JavaScript interpreter for the NumWorks calculator

This apps lets you run a JavaScript script on your NumWorks calculator!

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Install the app

Installing is rather easy:

1. (not yet, see 2) Download the latest javascript.nwa file from the Releases page ;
2. This Release page is not-yet ready, on this project, use this folder instead, and this direct link ;
3. Head to my.numworks.com/apps to send the nwa file on your calculator (on Google Chrome browser). On this page you will be able to also send a default example of a JavaScript file (a tiny test script), and you can edit it yourself later on, on your calculator!

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How to use the app

Just launch the app, and it will read and execute your script javascript.py!

This script should be located in the javascript.py file, that you can create, edit and save from within your NumWorks!.

If you want a demo, use this javascript.py script, that you can install on your NumWorks calculator, directly from their website (from my user space).

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Dependencies

This programs uses the code generated by the Espruino project (espruino_embedded.c, espruino_embedded.h etc), a portable JavaScript interpreter for microcontrolers.

My fork of Espruino

I've started to work on my fork of Espruino, in order to solve this issue: I wanted to give access to NumWorks's EADK library (see eadk.h) to the JavaScript files that are executed in this Espruino JS interpreter. It's a work in progress!

To rebuild the two espruino_embedded.c and espruino_embedded.h files from Espruino's source code, you must run this in its main directory (of my fork, not the main project):

BOARD=EMBED RELEASE=1 V=1 make

Then remove these lines from the espruino_embedded.c file:

typedef unsigned char __u_char;
typedef unsigned short int __u_short;
...
typedef __intmax_t intmax_t;
typedef __uintmax_t uintmax_t;

Copy the files you obtained to the ./src/javascript/ folder on this project (they are included, you shouldn't have to do this, unless you want to help me developping this!).

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Documentation of the Eadk module accessible in JavaScript on the NumWorks

Here is a short documentation for each function that I've ported from their interface in eadk.h to a working version in JavaScript.

I've exposed an Eadk module (see example in JavaScript below, or here), which comes ready with these functions and constants:

Legend:

• ✅ = code written, function tested!
• ✅? = code written, function not yet working!
• ❌ = code written, function unavailable / or code not yet written!!

✅? Eadk predefined colors

Eadk.color_black, Eadk.color_white, Eadk.color_red, Eadk.color_green, Eadk.color_blue are the five predefined colors.

✅ Screen width and height

Eadk.SCREEN_WIDTH and Eadk.SCREEN_HEIGHT are the screen's width and height, respectively.

✅ Controlling the screen's brightness

✅ int Eadk.backlight_brightness()

Returns the screen's brightness, it's a 8 bits integer (uint8_t in C), ranging between 0 (min brightness, screen almost shut down) to 240 (for max brightness).

✅ void Eadk.backlight_set_brightness(int brightness)

Sets the screen's brightness to this value. brightness must be an integer value which fits inside a uint8_t, between 0 and 256.

✅ Accessing the Battery levels

✅ bool Eadk.battery_is_charging()

Indicates whether the battery is charging.

✅ uint8_t Eadk.battery_level()

Returns a 8 bits integer giving the battery level.

✅ float Eadk.battery_voltage()

Returns a floating value of the battery voltage (in Volt, I guess?).

These functions are missing from the hardware! See this issue on NumWorks/epsilon's repository DONE: I just implemented them myself, by SVC calls

❌✅ Display

❌✅ void Eadk.display_draw_string(const char* text, uint16_t x, uint16_t y, bool large_font, uint16_t text_color, uint16_t background_color)

Displays a given text string, at a {x,y} position, in large/small font (large_font?), with the text in text_color and the background in background_color.

Eadk.display_draw_string(text, x, y, large, text_color, background_color);

TODO: it's still a bit buggy! See this issue

✅ void Eadk.display_push_rect_uniform(uint16_t x, uint16_t y, uint16_t width, uint16_t height, uint16_t color)

Fills a rectangle on the display with a uniform color. This can also be used to draw a single pixel by setting width and height to 1.

• x: X coordinate of the top-left corner,
• y: Y coordinate of the top-left corner,
• width: Width of the rectangle,
• height: Height of the rectangle,
• color: Color of the rectangle (e.g., 0xFFFF for white, 0xF800 for red).

For instance:

Eadk.display_push_rect_uniform(0, 0, 10, 20, 0xF800); // Fills a 10x20 red rectangle at (0,0)
Eadk.display_push_rect_uniform(50, 50, 1, 1, 0x07E0); // Draws a single green pixel at (50,50)

✅ bool Eadk.display_wait_for_vblank(void)

Display: wait for vblank? It is not documented in eadk.h so not documented here (we don't really know what it does)

❌ Missing funtions

• Eadk.display_push_rect: is missing.
• Eadk.display_pull_rect: is missing.

✅ Timing

✅ void Eadk.timing_usleep(uint32_t us)

Sleep for us micro-seconds

✅ void Eadk.timing_msleep(uint32_t ms)

Sleep for ms micro-seconds

✅ uint64_t Eadk.timing_millis()

Time since boot of the machine? Not clear. FIXME:

✅ Miscellanious

✅ bool Eadk.usb_is_plugged()

Indicates whether the USB is plugged.

This function is missing from the hardware! See this issue on NumWorks/epsilon's repository DONE: I just implemented it myself, by SVC calls

✅ uint32_t Eadk.random()

Returns an almost truly random number, generated from the hardware RNG (a uint32_t, unsigned 32 bits integer).

How to add new functions to Espruino JavaScript's Eadk module?

To add new functions, edit in my fork of Espruino the files: libs/eadk/jswrap_eadk.c and libs/eadk/jswrap_eadk.h. The functions already present should give a good direction to follow!

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Example of a tiny JavaScript test file

The example below runs now correctly and showcases a few iterations of decrease then increase in brightness, with small pauses between every change:

For a more complete and length example, see src/test.js.

// Save this to `javascript.py` on your NumWorks, and run it with
// the "JS interpreter" NumWorks application!

console.log("Hello world from JavaScript!\n");
console.log("Testing some Eadk functions:\n");
Eadk.timing_msleep(5000);

const brightness = Eadk.backlight_brightness();
console.log("Eadk.backlight_brightness() =", Eadk.backlight_brightness());
Eadk.timing_msleep(2000);

for (let a = 1; a <= 10; a++) {
    for (let b = brightness; b >= 0; b=b-16) {
        Eadk.set_backlight_brightness(b);
        console.log("Eadk.backlight_brightness() =", Eadk.backlight_brightness());
        Eadk.timing_msleep(50);
    }

    for (let b = 0; b <= brightness; b=b+16) {
        Eadk.set_backlight_brightness(b);
        console.log("Eadk.backlight_brightness() =", Eadk.backlight_brightness());
        Eadk.timing_msleep(50);
    }
}

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Build the app

To build this sample app, you will need to install the embedded ARM toolchain and nwlink.

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

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📜 License ?

MIT Licensed (file LICENSE). © Lilian Besson, 2025.