Skip to content

App Builder

The App Builder is a browser-based tool for writing, generating, and testing Cyber Fidget apps — no local setup required.

What it does

  1. Write or generate a C++ app using the code editor or build assistant
  2. Compile to WASM — builds your app to WebAssembly via GitHub Actions to support emulator
  3. Run in the emulator — test with on-screen buttons, slider, OLED, and LEDs
  4. Flash to hardware — compile for the ESP32 and flash OTA or via USB

Getting started

  1. Go to cyberfidget.com/build
  2. Sign in with your GitHub account (required for compilation)
  3. Write or generate your app code in the editor
  4. Click Compile Emulator to build for the browser, then Emulator to run it
  5. When ready, compile for hardware and flash to your device

Compile vs Emulator

Action What it does Speed
Compile Emulator Builds C++ to WASM via GitHub Actions ~1–2 min (first time, cached after)
Emulator Loads the compiled WASM and runs it in the browser Instant

These are intentionally separate steps. Compilation is slow (cloud build), but the emulator loads instantly from the cached WASM in IndexedDB.

Emulator features

The browser emulator maps all hardware to browser APIs:

  • Display — 128x64 canvas matching the OLED
  • Buttons — Keyboard shortcuts (Q/E/A/D/Z/C) or click on-screen
  • Slider — Draggable slider control
  • LEDs — Rendered as colored circles
  • Audio — Web Audio API for tones
  • Serial Monitor — Shows Serial.println() output

For full details, see the Browser Emulator page.

App lifecycle

Every app follows the same pattern:

void begin();   // Runs once when app starts
void update();  // Runs 50 times per second
void end();     // Runs once when app exits

See How an App Works for the full lifecycle and Concepts for how to use buttons, display, audio, LEDs, slider, and accelerometer.

See also

  • Browser Emulator — Detailed emulator guide, controls, and troubleshooting
  • Apps — Built-in app catalog and how to add your own
  • Concepts — Framework reference for all hardware features