XL LED

What it is

One LED, one resistor, and a header. The LED is blue with a 10 mm lens. The resistor beside it is 150 Ω, and it is the reason the block exists: a bare LED wired straight to a pin draws whatever current the pin can give, and eventually takes the pin with it.

It is active high. Set SIGNAL HIGH and it lights, LOW and it goes out. The front of the board says ACTIVE HIGH and the back says GLOWS WHEN HIGH, so there is no doubt which way round it works.

There is no supply pin

Most blocks have a VCC pin. This one doesn't: the pin you drive is the LED's power. That has one consequence worth knowing before you plug it in. The LED takes about 3.0 V, and only what is left over drives current through the resistor, so it is much brighter from a 5 V board than from a 3.3 V one:

Both are within what the pin may supply, and both are plainly lit. The currents are bench measurements of one board; the LED has no datasheet.

Which pin is which

LED side up, header at the bottom, reading left to right:

The back prints TK01 XL LED and GLOWS WHEN HIGH instead of pin names. Turned over, the square pad is on the right, and it is still GND.

Wiring, in two lines

1. GND to your board's GND.
2. SIGNAL to a digital pin: D9 on an Uno, GPIO 4 on an ESP32 or ESP32-S3, GP15 on a Pico. Those are all PWM pins, so the same wiring also dims it.

Leave both NC pins unconnected. No resistor to add, no library to install.

Example

// The GPIO number SIGNAL is wired to. Uno: 9. ESP32, ESP32-S3: 4. Pico: 15.
const int LED_PIN = 4;

void setup() {
  pinMode(LED_PIN, OUTPUT);     // without this, HIGH is only a weak pull-up
}

void loop() {
  digitalWrite(LED_PIN, HIGH);  // the pin supplies the LED's current
  delay(500);
  digitalWrite(LED_PIN, LOW);
  delay(500);
}

from machine import Pin
import time

# The GPIO number SIGNAL is wired to. ESP32, ESP32-S3: 4. Pico: 15.
led = Pin(4, Pin.OUT)

while True:
    led.on()      # HIGH: the pin supplies the LED's current
    time.sleep(0.5)
    led.off()
    time.sleep(0.5)

Where to start

The handbook below is nine short articles, each with a working figure. The first blink is the whole build in two wires and five lines.

If you only read one, read what the resistor is for. It is the reason the block exists, and the reason not to wire a bare LED to a pin.

And if it looks dim on your ESP32, why it is dimmer on 3.3 V works out why that is normal and what the real options are.