Arduino Nano misreads the 4x4 hard keypad

[soviet_otaku]

Hi people, I am doing a project wich in a part of it involves the use of a matrix keypad 4x4 and an arduino nano, according the the input from the keypad (a password) the arduino nano must send a digital signal through the pin d13 for 3 seconds.

I can see the input i am writing at a lcd screen.

The problem is that the characters received by the nano does not match with the ones I press in the hard keyboard. For example if I press the "2" icon then the arduino marks it as "4". It only recognizes correctly the "1", "5","9" and "D" .

The code worked well with arduino uno.
It also worked using a different keyboard model.

This is the model it worked with

This is the model I want to work with

I am sharing the code too:

#include <Wire.h>
#include <Keypad.h>
#include <LiquidCrystal_PCF8574.h>

// Configura la dirección I2C y el tamaño del LCD
LiquidCrystal_PCF8574 lcd(0x27); // Cambia 0x27 por la dirección de tu pantalla

// Configuración del teclado matricial 4x4
const byte filas = 4; // Número de filas
const byte columnas = 4; // Número de columnas

// Mapeo de teclas (ajusta según tu teclado)
char teclas[filas][columnas] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

// Pines conectados al teclado (ajusta según tu conexión)
byte pinesFilas[filas] = {9, 8, 7, 6};  // Pines digitales del Arduino Nano para las filas
byte pinesColumnas[columnas] = {5, 4, 3, 2}; // Pines digitales del Arduino Nano para las columnas

Keypad teclado = Keypad(makeKeymap(teclas), pinesFilas, pinesColumnas, filas, columnas);

// Configuración de la contraseña
String contrasena = "2016"; // Contraseña correcta
String entrada = "";        // Almacena la entrada del usuario
String entradaesp32 ="";   // Almacena informacion serial desde ESP32

// Configuración de la salida digital
const int salida = 13; // Pin digital del Arduino Nano para la salida (ajusta según tu preferencia)
const unsigned long tiempoActivo = 3000; // Tiempo en milisegundos (3 segundos)

void setup() {
  // Inicia la comunicación serial con el ESP32
  Serial.begin(9600); // Comunicación a través de los pines RX y TX por defecto

  // Configuración de la salida digital
  pinMode(salida, OUTPUT);
  digitalWrite(salida, LOW);

  // Inicializa el LCD
  Wire.begin();     // Inicia la comunicación I2C
  lcd.begin(16, 2);  // Inicializa el LCD con 16 columnas y 2 filas
  lcd.setBacklight(255);  // Activa la luz de fondo (0 para apagarla)
  lcd.setCursor(0, 0);    // Posiciona el cursor en la primera columna y fila
  lcd.print("INGRESAR CLAVE:");  // Muestra un mensaje en la pantalla
}

void loop() {
  // Verifica si hay datos disponibles desde el ESP32
  if (Serial.available() > 0) {
    // Lee la nueva contraseña enviada por el ESP32
    entradaesp32 = Serial.readString();
    entradaesp32.trim();  // Elimina espacios, saltos de línea y retornos de carro
    contrasena = entradaesp32;
    lcd.setCursor(0, 1);
    lcd.print(contrasena); // Muestra la nueva contraseña
    delay(3000);
    lcd.setCursor(0, 1);
    lcd.print("                "); // Limpia la segunda línea
  }

  char tecla = teclado.getKey(); // Lee una tecla del teclado

  if (tecla) {
    if (tecla == '#') {
      if (entrada == contrasena) {
        lcd.setCursor(0, 1);
        lcd.print("Abriendo puerta");
        digitalWrite(salida, HIGH);
        delay(tiempoActivo);
        digitalWrite(salida, LOW);
        lcd.setCursor(0, 1);
        lcd.print("Puerta Cerrada");
        delay(3000);
        lcd.setCursor(0, 1);
        lcd.print("                ");
        entrada = "";
      } else {
        lcd.setCursor(0, 1);
        lcd.print("Clave incorrecta");
        delay(3000);
        lcd.setCursor(0, 1);
        lcd.print("                ");
        entrada = "";
      }
    } else if (tecla == '*') {
      entrada = "";
      lcd.setCursor(0, 1);
      lcd.print("                ");
    } else {
      entrada += tecla;
      lcd.setCursor(0, 1);
      lcd.print(entrada);

      if (entrada.length() > 4) {
        entrada = "";
        lcd.setCursor(0, 1);
        lcd.print("max.4 caracteres");
        delay(3000);
        lcd.setCursor(0, 1);
        lcd.print("                ");
      }
    }
  }
}

[xfpd]

Wrap your formatted code in code tags using the <CODE> button in the reply/message box. The result should look like this:

void setup() {
}
void loop() {
}

You probably have switched column and row pins.

[ledsyn]

Translated the Spanish:

#include <Wire.h>
#include <Keypad.h>
#include <LiquidCrystal_PCF8574.h>

// Set the I2C address and LCD size
LiquidCrystal_PCF8574 LCD(0x27); Change 0x27 to your screen direction

// 4x4 Matrix Keyboard Setup
const byte rows = 4; Number of rows
const byte columns = 4; Number of columns

// Keymapping (adjusts according to your keyboard)
char keys[rows][columns] = {
{'1', '2', '3', 'A'},
{'4', '5', '6', 'B'},
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};

// Pins connected to the keyboard (adjusts according to your connection)
byte pinsRows[rows] = {9, 8, 7, 6}; Arduino Nano digital pins for rows
byte pinsColumns[columns] = {5, 4, 3, 2}; Arduino Nano digital pins for columns

Keypad keyboard = Keypad(makeKeymap(keys), pinsRows, pinsColumns, rows, columns);

// Password settings
String password="2016"; Correct password
String input = ""; Store user input
String inputes32 =""; Stores serial information from ESP32

// Setting up the digital output
const int output = 13; Arduino Nano digital pin for output (adjust according to your preference)
const unsigned long timeActive = 3000; Time in milliseconds (3 seconds)

void setup() {
// Initiate serial communication with the ESP32
Serial.begin(9600); Communication via RX and TX pins by default

// Setting up the digital output
pinMode(output, OUTPUT);
digitalWrite(output, LOW);

// Initialize the LCD
Wire.begin(); Start I2C communication
lcd.begin(16, 2); Initializes the LCD with 16 columns and 2 rows
lcd.setBacklight(255); Turn on the backlight (0 to turn it off)
lcd.setCursor(0, 0); Position the cursor in the first column and row
lcd.print("ENTER KEY:"); Display a message on the screen
}

void loop() {
// Check if data is available from ESP32
if (Serial.available() > 0) {
// Read the new password sent by the ESP32
inputsesp32 = Serial.readString();
inputsesp32.trim(); Eliminates gaps, line breaks, and carriage returns
password = entries esp32;
lcd.setCursor(0, 1);
lcd.print(password); Show the new password
delay(3000);
lcd.setCursor(0, 1);
lcd.print(" "); Clean up the second line
}

char key = keyboard.getKey(); Read a key on the keyboard

if (key) {
if (key == '#') {
if(input == password) {
lcd.setCursor(0, 1);
lcd.print("Opening door");
digitalWrite(output, HIGH);
delay;
digitalWrite(output, LOW);
lcd.setCursor(0, 1);
lcd.print("Closed Door");
delay(3000);
lcd.setCursor(0, 1);
lcd.print(" ");
input = "";
} else {
lcd.setCursor(0, 1);
lcd.print("Incorrect key");
delay(3000);
lcd.setCursor(0, 1);
lcd.print(" ");
input = "";
}
} else if (key == '*') {
input = "";
lcd.setCursor(0, 1);
lcd.print(" ");
} else {
input += key;
lcd.setCursor(0, 1);
lcd.print(input);

if(input.length() > 4) {
    input = "";
    lcd.setCursor(0, 1);
    lcd.print("max.4 characters");
    delay(3000);
    lcd.setCursor(0, 1);
    lcd.print(" ");
  }
}

}
}

[xfpd]

Your pins are backwards.

[sonofcy]

The 1, 5, 9, D is a clue.

[ledsyn]

@xfpd

You probably have switched column and row pins.

You nailed it. Since 1,5,9,D work.

[MaximoEsfuerzo]

Did you verify that the matrix is ​​the same as the one on the bubble keypad (the one in the first photo)?
With a tester in continuity mode (or the lowest resistance scale) test which pins have continuity when you press each key, so you can identify each row and each column.

[soviet_otaku]

Yes, however it seems to be more a thing of code or arduino nano, because the same order of connection for rows and columns was used at arduino uno and worked with no problems.

[ledsyn]

Could be a difference there. But try it out, switch the pins!

[MaximoEsfuerzo]

There are no differences between UNO and Nano except that the latter has 2 more analog pins. If it works on UNO, it works on Nano.