CD74HC4067 16-channel analog multiplexer with ESP32

Supply 3.3-5 V Bus ANALOG

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
SIG	Analog output	D34	Common signal: to an ADC1 pin (GPIO 32 to 39)
S3	Input (the ESP32 drives it)	D25	Channel select bit 3
S2	Input (the ESP32 drives it)	D26	Channel select bit 2
S1	Input (the ESP32 drives it)	D27	Channel select bit 1
S0	Input (the ESP32 drives it)	D32	Channel select bit 0
EN	Not wired to the ESP32	—	Enable, active LOW. Tie to GND
VCC	Power	3V3	Use 3.3 V so no channel goes above 3.3 V
GND	Ground	GND
C0	Not wired to the ESP32	—	Channel 0: to a sensor or button, not to the ESP32
C1	Not wired to the ESP32	—
C2	Not wired to the ESP32	—
C3	Not wired to the ESP32	—
C4	Not wired to the ESP32	—
C5	Not wired to the ESP32	—
C6	Not wired to the ESP32	—
C7	Not wired to the ESP32	—
C8	Not wired to the ESP32	—
C9	Not wired to the ESP32	—
C10	Not wired to the ESP32	—
C11	Not wired to the ESP32	—
C12	Not wired to the ESP32	—
C13	Not wired to the ESP32	—
C14	Not wired to the ESP32	—
C15	Not wired to the ESP32	—

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); }

void loop() {
  int mv = analogReadMilliVolts(34);  // SIG on GPIO 34
  Serial.println(mv);
  delay(200);
}

Texas Instruments CD74HC4067 datasheet, Truth table S0 to S3 and E; supply 2 to 6 V
SparkFun Analog/Digital MUX breakout (BOB-09056), Header SIG, S3, S2, S1, S0, EN, VCC, GND and C0 to C15

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