KB1 - Pocket MIDI Keyboard Controller

A pocket-sized, feature-rich MIDI keyboard controller designed for the Polyend Tracker Mini. This first release delivers professional-grade performance controls, wireless configuration, and extensive musical capabilities in an ultra-portable package.

System Overview

The KB1 system consists of three integrated components working together to provide a complete MIDI performance solution:

Hardware

• 19-key velocity-sensitive keyboard with dual operating modes (Scale/Chord)
• 2 analog levers with push buttons for expressive control
• Capacitive touch sensor for additional expression
• Built-in mini speakers for audio monitoring
• ESP32-based with Bluetooth Low Energy connectivity
• Rechargeable battery with intelligent power management

Firmware (details)

• Dual keyboard modes: Scale (quantized to musical scales) and Chord (10 chord types with chord/strum options)
• Fully configurable controls with advanced interpolation curves and function modes
• 12 real-time performance sliders (CC 51-62) with bipolar/unipolar and momentary/latched modes
• 8 on-device preset slots for storing complete configurations
• Wireless BLE configuration and standard MIDI output

Web Configuration App (details)

• Browser-based configuration tool (no installation required)
• Real-time parameter editing over Bluetooth Low Energy
• 12-slider performance interface with mobile live mode
• Preset management with unlimited browser-stored configurations
• Works on desktop and mobile (Chrome, Edge, Opera)

Quick Start

1. Flash Firmware to Your Device

Download the firmware: Get the latest firmware from Releases (e.g., KB1-firmware-v1.1.1.bin)

Flash using ESPConnect (Recommended - No Tools Required):

1. Connect KB1 to your computer via USB-C

2. Open ESPConnect in Chrome/Edge: https://thelastoutpostworkshop.github.io/ESPConnect/

3. Click CONNECT and select your KB1 device from the serial port dialog

4. Backup Your Flash (Important!):

   • Click Flash Tools in the left sidebar
   • Click DOWNLOAD FLASH BACKUP
   • Save the backup file somewhere safe

   

5. Load Firmware File:

   • Click the firmware file upload field
   • Select the KB1-firmware-v1.1.1.bin file you downloaded
   • Flash offset should remain at 0x0

   

6. Flash the Firmware:

   • Check the box for "Erase entire flash before writing"
   • Click the FLASH FIRMWARE button
   • Wait for the flashing process to complete (~30-60 seconds)

   

7. Verify (Optional):

   • Click Serial Monitor in the left sidebar
   • Click START to view real-time output
   • Press keys on your KB1 to see MIDI note events

   

Video Tutorial: ESPConnect guide

2. Enable Bluetooth on Your KB1

IMPORTANT: Before connecting, ensure Bluetooth is enabled on your device.

To enable Bluetooth:

1. Hold both octave buttons (up + down) simultaneously for 3 seconds
2. Watch for LED confirmation:
   • Fast blinking (pink + blue LEDs) = Bluetooth enabled ✓
   • Slow blinking = Bluetooth disabled

Repeat the same process to toggle Bluetooth on/off at any time.

3. Configure Over Bluetooth

Launch the web app: https://pocketmidi.github.io/KB1-config

1. Click DISCONNECTED (top-right) and pair with "KB1"
2. Settings load automatically from device
3. Configure keyboard modes, controls, scales, and performance sliders
4. Click Save to Device to persist changes to flash memory

Performance Sliders: Switch to the SLIDERS tab for 12 real-time CC controllers. On mobile, rotate to landscape for fullscreen live mode.

iOS Users: Safari does not support Web Bluetooth. Download the Bluefy app from the App Store to access the web configuration app on iOS devices. Note: When using Bluefy, live mode automatically compensates for touch offset, and you may see one slider grayed out (11 remain active) - this is normal behavior for optimal touch accuracy.

Documentation

• Configuration App Guide - Complete web app documentation with usage examples
• Firmware Documentation - Technical details, features, and build instructions
• Hardware Design - Schematics and PCB files

Building from Source

Firmware (PlatformIO):

cd firmware
pio run --target upload

Web App (Vite + Vue 3):

cd KB1-config
npm install
npm run build

Detailed build instructions are available in the respective README files.

Gallery

License

• Software & Firmware: MIT License (see LICENSE)
• Hardware Designs: CERN Open Hardware Licence v2 – Strongly Reciprocal (see hardware/LICENSE-CERN-OHL-S.txt)

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Built for the Polyend Tracker Mini community