102 lines
4.2 KiB
Markdown
102 lines
4.2 KiB
Markdown
# FCB1010 Looper Pedal - Project Specification
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## System Overview
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A looper pedal system using a modified Behringer FCB1010 MIDI foot controller, Behringer UMC404HD audio interface, Raspberry Pi with TFT display (215x135mm).
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The system provides a 5x5 matrix of loop tracks organized in columns and rows, with real-time visual feedback.
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## Hardware Components
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- **Behringer FCB1010**: MIDI foot controller with 10 footswitches (1-10), UP/DOWN buttons, and 2 expression pedals
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- **Behringer UMC404HD**: Audio interface for input/output
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- **Single Board Computer**: Running Linux
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- **TFT Display**: 215x135mm color display, no touchscreen
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- **Audio**: JACK audio connect kit
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## System Architecture
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### Two-State Operation
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1. **Menu State**: Configuration and management functions
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2. **Performance State**: Recording and playback matrix
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### Matrix Organization
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- **5 Columns**: Synchronized recording and playback for each column
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- **5 Rows**: Individual tracks within each column
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- **25 Total Cells**: Each cell can contain one audio loop
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- **Column-based Timing**: First recording in a column sets the beat count for all tracks in that column
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## Interface Design
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- **Metronome**: Moving indicator that pulses when in center
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- **Progress Bars**: Show current position in each column with beat divisions
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First recording behavior:
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- Progress bar fills during beat 1, then stays full
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- Additional beats appear as sliding segments (right-to-left)
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- **Active Row**: Increased border with
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- **Selected Cell**: Switched border and background color
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- **Track States**:
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- `---`: Empty cell (dark background)
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- `READY`: Recorded, ready to play (green)
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- `PLAY`: Currently playing (blue)
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- `REC`: Currently recording (red)
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- `SOLO`: Solo mode active (orange/amber)
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- **Volume Bars**: Small bars under each cell showing track volume
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## Button Mappings
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### Menu State
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- **Button 1**: Tap Tempo
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- **Button 2**: Enable/Disable Click Track
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- **Button 3**: Not used
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- **Button 4**: Not used
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- **Button 5**: Clear current column
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- **Buttons 6-10**: Column selection (1-5)
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- **UP/DOWN**: Switch to Performance Mode
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- **Expression Pedal A**: Click track volume
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- **Expression Pedal B**: Master volume
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### Performance State
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- **Button 1**: Record/Arm
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- **Button 2**: Play/Mute current track
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- **Button 3**: Solo current track
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- **Button 4**: Overdub on current track
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- **Button 5**: Clear current track
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- **Buttons 6-10**: Column selection (1-5)
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- **UP/DOWN**: Navigate rows (switch between track rows), return to Menu when at top or bottom
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- **Expression Pedal A**: Current track volume
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- **Expression Pedal B**: Master volume
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## Operational Behavior
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### Recording Workflow
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- **First Recording in Column**: Sets beat count for entire column, records until stopped
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- **Subsequent Recordings**: Auto-sync to established column length
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- **Record Button Stop**: Recording stops, cell starts playing
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- **Stop Button Stop**: Recording cancelled, previous state restored
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- **Overdub Button Stop**: Recording continues for next loop, overdubs on previous content
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### Timing and Synchronization
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- **All actions sync to the beat**: Start/stop occurs at metronome center position
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- **Column Switching**: Only when not recording, immediate switching to selected column
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- **Tempo Changes**: Only allowed when all tracks are cleared
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- **Recording Start**: Synced to column start if column playing, otherwise next beat
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### Solo Functionality
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- **Solo Activation**: Press Solo button on any track
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- **Solo Indication**: Cell shows `SOLO` state in orange/amber color
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- **Multiple Solo**: Additional tracks can be added to solo group
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- **Solo Play**: Activates solo tracks + any tracks showing `PLAY` state
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- **Solo Stop**: Stops entire column
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- **All Solo Actions**: Synced to next beat
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### MIDI Implementation
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- **Startup**: Send SysEx configuration to FCB1010 for proper button/pedal mapping
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- **Expression Pedals**: Set volume on change
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- **MIDI Feedback**: Send click track to sync with other systems
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### State Management
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- **Startup Behavior**: Load last audio tracks and configure FCB1010
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- **Column Consistency**: Recordings automatically match column beat count
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- **State Validation**: Prevent invalid operations (e.g., switching columns while recording) |