Alloy

Alloy is a JavaScript framework for building Pebble apps, based on the Moddable SDK. Alloy provides developers a mix of standard Web APIs, standard Embedded JavaScript APIs from ECMA-419, and dedicated Pebble OS APIs. It allows you to write apps using modern JavaScript (ES2025, ES6++) with powerful UI frameworks and access to Pebble hardware features.

Platform Support: Alloy currently supports Emery (Pebble Time 2) and Gabbro (Pebble Round 2).

Key Features

• Modern JavaScript: Write apps using ES modules, classes, async/await, and other modern JavaScript features
• Two UI Frameworks: Choose between Piu (declarative, component-based) or Poco (procedural, low-level graphics)
• Hardware Access: Full access to accelerometer, battery, buttons, compass, and other Pebble sensors
• Network Communication: Built-in support for HTTP requests, WebSockets, and watch-phone messaging
• Persistent Storage: Simple APIs for storing data locally using localStorage, key-value storage, or files

Getting Started

To create a new Alloy project:

$ pebble new-project --alloy my-app

This creates a new project with the standard Alloy structure:

my-app/
  src/
    embeddedjs/
      main.js           # Watch code (runs on Pebble)
    pkjs/
      index.js          # Phone code (for networking, location)
    c/
      mdbl.c            # C code as entry point for embeddedjs (usually no need to modify)
  resources/            # App resources (images, fonts)
  package.json          # App manifest

Alloy apps have two JavaScript environments: embeddedjs runs on the watch, while pkjs runs on the connected phone for network and location services.

Hello World

The simplest Alloy app:

console.log("Hello, Pebble!");

Guides

• Advanced Networking - Low-level HTTP and WebSocket clients for advanced networking needs.

• Animations - Create smooth animations using Timeline and easing functions.

• App Messages - Send and receive messages between the watch and the phone.

• Device Info and App Events - Query watch and screen properties, respond to app lifecycle events, and control the backlight in Alloy apps.

• Dictation - Capture speech as text in Alloy apps using the dictation API.

• Getting Started with Alloy - Learn how to create your first Alloy app for Pebble.

• Native Functions (FFI) - Call native C functions directly from JavaScript in your Alloy app using the Foreign Function Interface.

• Networking - Make HTTP requests and use WebSockets via the phone proxy.

• Piu UI Framework - Build declarative user interfaces with the Piu framework.

• Poco Graphics - Low-level graphics rendering with the Poco framework.

• Port (Custom Drawing) - Combine Piu's declarative UI with custom drawing using Port.

• Sensors and Input - Access Pebble sensors and handle button input in Alloy apps.

• Storage - Persist data between app launches using localStorage, key-value storage, or files.

• Vibration - Provide haptic feedback in Alloy apps using the vibration motor.

• Wakeups - Schedule your Alloy app to launch at a future time using wakeups.

• Watchfaces - Build custom watchfaces with Alloy.

Example Apps

The Moddable Pebble Examples repository contains a collection of examples covering all aspects of Alloy development. Here's a categorized overview:

Fundamentals

Storage

Sensors & Input

Piu UI Framework

Piu Watchfaces

Poco Renderer

Communication

Sensor Visualizations (Piu)

Device, Events & Feedback

Native Code

Additional Resources

• Moddable SDK Documentation - Comprehensive documentation for Piu, Poco, and other modules