Blink LED

Now that you have verified your environment, let's move on to the "Real" Hello World of embedded systems: Blinking an LED.

In this tutorial, you will learn:

1. How to install external packages.
2. How to wire an LED to the ESP32.
3. How to write code to control GPIO pins.

Step 1: Hardware Setup

Depending on your hardware, choose one of the following setups.

Option A: Using the Onboard LED

Most ESP32 development boards (like the ESP32-DevKitC) have a small blue LED built into the board.

• Pin: Typically GPIO 2.
• Wiring: No external wiring required.

Option B: Using an External LED

If your board does not have an onboard LED, or if you prefer to build a circuit, connect an LED to GPIO 23.

Required Parts:

• 1x LED
• 1x Resistor (220Ω - 1kΩ)
• Breadboard and Jumper wires

Polarity Check

Make sure to connect the longer leg (Anode) of the LED towards the GPIO pin (through the resistor), and the shorter leg (Cathode) to GND.

Step 2: Install GPIO Package

BlueScript keeps the core runtime small. To use hardware features like GPIO, we need to install the driver package.

Run the following command in your project directory:

bscript project install https://github.com/bluescript-lang/pkg-gpio-esp32.git

Step 3: Write Code

Open index.bs and replace its content with the code below.

This program will blink the LED 10 times with a 1-second interval.

Select your Pin

The code below uses GPIO 2 (Onboard LED). If you are using the External LED, change 2 to 23 in the new GPIO(...) line.

index.bs

// Import GPIO class and Enums from the installed package
import { GPIO, PinMode, PinLevel } from "gpio";

// Initialize GPIO 2 as Input/Output mode
// CHANGE THIS TO '23' IF USING EXTERNAL LED
const led = new GPIO(2, PinMode.InputOutput);

console.log("Starting Blink Loop...");

// Blink the LED 10 times
for (let i = 0; i < 10; i++) {
    // Turn LED ON
    led.write(PinLevel.High);
    time.delay(1000); // Wait for 1000ms (1 second)

    // Turn LED OFF
    led.write(PinLevel.Low);
    time.delay(1000);
}

led.close();
console.log("Finished!");

Step 4: Run

Make sure your device is powered on and run:

bscript project run

You should see the LED turn on and off every second!