Read-Sensor-Resistances/espVoltmeter/espVoltmeter.ino

// manually define all the An ports on ESP32 board
#define A0 (36)
#define A1 (39)
#define A2 (34)
#define A3 (35)
#define A4 (32)
#define A5 (33)

// define the divident of sizeof()'s return value, to the correct length of our list
#define SIZE_DIV 4  // for esp32, the resolution is doubled than the usual arduino board, so we double the factor, too
#define WAIT_TIME 1000UL
int pins[] = { A0, A1, A2, A3, A4, A5 };
int i, j;
unsigned long currTime;  // non-blocking time tracker

void setup() {
  Serial.begin(19200);
  currTime = millis();
  Serial.println();
}

void loop() {
  if (millis() - currTime >= WAIT_TIME) {  // non-blocking time delay
    Serial.print("[");
    for (i = 0; i < sizeof(pins) / SIZE_DIV; i++) {
      Serial.print(analogReadMilliVolts(pins[i]), DEC);
      if (i != sizeof(pins) / SIZE_DIV - 1) {  // fence-post the list print
        Serial.print(", ");
      }
    }
    Serial.println("]");
    currTime = millis();
  }
}