Reed switch (magnetic) with ESP32

Supply 3.3 V Bus GPIO

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
1	Output (the part drives it)	D25	To a GPIO; use INPUT_PULLUP. Closes when a magnet is near
2	Ground	GND

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

void setup() {
  Serial.begin(115200);
  pinMode(25, INPUT);  // 1
}

void loop() {
  Serial.println(digitalRead(25));
  delay(100);
}

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