This is a sample C++ app to use on a NumWorks calculator.
This is a repository for building Omega/Upsilon external applications for Epsilon 16's external applications.
You just need to copy the source code into the src/app folder of the repository and run make clean && make run to build and run the application.
To change the application name, change the eadk_app_name variable in src/main.cpp.
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();
}
}You need to install an embedded ARM toolchain and a couple Python modules. The last command has to be executed with the targeted device plugged to the computer.
brew install numworks/tap/arm-none-eabi-gcc # Or equivalent on your OS
pip3 install lz4 pypng
make clean && make runThe app is sent over to the calculator using the DFU protocol over USB.
brew install dfu-util # Or equivalent on your OS
# Now connect your NumWorks calculator to your computer using the USB cable
make runThe 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. Note that at the moment Epsilon 16 is in beta, so you'll need to register as a beta tester.
Epsilon expects apps to follow a certain layout in memory. Namely, they should start with the following header:
| Offset | Size | Value | Description |
|---|---|---|---|
| 0x00 | 0x04 | 0xDEC0BEBA | Magic start-of-header marker |
| 0x04 | 0x04 | 0x00000000 | API Level |
| 0x08 | 0x04 | - | Offset from start of the app to a NULL-terminated NFKD UTF-8 string containing the app name |
| 0x0C | 0x04 | - | Size of the icon data |
| 0x10 | 0x04 | - | Offset from start of the app to the actual icon data. This data should be the result of LZ4-compressing a sequence of 55x56 RGB565 pixels |
| 0x14 | 0x04 | - | Offset from start of the app to the entry point. |
| 0x18 | 0x04 | - | Size of the entire app |
| 0x22 | 0x04 | 0xDEC0BEBA | Magic end-of-header marker |
Generating the appropriate header is taken care of by a linker script when you run make build.
The information about where to link in flash and in RAM are dynamically extracted from headers provided by the calculator. The RAM is mapped from 0x2000 0000 and starts with the following header:
| Offset | Size | Value | Description |
|---|---|---|---|
| 0x00 | 0x04 | 0xEFEEDBBA | Magic start-of-header marker |
| 0x04 | 0x04 | - | Pointer to kernel header |
| 0x08 | 0x04 | - | Pointer to userland header |
| 0x0C | 0x04 | 0xEFEEDBBA | Magic end-of-header marker |
The userland header gives the following information useful to link the external application:
| Offset | Size | Value | Description |
|---|---|---|---|
| 0x00 | 0x04 | 0xDEC0EDFE | Magic start-of-header marker |
| 0x04 | 0x04 | - | Version of epsilon that should be matched by kernel |
| 0x08 | 0x04 | - | Storage address in RAM |
| 0x0C | 0x04 | - | Storage size |
| 0x10 | 0x04 | - | External applications start address in flash |
| 0x14 | 0x04 | - | External applications end address in flash |
| 0x18 | 0x04 | - | External applications start address in RAM |
| 0x1C | 0x04 | - | External applications end address in RAM |
| 0x20 | 0x04 | 0xDEC0EDFE | Magic end-of-header marker |
This dynamic linking process is taken care of by get_device_information.py script.
Once the corresponding binary is built on your computer, you will need to install it in your calculator's Flash memory. The included run.py script will take care of this for you when you call make run.
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.
This sample app is distributed under the terms of the BSD License. See LICENSE for details.
NumWorks is a registered trademark.