2*4 matrix keyboard/8 keys independent key module

#include <Keypad.h>

// Define the number of rows and columns
const byte ROWS = 2;  // Two rows
const byte COLS = 4;  // Four columns

// Define the symbols printed on the keypad buttons
char keys[ROWS][COLS] = {
  {'1','2','3','4'},
  {'5','6','7','8'}
};

// Define the Arduino pins connected to the module's rows and columns
byte rowPins[ROWS] = {9, 8};    // R1, R2
byte colPins[COLS] = {7, 6, 5, 4};  // C1, C2, C3, C4

// Create the Keypad object
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(9600);
  Serial.println("2x4 Matrix Keyboard Ready. Press any key...");
}

void loop() {
  char key = keypad.getKey();  // Check for a key press
  
  if (key) {  // If a key was pressed
    Serial.print("Key Pressed: ");
    Serial.println(key);
    
    // Add your action code here based on which key was pressed
    switch(key) {
      case '1':
        // Action for key 1
        break;
      case '2':
        // Action for key 2
        break;
      // Add more cases for keys 3-8 as needed
    }
  }
}

// Define row and column pins
int rowPins[] = {9, 8};
int colPins[] = {7, 6, 5, 4};

void setup() {
  Serial.begin(9600);
  
  // Set row pins as outputs, initially LOW
  for (int i = 0; i < 2; i++) {
    pinMode(rowPins[i], OUTPUT);
    digitalWrite(rowPins[i], LOW);
  }
  
  // Set column pins as inputs with pull-ups
  for (int i = 0; i < 4; i++) {
    pinMode(colPins[i], INPUT_PULLUP);
  }
}

void loop() {
  for (int row = 0; row < 2; row++) {
    // Set the current row HIGH
    digitalWrite(rowPins[row], HIGH);
    
    // Check each column
    for (int col = 0; col < 4; col++) {
      if (digitalRead(colPins[col]) == LOW) {
        // Key pressed: calculate key number and break
        int keyNumber = row * 4 + col + 1;
        Serial.print("Key ");
        Serial.println(keyNumber);
        delay(200);  // Simple debounce
      }
    }
    
    // Reset the row to LOW before moving to the next row
    digitalWrite(rowPins[row], LOW);
  }
  
  delay(50);  // Small delay between scans
}

from pad4pi import rpi_gpio
import time

# Define key mapping
KEY_MAP = [
    ["1", "2", "3", "4"],
    ["5", "6", "7", "8"]
]

# Define GPIO pins connected to rows and columns
ROW_PINS = [9, 8]      # GPIO pins for rows
COL_PINS = [7, 6, 5, 4]  # GPIO pins for columns

factory = rpi_gpio.KeypadFactory()
keypad = factory.create_keypad(keypad=KEY_MAP, row_pins=ROW_PINS, col_pins=COL_PINS)

def print_key(key):
    print(f"Key Pressed: {key}")

keypad.registerKeyPressHandler(print_key)

try:
    while True:
        time.sleep(0.1)
except KeyboardInterrupt:
    keypad.cleanup()