Unlocking WebScreen's Potential with Elk JavaScript Engine
In the rapidly evolving world of technology and the Internet of Things (IoT), personalization and adaptability are key. At HW Lab, we're excited to introduce how integrating the Elk JavaScript engine into WebScreen empowers users to create their own applications using JavaScript, all stored conveniently on a micro SD card.
In this blog post, we'll delve into what WebScreen is, how Elk enhances its capabilities, and explore potential use cases that this powerful combination unlocks.
1. Introducing WebScreen
WebScreen is your new sidekick that keeps you connected without breaking your focus. Whether you're deep into gaming, streaming, or working, WebScreen brings essential notifications, reminders, and engaging visuals right where you need them. It's a sleek secondary display that seamlessly fits into your setup, enhancing both productivity and enjoyment.
Key Features of WebScreen:
Notifications: Stay updated with important alerts without disrupting your current activity.
Reminders: Sync with your calendars and apps to manage your day effectively.
Prompter: Use as a handy teleprompter during streams or presentations.
Photo Display: Showcase your favorite images or artwork.
Cool Visuals: Add flair to your setup with animations and videos.
Customizable: Program WebScreen with your own apps to suit your needs.
WebScreen's design is sleek and seamless, mounting like a webcam and allowing for easy adjustments. Its AMOLED display delivers crisp, vibrant visuals, making it both a functional and stylish addition to any workspace or gaming setup.
2. Why Elk JavaScript Engine?
Embedded systems like WebScreen often have limited processing power and memory. Traditional JavaScript engines are too resource-intensive for such environments. Elk is a minimal, embeddable JavaScript engine designed specifically for microcontrollers and embedded systems.
Advantages of Elk:
Lightweight Footprint: Requires minimal memory, perfect for devices like the ESP32.
Simplicity: Supports essential JavaScript features needed for embedded applications.
Easy Integration: Designed to embed seamlessly into existing projects.
By integrating Elk, we enable users to write and execute JavaScript code directly on WebScreen, opening up a world of customization and functionality.
3. Integrating Elk into WebScreen
The integration process involves embedding the Elk engine into the WebScreen firmware and exposing native functions to interact with the hardware components.
Setting Up Elk
We added the Elk source files to our project and initialized the engine with a dedicated memory buffer:
// Include the Elk header
#include "elk.h"
static struct js *js;
void setup() {
// Initialize Elk with a memory buffer
static uint8_t elk_memory[8192]; // Adjust size as needed
js = js_create(elk_memory, sizeof(elk_memory));
if (js == NULL) {
Serial.println("Failed to initialize Elk");
return;
}
// Register native functions
register_js_functions();
}
Exposing Native Functions
We created native functions to allow JavaScript code to interact with WebScreen's hardware:
Wi-Fi Connectivity:
static jsval_t js_wifi_connect(struct js *js, jsval_t *args, int nargs) {
// Implementation of Wi-Fi connection
}
SD Card Operations:
static jsval_t js_sd_read_file(struct js *js, jsval_t *args, int nargs) {
// Implementation of SD card file reading
}
GPIO Control:
static jsval_t js_gpio_write(struct js *js, jsval_t *args, int nargs) {
// Implementation of GPIO write
}
Registering Functions with Elk
void register_js_functions() {
jsval_t global = js_glob(js);
// Register global functions
js_set(js, global, "print", js_mkfun(js_print));
js_set(js, global, "wifi_connect", js_mkfun(js_wifi_connect));
js_set(js, global, "sd_read_file", js_mkfun(js_sd_read_file));
js_set(js, global, "gpio_write", js_mkfun(js_gpio_write));
}
4. Empowering User-Created Applications
With Elk integrated into WebScreen, users can now create their own JavaScript applications to:
Control Hardware Components: Access GPIO pins, read sensors, control LEDs, and more.
Manage Connectivity: Connect to Wi-Fi networks, send and receive data.
Process Data: Perform computations, handle data from sensors, and manipulate information.
This flexibility transforms WebScreen from a passive display into an interactive platform that can be tailored to individual needs.
5. Storing and Executing Scripts from Micro SD Card
To make customization even more accessible, WebScreen allows users to store their JavaScript scripts on a micro SD card.
Loading Scripts
bool load_and_execute_js_script(const char* path) {
Serial.printf("Loading JavaScript script from: %s\n", path);
File file = SD_MMC.open(path);
if (!file) {
Serial.println("Failed to open JavaScript script file");
return false;
}
// Read the entire file into a string
String jsScript = file.readString();
file.close();
// Execute the JavaScript script
jsval_t res = js_eval(js, jsScript.c_str(), jsScript.length());
if (js_type(res) == JS_ERR) {
const char *error = js_str(js, res);
Serial.printf("Error executing script: %s\n", error);
return false;
}
Serial.println("JavaScript script executed successfully");
return true;
}
Benefits of Using Micro SD Card
Ease of Update: Modify or replace scripts without needing to reflash the firmware.
Storage Capacity: Plenty of space for multiple scripts and resources.
Portability: Easily transfer scripts between devices.
6. Potential Use Cases
The combination of WebScreen and Elk unlocks numerous possibilities:
Custom Interfaces
Home Automation Dashboards: Control smart devices and monitor home systems.
Industrial Control Panels: Interface with machinery or sensors in an industrial setting.
Educational Tools: Develop interactive learning modules or demonstrations.
Data Logging and Processing
Sensor Data Collection: Read from environmental sensors and log data for analysis.
Real-Time Monitoring: Display live data from various sources for immediate insight.
IoT Connectivity
Network Communication: Send and receive data over the network, interact with APIs.
Cloud Integration: Connect to cloud services for extended functionality.
Interactive Projects
Art Installations: Create dynamic visual displays or interactive exhibits.
Games and Entertainment: Develop simple games or playful applications.
7. Getting Started with WebScreen and Elk
Prerequisites
WebScreen Device with Micro SD Card Support
Micro SD Card
Arduino IDE Installed
Step 1: Prepare the SD Card
Format the SD card to FAT32.
Create a JavaScript file named script.js.
Step 2: Write Your JavaScript Application
Here's a sample script.js that connects to Wi-Fi and blinks an LED:
"use strict";
// Wi-Fi credentials
let ssid = "YourSSID";
let password = "YourPassword";
// Connect to Wi-Fi
print("Connecting to Wi-Fi...");
let connected = wifi_connect(ssid, password);
if (connected) {
print("Connected to Wi-Fi");
let ip = wifi_get_ip();
print("IP Address:");
print(ip);
} else {
print("Failed to connect to Wi-Fi");
}
// Blink an LED connected to GPIO 2
let ledPin = 2;
gpio.mode(ledPin, 1); // Set pin as OUTPUT
for (let i = 0; i < 5; i = i + 1) {
gpio.write(ledPin, 1); // Turn LED on
delay(500);
gpio.write(ledPin, 0); // Turn LED off
delay(500);
}
print("Finished blinking LED");Step 3: Load the Script onto the SD Card
Save script.js to the root directory of the SD card.
Insert the SD card into the WebScreen device.
Step 4: Power Up and Monitor Output
Power on the WebScreen device.
Open the Serial Monitor in the Arduino IDE at 115200 baud rate.
Observe the output to verify that your script runs successfully.
8. Conclusion
By integrating the Elk JavaScript engine into WebScreen, we've transformed it into a versatile platform that empowers users to create customized applications tailored to their specific needs. Whether you're a developer looking to innovate or a hobbyist exploring new possibilities, WebScreen combined with Elk provides the tools to bring your ideas to life.
Join us in embracing this new level of personalization and let's see what amazing creations you come up with!
