Tactile button 12 mm with cap with ESP32

Supply 3.3 V Bus GPIO

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
1A	Output (the part drives it)	D25	Legs 1A and 1B are always joined. To a GPIO with INPUT_PULLUP
1B	Not wired to the ESP32	—	Joined to 1A
2A	Ground	GND	Legs 2A and 2B are always joined
2B	Not wired to the ESP32	—	Joined to 2A

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);  // 1A
}

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

Omron B3F tactile switch datasheet, B3F-4000 (12 x 12 mm): terminals 1-2 and 3-4 joined inside

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