Sample C++ app for Epsilon

This is a sample C++ app to use on a NumWorks calculator.

using namespace EADK;

void eadk_main() {
  Display::pushRectUniform(
    Display::Rect(0, 0, 320, 240),
    Display::Color(0x000000)
  );
  while (1) {
    Keyboard::State kbd = Keyboard::scan();
    if (kbd.keyDown(Keyboard::Key::OK)) {
      spaceship.createRockets();
    }
    if (kbd.keyDown(Keyboard::Key::Up)) {
      spaceship.move(0, -Spaceship::k_step);
    }
    refreshScene();
  }
}

Build the app

You need to install an embedded ARM toolchain and nwlink.

brew install numworks/tap/arm-none-eabi-gcc node # Or equivalent on your OS
npm install -g nwlink
make

Once you target/voord.nwa app is built, you can upload it onto your calculator from NumWorks online uploader.

Run the app (development)

The app is sent over to the calculator using the DFU protocol over USB. The last command has to be executed with the targeted device plugged into the computer.

# Now connect your NumWorks calculator to your computer using the USB cable
make run

Requirements of nwa files

A .nwa file is an ELF file that has the following symbols defined:

eadk_app_name: this is the address of the string representing the name of the app. It will be displayed in the Home of Epsilon. This symbol should be in the .rodata.eadk_app_name section.
eadk_app_api_level: this is a 4-byte integer stating which version of eadk/eadk.s the external app relies on. It is expected to be in the .rodata.eadk_app_api_level section.
eadk_app_icon: this symbol should be defined in the .rodata.eadk_app_icon section and contain the raw NWI data for the icon. Using nwlink you can convert a 55x56 png icon into a NWI format. The NWI format is a raw little-endian RGB565 bitmap that is then LZ4-compressed.
_eadk_main, the entry point of the application.

Optionally, if the external app needs custom binary data, it can reference the eadk_external_data symbol. If so, the NumWorks online uploader will ask for the external data to be provided after dropping the .nwa file. In development, you can provide the --external-data flag to nwlink install-nwa.

Notes

The NumWorks calculator runs Epsilon, a tailor-made calculator operating system. Starting from version 16, Epsilon allows installing custom binary apps. To run this sample app, make sure your calculator is up-to-date by visiting https://my.numworks.com.

Due to the embedded nature of Epsilon, this C++ app is built using -ffreestanding -nostdinc -nostdlib. The interface that an app can use to interact with the OS is essentially a short list of system calls. Feel free to browse the code of Epsilon itself if you want to get an in-depth look.

Please note that any custom app is removed when resetting the calculator.

License

This sample app is distributed under the terms of the BSD License. See LICENSE for details.

Trademarks

NumWorks is a registered trademark.

adriweb / epsilon-sample-app-cpp