A compact all-in-one input board with 16 buttons, an on-board multiplexer, 8 NeoPixel LEDs, and a single 10-pin IDC connector—everything on one PCB.
Overview
The Double Array Button Board is the most self-contained input module in the legacy platform. Unlike the Extension Board 1+2 pair (which splits 16 channels across two separate PCBs), this board places all 16 buttons and the multiplexer on a single board, making it ideal for applications where space is limited or where a simple plug-and-play solution is preferred.
It connects directly to the MIDI Controller Board through a standard 10-pin IDC ribbon cable, providing a clean single-cable installation.
Key Features
- 16 buttons — All input channels populated on a single board
- On-board 74HC4067 multiplexer — Self-contained scanning, no external MUX needed
- 8 WS2812 NeoPixel LEDs — Visual feedback in daisy-chain configuration (one LED per two buttons)
- 10-pin IDC connector — Single ribbon cable connection to the MIDI Controller Board
- Debug channels — All multiplexer channel states pinned out for troubleshooting
Comparison: Double Array vs. Extension Board Pair
| Feature | Double Array | Extension 1+2 |
|---|---|---|
| Total inputs | 16 | 16 |
| Number of PCBs | 1 | 2 |
| On-board MUX | Yes | Yes (on Board 1) |
| NeoPixel LEDs | 8 (shared) | 16 (one per key) |
| Connection | 10-pin IDC | Ribbon to controller |
| Best for | Compact builds, pistons | Stop tabs, larger arrays |
Typical Applications
- Thumb pistons — 16 combination memory buttons mounted below the manuals
- General pistons — Full and divisional piston rows
- Toe piston arrays — Foot-operated buttons beneath the pedalboard
- Control panels — System controls (transpose, temperament, memory level)
Layout
The 16 buttons are arranged in a double row (2×8) for efficient panel mounting:
┌─────────────────────────────┐
│ [1] [2] [3] [4] [5] [6] [7] [8] │
│ │
│ [9] [10][11][12][13][14][15][16] │
│ │
│ ○ ○ ○ ○ ○ ○ ○ ○ │
│ (NeoPixel LEDs) │
│ │
│ [74HC4067] [IDC-10] │
│ [AUX Pins] │
└─────────────────────────────────────┘
Manufacturing
Single-board design on a standard 2-layer PCB. All components use through-hole or common SMD packages. The 10-pin IDC connector accepts standard flat ribbon cable for easy wiring.