ESP32 GPIO34

Everything you need to use this pin correctly: status, alternate functions, boot-time cautions and working code.

Practical notes

Input-only pin carrying ADC1_CH6. No internal pull-up/pull-down and no output driver — driving an LED or relay needs external hardware. Safe for ADC sampling since ADC1 is unaffected by Wi-Fi.

Sample code

// Arduino
const int PIN = 34;

void setup() {
  Serial.begin(115200);
  analogReadResolution(12);
  // set attenuation before measuring higher voltages
  analogSetAttenuation(ADC_11db);
}

void loop() {
  int raw = analogRead(PIN);
  Serial.println(raw);
  delay(1000);
}

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