RB SWITCH

RB Switch

The RB Switch is a three-button Bluetooth Low Energy (BLE) accessibility switch. It presents itself to a computer, tablet, or phone as a standard Bluetooth keyboard, so it works with Switch Control (iOS/iPadOS), Switch Access (Android), and any app that accepts keyboard input.

At a glance

Quick start

1. Power the switch from USB-C or its battery.
2. Pair RB Switch in the device's Bluetooth settings.
3. Press each button in a text field: Left, Enter, Right.
4. Set up Switch Control (iOS/iPadOS) or Switch Access (Android) from the guides below.

Important for Android users: Android's Switch Access is a separate app you install/update from the Google Play Store, and its setup wizard only offers a one-switch or two-switch configuration. It does not offer a third switch by default. Using the RB Switch's third button on Android requires one extra step beyond the wizard. This is different from iOS/iPadOS, where all three buttons can be assigned directly in the normal setup flow. See Android Switch Access and iOS/iPadOS Switch Control before you configure a device.

Production firmware

The production firmware is:

firmware/RB_SWITCH_firmware/RB_SWITCH_firmware.ino

Button mapping

Each button press produces one key press followed by one key release. Holding a button does not repeat the key. A press made while no host is connected is ignored.

Building the firmware

1. Install the Arduino IDE, the ESP32 Arduino core by Espressif, and NimBLE-Arduino 2.x.
2. Select ESP32S3 Dev Module and set USB CDC On Boot to Enabled.
3. Open the .ino file, click Verify, then Upload over a data-capable USB-C cable. If the upload does not start, hold BOOT, tap RESET, release BOOT.
4. Open the Serial Monitor at 115200 baud.

See Firmware for details.

Documentation

Published documentation: https://mrhunsaker.github.io/RB_SWITCH/

Two printable Word documents are also available. Both are generated from the matching page in docs/.

Troubleshooting at a glance

The full guide, including board-level checks for technicians, is in Troubleshooting.

Hardware

The current board uses:

• ESP32-S3-MINI-1-N4R2
• Three Omron B3F-series tactile switches
• USB-C power/programming connection (native USB, no USB-to-serial chip)
• Single-cell Li-Po battery connection and MCP73831 charger
• TPS63001 3.3 V buck-boost regulator
• Battery-voltage sensing (not yet used by the firmware)
• MCP73831 charge-status LED
• Reset and boot buttons, with a 10 kΩ pull-up and 1 µF capacitor on the reset line

Hardware source files are in electrical/, bom/, and mechanical/.

Before ordering boards: the files in electrical/mechanical_switch/gerbers/ and the PCB images in electrical/mechanical_switch/diagrams/ come from an earlier layout. Re-export them with create_gerber.ps1 and check the CPL orientation of U1, REG1, D1, J_USB1, and L1 in the fab's preview.

Production scope

The production design has three mechanical switch inputs only. It does not implement touch sensors, proximity sensors, NeoPixel/RGB indicators, mono-jack inputs, or the earlier F-key input mapping.

The charge-status LED (D1) is controlled by the battery charger and is not a programmable RGB LED.

Repository layout

Documentation source

docs/ is the published GitHub Pages source.

documents/ contains the same documentation in a packaging-friendly directory. Keep the two documentation sets synchronized when documentation changes.

After editing docs/, run:

python3 tools/sync_documents.py
node tools/build_docx.js

The first script rewrites documents/ from docs/. The second rebuilds both Word documents (RB_Switch_Paraprofessional_Setup_Guide.docx from docs/setup.md and RB_Switch_Evaluation_Package.docx from docs/evaluation-package.md). It needs Node.js and the docx package (npm install docx). Pass setup or evaluation to build just one. See tools/README.md.

GitHub Pages and enclosure QR code

Publish docs/ with GitHub Pages. The enclosure QR code should point to the published documentation home page. See QR Code.

Contributing

Contributions to firmware, hardware, and documentation are welcome. See CONTRIBUTING.md for project structure, how to propose a change, and pull request expectations, and CODE_STYLE.md for formatting and naming conventions. Please review CODE_OF_CONDUCT.md before participating.

Security

To report a suspected security or safety issue, see SECURITY.md rather than opening a public issue.

Changelog

See CHANGES.md for a history of notable changes.

License

This project is licensed under the APACHE 2.0 License— see LICENSE for the full text, including a note on hardware-specific licensing alternatives.