add example for DFRobot LCD Keypad Shield

examples/LCDKeypadShield_DFRobot/LCDKeypadShield_DFRobot.ino

@@ -0,0 +1,70 @@
+#include <AnalogMultiButton.h>
+
+/*  An example for DFRobot 1602 LCD Keypad Shield
+ *  this shield has 5 keys SELECT, UP, RIGHT, DOWN and LEFT
+ *  product page : https://www.dfrobot.com/product-51.html
+ *  
+ */
+
+// define the pin you want to use
+const int BUTTONS_PIN = A0;
+
+// set how many buttons you have connected
+const int BUTTONS_TOTAL = 5;
+
+// find out what the value of analogRead is when you press each of your buttons and put them in this array
+// you can find this out by putting Serial.println(analogRead(BUTTONS_PIN)); in your loop() and opening the serial monitor to see the values
+// make sure they are in order of smallest to largest
+const int BUTTONS_VALUES[BUTTONS_TOTAL] = {0, 99, 255, 408, 640};
+// you can also define constants for each of your buttons, which makes your code easier to read
+// define these in the same order as the numbers in your BUTTONS_VALUES array, so whichever button has the smallest analogRead() number should come first
+
+const int BUTTON_RIGHT  = 0;
+const int BUTTON_UP     = 1;
+const int BUTTON_DOWN   = 2;
+const int BUTTON_LEFT   = 3;
+const int BUTTON_SELECT = 4;
+
+// make an AnalogMultiButton object, pass in the pin, total and values array
+AnalogMultiButton buttons(BUTTONS_PIN, BUTTONS_TOTAL, BUTTONS_VALUES);
+
+// pass a fourth parameter to set the debounce time in milliseconds
+// this defaults to 20 and can be increased if you're working with particularly bouncy buttons
+
+void setup() {
+  // begin serial so we can see which buttons are being pressed through the serial monitor
+  Serial.begin(9600);
+}
+
+void loop() {
+  // Serial.println(analogRead(BUTTONS_PIN));
+  // update the AnalogMultiButton object every loop
+  buttons.update();
+
+  // check if BUTTON_UP is pressed
+  if(buttons.onPress(BUTTON_UP)){
+     Serial.println("Button Up is pressed");
+  }
+
+  // check if BUTTON_DOWN is pressed
+  if(buttons.onPress(BUTTON_DOWN)){
+    Serial.println("Button Down is pressed");
+  }
+
+  // check if BUTTON_RIGHT is pressed
+  if(buttons.onPress(BUTTON_RIGHT)){
+    Serial.println("Button Right is pressed");
+  }
+
+  //check if BUTTON_LEFT is pressed
+  if(buttons.onPress(BUTTON_LEFT)){
+      Serial.println("Button Left is pressed");
+  }
+
+ //check if BUTTON_SELECT is pressed
+  if(buttons.onPress(BUTTON_SELECT)){
+    Serial.println("Button Select is pressed");
+  }
+
+  delay(10);
+}