LED with 220 Ω resistor with ESP32

Supply 3.3 V Bus GPIO

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
A	Input (the ESP32 drives it)	D25	Anode (long leg), through the resistor to a GPIO
K	Ground	GND	Cathode (short leg, flat side)

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

The long leg (anode) goes to the pin, the short leg to GND, always through a resistor (220 Ω to 1 kΩ). (Arduino examples, Blink: circuit)

void setup() { pinMode(25, OUTPUT); }  // A

void loop() {
  digitalWrite(25, HIGH);
  delay(500);
  digitalWrite(25, LOW);
  delay(500);
}

Generic 5 mm LED, Forward voltage about 2 V (red); 220 Ω at 3.3 V gives about 6 mA

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.