Update

Processing/Sketches/Sketch_06_1_1_ADC/ADCDevice.pde

@@ -10,7 +10,8 @@ class ADCDevice {
   public int cmd = 0;
   public I2C i2c;
   public ADCDevice() {
-    i2c = new I2C(I2C.list()[0]);
+    //Note that if you are running on a version 1 Raspberry Pi, you need to change the subscript index to 0.
+    i2c = new I2C(I2C.list()[1]);
   }
 
   public boolean detectI2C(int addr) {

Processing/Sketches/Sketch_07_1_1_SoftLight/ADCDevice.pde

@@ -10,7 +10,8 @@ class ADCDevice {
   public int cmd = 0;
   public I2C i2c;
   public ADCDevice() {
-    i2c = new I2C(I2C.list()[0]);
+    //Note that if you are running on a version 1 Raspberry Pi, you need to change the subscript index to 0.
+    i2c = new I2C(I2C.list()[1]);
   }
 
   public boolean detectI2C(int addr) {

Processing/Sketches/Sketch_08_1_1_Thermometer/ADCDevice.pde

@@ -10,7 +10,8 @@ class ADCDevice {
   public int cmd = 0;
   public I2C i2c;
   public ADCDevice() {
-    i2c = new I2C(I2C.list()[0]);
+    //Note that if you are running on a version 1 Raspberry Pi, you need to change the subscript index to 0.
+    i2c = new I2C(I2C.list()[1]);
   }
 
   public boolean detectI2C(int addr) {

Processing/Sketches/Sketch_14_1_1_Joystick/ADCDevice.pde

@@ -10,7 +10,8 @@ class ADCDevice {
   public int cmd = 0;
   public I2C i2c;
   public ADCDevice() {
-    i2c = new I2C(I2C.list()[0]);
+    //Note that if you are running on a version 1 Raspberry Pi, you need to change the subscript index to 0.
+    i2c = new I2C(I2C.list()[1]);
   }
 
   public boolean detectI2C(int addr) {

Processing/Sketches/Sketch_14_1_1_Joystick/SingleKey.pde

@@ -0,0 +1,101 @@
+/*
+ ******************************************************************************
+ * class  SingleKey
+ * Author  Freenove (http://www.freenove.com)
+ * Date    2016/08/27
+ ******************************************************************************
+ * Brief
+ *   This class is used to get a single button key value (GPIO numbering)
+ ******************************************************************************
+ * Copyright
+ *   Copyright © Freenove (http://www.freenove.com)
+ * License
+ *   Creative Commons Attribution ShareAlike 3.0 
+ *   (http://creativecommons.org/licenses/by-sa/3.0/legalcode)
+ ******************************************************************************
+ */
+int keyValue = -1;
+class SingleKey {
+  final int IDLE = 0, 
+    PRESSED = 1, 
+    HOLD = 2, 
+    RELEASED = 3;
+  int btnState = IDLE;
+  boolean isPressed = false;
+  boolean isHold = false;
+  long holdTimer = 0;
+  final int holdTime = 100;
+  boolean changeState = false;
+  int lastButtonIOState = GPIO.HIGH;
+  int buttonIOState=GPIO.HIGH;
+  int nowButtonState;
+  boolean buttonChanged = false;
+  int lastChangeTime;
+  int decounceTime = 20;
+  int pin;
+  public SingleKey(int Pin) {
+    pin = Pin;
+    GPIO.pinMode(pin, GPIO.INPUT);
+  }
+
+  void keyScan() {
+    nowButtonState =GPIO.digitalRead(pin);
+    if (nowButtonState != lastButtonIOState) {
+      lastChangeTime = millis();
+    }
+    if (millis() - lastChangeTime > decounceTime) {
+      if (buttonIOState != nowButtonState) {
+        buttonIOState = nowButtonState;
+        changeState = true;
+        if (buttonIOState == GPIO.LOW) {
+          //btnState = PRESSED;
+          //keyValue = pin;
+          //println("Key is Pressed !! ");
+        } else if (buttonIOState == GPIO.HIGH) {
+          //println("Key is Released !! ");
+        }
+      }
+    }
+    switch(btnState) {
+    case IDLE:
+      if (changeState) {
+        changeState = false;
+        btnState = PRESSED;
+        holdTimer = millis();
+        keyValue = pin;
+        isPressed = true;
+      }
+      break;
+    case PRESSED:
+      if (millis() - holdTimer > holdTime) {
+        btnState = HOLD;
+        keyValue = pin;
+        isPressed = true;
+        isHold = true;
+      } else if (changeState) {
+        changeState = false;
+        btnState = RELEASED;
+      } else {
+        keyValue = -1;
+        isPressed = false;
+      }
+      break;
+    case HOLD:
+      keyValue = pin;
+      isPressed = true;
+      isHold = true;
+      if (changeState) {
+        changeState = false;
+        btnState = RELEASED;
+      }
+      break;
+    case RELEASED:
+      keyValue = -1;
+      isPressed = false;
+      isHold = false;
+      btnState = IDLE;
+      break;
+    }
+    lastButtonIOState = nowButtonState;
+  }
+}

Processing/Sketches/Sketch_14_1_1_Joystick/Sketch_14_1_1_Joystick.pde

@@ -5,10 +5,12 @@
  * modification: 2020/03/11
  *****************************************************/
 import processing.io.*;
-//Create a object of class ADCDevice
+//Create an object of class ADCDevice
 ADCDevice adc = new ADCDevice();
-int cx, cy, cd, cr;    //define the center point,side length & half.
+int cx, cy, cd, cr;    //define the center point, side length & half.
 
+int buttonPin = 18;
+SingleKey skey = new SingleKey(buttonPin);
 void setup() {
   size(640, 360);
   if (adc.detectI2C(0x48)) {
@@ -28,7 +30,13 @@ void draw() {
   int x=0, y=0, z=0;
   x = adc.analogRead(0);  //read the ADC of joystick
   y = adc.analogRead(1);  //
-  z = adc.analogRead(2);
+  //z = adc.analogRead(2);
+  skey.keyScan();    //key scan
+  if (skey.isPressed) {  //key is pressed
+    z=0;
+  } else {
+    z = 255;
+  }
   background(102);
   titleAndSiteInfo();
   fill(0);