RECORDING |
– → R | startRecording() |
| (internal) | TRACK_RECORDING |
TRACK_STOPPED_RECORDING |
(not shown) | stopRecording() |
| (internal) | TRACK_STOPPED_RECORDING |
TRACK_PLAYING |
(not shown) | startPlaying() |
| 2× (single) | TRACK_PLAYING |
TRACK_OVERDUBBING |
P → O | startOverdubbing() |
| 3× (single) | TRACK_OVERDUBBING |
TRACK_PLAYING |
O → P | stopOverdubbing() |
| Double | no change | no change | no change | undoOverdub() |
| Long | (any) | TRACK_EMPTY |
→ – | clearTrack() |
| Press # | From State | To State | Key Action |
|---|---|---|---|
| 1× (single) | Selected Track | Select next track | setSelectedTrack() |
| Long | (any | TRACK_MUTED | isAudible(0) |
- Retroactive bar-quantized recording (record complete bars, but allow earlier recording start)
| 1 2 3 4 | 1 2 3 4 |
^ You press record here (beat 3)
^ You press stop here (beat 4)
New Loop ready for overdub to add the notes in the first bar.
| 1 2 3 4 | 1 2 3 4 |
| Module | Key Data | Connected Modules | Purpose |
|---|---|---|---|
ButtonManager |
Button press type, millis() |
TrackManager, ClockManager |
Triggers recording/playback/overdub/mute/clear actions |
TrackManager |
selectedTrack, masterLoopLength |
Track, ClockManager |
Manages track states and coordination, handles quantized events |
Track |
MidiEvent, NoteEvent, startLoopTick, loopLengthTicks |
N/A | Stores and manages MIDI/Note data, performs playback and recording |
ClockManager |
currentTick |
All other modules | Provides global timing for sync and quantization |
DisplayManager |
— | TrackManager, Track |
Displays NoteEvents, loop status, and other track information |
Some of the chat can be viewed here of my journey.
MidiLooper (First one. Got really messy with too many workarounds, but with auto load/save functionality from SD) https://chatgpt.com/share/680a4839-6720-800b-ae73-9aff16f6e41f
MidiLooperV2 (Simpler switch logic for tracks, focussing on workflow logic) https://chatgpt.com/share/680e999a-c860-800b-a079-9862a59f1e89
MidiLooperV3 (Started off from a framework in C++, hope it will be more stable to use) https://chatgpt.com/share/680e98f9-2a64-800b-abb2-4e1bd359c90f
Developing the SSD1322 circular DMA logic was a lot of fun using Cursor. It was really helpfull to have an LLM model explain someone elses 2000+ lines of code in how the logic worked I wanted to port to this display.