Save to Arduine Memory EEPROM

Question

I’m looking to do a Smartphone-controlled lock design. Basically, the user has the option to change the password by Keypad, but I want the new password(String) to be saved in the Internal memory of Arduino (EEPROM), only that I catch it here because it is a string... If you have a solution or any help already counts enough. Follow the code below.

 #include <Keypad.h>
 #include <EEPROM.h>
 #include <LiquidCrystal.h>

 /*-------------------------------KEYPAD---------------------------------------*/
 const byte numRows= 4; //number of rows on the keypad
 const byte numCols= 4; //number of columns on the keypad
 char keypressed;
 char keymap[numRows][numCols]=
       {
       {'1', '2', '3', 'A'},
       {'4', '5', '6', 'B'},
       {'7', '8', '9', 'C'},
       {'*', '0', '#', 'D'}
  };
 byte rowPins[numRows] = {13,12,11,10};//linhas 0 até 3
 byte colPins[numCols] = {9,8,7,6};//Columas 0 até 3 
 Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols);

 /*-------------------------------VARIAVEIS------------------------------------*/

 int rele = 2;
 LiquidCrystal lcd (A0,A1,A2,A3,A4,A5);
 String password="2017"; //SENHA ATUAL
 String tempPassword=""; //VARIAVEL PARA GUARDAR NOVA SENHA
 int doublecheck;    //VERIFICAR 2 VEZES A NOVA SENHA
 boolean armed = false;  //ESTADO ATUAL(ARMADA :TRUE / DESARMADA:false)
 boolean input_pass;   //SENHA (CORRETA:true / ERRADA:false)
 boolean storedPassword = true;
 boolean changedPassword = false;
 boolean checkPassword = false;
 int i = 1; //VARIAVEL PARA CONTROLE DO VETOR
 /*----------------------------------------------------------------------------*/

 void setup(){
   Serial.begin(9600);
   lcd.begin(16, 2);
   pinMode(rele, OUTPUT);
   digitalWrite(rele, LOW);
   lcd.setCursor(0,0);
   lcd.print("PROJETO PI");
   lcd.setCursor(0,1);
   lcd.print("   LOCKPICK  ");
   delay(2000);
   lcd.clear();

 }

 void loop() { //LOOP PRINCIPAL
   unlockTheDoor();
 }
      /********************************FUNCÕES*************************************/

 void unlockTheDoor(){
   lockAgain: //goto label
   tempPassword="";
   i=6;
   digitalWrite(rele, LOW);
   lcd.clear();
   while(!checkPassword){
     lcd.setCursor(0,0);
     lcd.print("ABRA A PORTA  ");
     lcd.setCursor(0,1);
     lcd.print("SENHA>");
     keypressed = myKeypad.getKey();   //Ler as teclas precionadas
     if (keypressed != NO_KEY){    //Accept only numbers and * from keypad
  if (keypressed == '0' || keypressed == '1' || keypressed == '2' || keypressed == '3' ||
  keypressed == '4' || keypressed == '5' || keypressed == '6' || keypressed == '7' ||
  keypressed == '8' || keypressed == '9' ){
         tempPassword += keypressed;
         lcd.setCursor(i,1);
         Serial.println("*");
         lcd.print("*"); 
    i++;  
  }
  else if (keypressed == 'A'){
    //Serial.println("MUDAR SENHA");
    lcd.clear();
      lcd.setCursor(0, 0);
     lcd.print("MUDAR SENHA"); 
     delay(1000);
    changePassword();
    goto lockAgain;
  }
  else if (keypressed=='#'){
    lcd.clear();
    break;
  }
  else if (keypressed == '*'){ 
    //CONFIRIR SENHA
    if (password==tempPassword){//SE FOR CORRETA...
      lcd.clear();      
      lcd.setCursor(0,0);
      lcd.print("SENHA CORRETA");
      lcd.setCursor(0,1);
      lcd.print("PORTA DESBLOQUEADA");
      Serial.println("opened");
      digitalWrite(rele, HIGH);//CODIGO DA PORTA AQUI
      delay(8000);
      goto lockAgain;
    }
    else{           //CASO FALSO, TENTE NOVAMENTE
      tempPassword="";
      Serial.println("SENHA INCORRETA");
      delay(5000);
      goto lockAgain;
    }
  }
}
   }
 }     

 //Change current password
 void changePassword(){
   retry: //label for goto
   tempPassword="";
   lcd.clear();
   i=1;
   while(!changedPassword){        //AGUARDANDO PELA SENHA
keypressed = myKeypad.getKey();
lcd.setCursor(0,0);
lcd.print("SENHA ATUAL");
lcd.setCursor(0,1);
lcd.print(">");
if (keypressed != NO_KEY){
  if (keypressed == '0' || keypressed == '1' || keypressed == '2' || keypressed == '3' ||
  keypressed == '4' || keypressed == '5' || keypressed == '6' || keypressed == '7' ||
  keypressed == '8' || keypressed == '9' ){
    tempPassword += keypressed;
    lcd.setCursor(i,1);
    lcd.print("*");
    i++;     
  }
  else if (keypressed=='#'){
    break;
  }
  else if (keypressed == '*'){
    i=1;
    if (password==tempPassword){
      lcd.clear();
      lcd.print("Senha Confirmada");
      delay(1000);
      lcd.clear();
      storedPassword=false;
      newPassword();          //Se a senha estiver certa, chama a função newPassword
      break;
    }
    else{               //tente denovo
      tempPassword="";
      goto retry;
         }
       }
     }
   }
 }
 String firstpass;
 //DENIFIR NOVA SENHA
 void newPassword(){
   tempPassword="";
   changedPassword=false;
   lcd.clear();
   i=1;
   while(!storedPassword){
     keypressed = myKeypad.getKey();   //LER AS TECLAS
     if (doublecheck==0){
       lcd.setCursor(0,0);
       lcd.print("INSIRA NOVA SENHA");
  lcd.setCursor(0,1);
  lcd.print(">");
}
else{
  lcd.setCursor(0,0);
  lcd.print("CONFIRME SUA NOVA SENHA...");
  lcd.setCursor(0,1);
  lcd.print(">");
}
if (keypressed != NO_KEY){
  if (keypressed == '0' || keypressed == '1' || keypressed == '2' || keypressed == '3' ||
  keypressed == '4' || keypressed == '5' || keypressed == '6' || keypressed == '7' ||
  keypressed == '8' || keypressed == '9' ){
    tempPassword += keypressed;
    lcd.setCursor(i,1);
    lcd.print("*");
    i++;
  }
  else if (keypressed=='#'){
    break;
  }
  else if (keypressed == '*'){
    if (doublecheck == 0){
      firstpass=tempPassword;
      doublecheck=1;
      newPassword();
    }
    if (doublecheck==1){
      doublecheck=0;
      if (firstpass==tempPassword){
        i=1;
        firstpass="";
        password = tempPassword;
        tempPassword="";//APAGAR SENHA TEMP
        lcd.setCursor(0,0);
        lcd.print("SENHA TROCADA");
        lcd.setCursor(0,1);
        lcd.print("----------------");
          storedPassword=true;
          delay(2000);
          lcd.clear();
          break;
      }
      else{
        firstpass="";
        newPassword();
           }
         }
      } 
     }
   }
 }

Answer 1

The question has a while, but I will answer to help anyone who finds this topic.

Since the amount of data is less than 1kb (memory limit to be manipulated on the atmega328 chip), you can use the bibilioteca:

 #include <EEPROM.h>

With the methods:

 EEPROM.write()
 EEPROM.read() 

Read the documentation on: https://playground.arduino.cc/Code/EEPROMLoadAndSaveSettings

But be aware that the writing and reading is done in byte and not in string.

I found this code on: https://forum.arduino.cc/index.php?topic=430656.0

I haven’t tried it, but the forum says it works.

void save_string_to_eeprom(char *stringIn){

  Serial.print("stringIn length: ");
  Serial.print(strlen(stringIn));
  Serial.println();

    for(int i = 0; i < strlen(stringIn); i++){

      EEPROM.write(i, stringIn[i]);

  }

}

void read_string_from_eeprom(char *bufferIn){

  Serial.print("bufferIn sizeof: ");
  Serial.print(sizeof(bufferIn));
  Serial.println();

    for(int i = 0; i < eeprom_size; i++){

        bufferIn[i] = EEPROM.read(i);

    }

}