アルディーノで膜スイッチを使ったよ!

 i = customKey- '0';

でCHAR型のデータを数値に変換してLEDの点灯時間に利用しています。

 

#include <Keypad.h>
#include <string.h>
const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns
//define the cymbols on the buttons of the keypads
char hexaKeys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; //connect to the column pinouts of the keypad

//initialize an instance of class NewKeypad
Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS); 

void setup(){
  Serial.begin(9600);
  pinMode(11,OUTPUT);
  digitalWrite(11,LOW);
}
  
void loop(){
  int i;
  char customKey = customKeypad.getKey();
  
  if (customKey){
    Serial.println(customKey);
   i = customKey- '0';
    if(i >= 0 && i <= 9){
      digitalWrite(11,HIGH);
      Serial.println(i*1000); 
      delay(i * 1000);
      digitalWrite(11,LOW);

      }
  }
 
}