Measuring capacitance on arduino due

hello, I want to get capacitance value using the code below.
but I have to use arduino due, and I don't know arduino due's stray capacitance.

what is arduino due's stray capacitance value???
I already set analogReadResolution to 12.

const int OUT_PIN = A2;
const int IN_PIN = A0;

//Capacitance between IN_PIN and Ground
//Stray capacitance is always present. Extra capacitance can be added to
//allow higher capacitance to be measured.
const float IN_STRAY_CAP_TO_GND = 24.48; //initially this was 30.00
const float IN_EXTRA_CAP_TO_GND = 0.0;
const int MAX_ADC_VALUE = 4095;

void setup()
  pinMode(OUT_PIN, OUTPUT);
  //digitalWrite(OUT_PIN, LOW);  //This is the default state for outputs
  pinMode(IN_PIN, OUTPUT);
  //digitalWrite(IN_PIN, LOW);


void loop()
  //Capacitor under test between OUT_PIN and IN_PIN
  //Rising high edge on OUT_PIN
  pinMode(IN_PIN, INPUT);
  digitalWrite(OUT_PIN, HIGH);
  int val = analogRead(IN_PIN);

  //Clear everything for next measurement
  digitalWrite(OUT_PIN, LOW);
  pinMode(IN_PIN, OUTPUT);

  //Calculate and print result

  float capacitance = (float)val * IN_CAP_TO_GND / (float)(MAX_ADC_VALUE - val);

  Serial.print(F("Capacitance Value = "));
  Serial.print(capacitance, 3);
  Serial.print(F(" pF ("));
  Serial.println(F(") "));

  while (millis() % 500 != 0)

You have to measure the entire stray capacitance of your setup.

Does the Due have Schmitt Trigger inputs as required for this project?

Yes it does

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