The online Bangle.js emulator, accessible through the Espruino IDE, is pretty neat and useful for app development, but it doesn't help with firmware development—and some people might prefer not to have to use a browser as a development environment in any case. This repository contains a standalone emulator that can be used for developing Bangle.js 2 apps or firmware without a physical device. (Even if you have a physical device, using the emulator will likely be faster and more convenient, unless of course you are developing something that relies on the real hardware.)
Features:
- TUI showing screen and console output
- touchscreen and button input
- device console served over TCP
- config file for conveniently specifying initial emulator state
- reset/interrupt on button hold
Current non-features:
- sensor inputs
- screen lock/backlight tracking
You'll need a version of the Espruino firmware compiled to WebAssembly. The Espruino upstream currently does not support creating the necessary WebAssembly build; see the wasm branch of my fork to get a version with the relevant changes. You can download a precompiled version from the GitHub Actions there or clone the repository and perform the build yourself (install Emscripten and run RELEASE=1 BOARD=EMSCRIPTEN2 make; the output will be in bin/emulator_banglejs2.wasm).
You can also use a TOML config file to specify the state of the emulated watch on startup (by default, the watch will start with nothing in storage, like in the Espruino IDE). The file sample-config.toml in this repository demonstrates a basic config and some commented examples.
As for the emulator itself, binaries are available at the GitHub Actions for this repository (for Linux, macOS, and Windows), or you can build it yourself by cloning this repository and setting up a recent Rust toolchain. To start the emulator, run the first command below if you downloaded a binary or the second if you are building it yourself:
banglejs-emu [-c <config file>] <firmware file>
cargo run --release [-c <config file>] <firmware file>The screen and console output will be displayed in the terminal; you can click on the screen to provide touch inputs, including drags and swipes, and press Enter to press the button. The emulator also exposes the emulated watch's console over TCP (listening on localhost:37026 by default; use -b to change). Running rlwrap nc localhost 37026 or socat readline tcp:localhost:37026 (see rlwrap, netcat, socat) will connect to the console with a somewhat shell-like experience.
Press q or Escape to quit.
You can have apps (including widgets and clocks) installed on startup by using the config file to place the required files onto the watch's storage. The sample config file contains some examples of how to do this.
The most important file is the JavaScript code itself. The standard, as defined by the App Loader, is for this to be called <appname>.app.js (for apps and clocks) or <appname>.wid.js (for widgets), though Espruino itself doesn't really care. This is the same thing that would normally be placed on the watch by the App Loader, apart from minification, so you can specify the contents by providing a path to a file in a BangleApps clone or wherever else you might be working on your code. You can start the app by using the load(<file>) function in Espruino.
If you're using the standard launcher (which will be present after a factory reset), you'll also need a file called <appname>.info for the app to show up in the launcher, containing a JSON object describing the metadata for the app. Normally, this file is generated dynamically by the App Loader and doesn't exist otherwise, so you'll probably want to specify the contents directly in the config file.
Apps may also make use of other files, such as images or settings files. The details will vary from app to app; each app's metadata.json file describes what files it uses.
Licensed under either of Apache License, Version 2.0 or MIT license at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.