Problem with keypad

Projects Networking, Protocols, and Devices
1

Hello guys,
I have keypad but it isn't a standard keypad, I did remove this part from old alarm controller from my grandpa shop. Could you help me how connect this in Arduino? First I thought the first four pins are columns and next eight pins are rows but when I connect that and when I send to Serial.Begin data then only have once char from matrix working and every button on column send the same char... below I putting the picture about this keypad. btw I can't found any manual for this part

Picture 1

Picture 2

#include <Keypad.h>

const byte ROWS = 8; //eight rows
const byte COLS = 4; //five columns
//define the symbols on the buttons of the keypads
char hexaKeys[ROWS][COLS] = {
  {'S'},            // start
  {'A','B'},        // f1....
  {'C','D','E',}, 
  {'7','8','9'},   
  {'4','5','6'},
  {'1','2','3'},
  {'*','0','+'},
  {'_', '<', ']' }     
};

byte rowPins[ROWS] = {10, 12, 11, 10, 9, 8, 7, 6}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {2, 3, 4, 5}; //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);
}
  
void loop(){ 
  char customKey = customKeypad.getKey();  
  if (customKey) 
  {       // print keys 
        Serial.print(customKey);
  }
}
2

@OP

1. This is the structure of the Keypad which we use with UNO and Keypad.h Library.
keyStructure.png

2. These are the backside/frontside of your keypad.
keystruc.png
Key3rd.png

Please, use a DVM to find Rows and Columns for each key of your keypad. Once you have found it, make a schematic and post it here. We will help to map your keypad with the Keypad.h library of Arduino.

Or

You may try the following approach, which I believe will match with the Keypad.h Librray.
key3rdX.png

keyStructure.png

keystruc.png

Key3rd.png

key3rdX.png

3

Sorry for delay. I resolved problem with DVM, use Ω for check resistance. I print simple schema and start checking measurements. I was surprised, because pin2 connected to 6 blocked the keyboard, so I completely excluded pin 6 which did not show any resistance below schema. Thank a lot for targeting check resistance.

IMG_0943.JPG
IMG_0943.JPG3024×4032 1.73 MB

4

@OP

I am sorry if something does not agree with your assessment.

1. We should label the columns as C1, C2, C3, and C4 starting from left in order to remain aligned with the Keypad of the UNO so that Keypad.h Library could be used. Unfortunately, you have used C0, C1, ...

2. Let us look at the backside of your Keypad. It clearly indicates that there are 6 keys in C1 (Column - 1). I have shown 6 in my diagram; but, you have shown all the 7 keys in C1 (your C0).

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