4x3 keypad not providing any output and the output it does provide is incorrect

Question

I am trying to figure out how to use a 4x3 keypad and just want to receive the key numbers I select on the serial monitor. The problem I am getting is that some of the keys I type don't give me any output and then the keys that do provide output do not match their corresponding number. For example key 1 does not provide any output, whereas keys 3 and 4 give an output of 4 and 9 respectively. I have attached pictures of how the keypad is connected Wiring that I used to connect the pins Close up of the pins wire diagram

The code that I am using is below:

#include <Keypad.h>
 
// Constants for row and column sizes
const byte ROWS = 4;
const byte COLS = 3;
 
// Array to represent keys on keypad
char hexaKeys[ROWS][COLS] = {
 {'1', '2', '3'},
 {'4', '5', '6'},
 {'7', '8', '9'},
 {'*', '0', '#'}
};
 
// Connections to Arduino
byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {5, 4, 3};
 
// Create keypad object
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);
 
void setup() {
 // Setup serial monitor
 Serial.begin(9600);
}
 
void loop() {
 // Get key value if pressed
 char customKey = customKeypad.getKey();
 
 if (customKey) {
 // Print key value to serial monitor
 Serial.println(customKey);}
}

I just need help identifying where I am going wrong and how I can fix the problem I am having. Thanks.

• Gil: Your pictures are useless to me, post a real schematic as to how you have it wired. I know first hand the keyboards will work if connected correctly to a good UNO. Be sure to show the keyboard in the schematic and properly label rows and columns.
• Nick Gammon: Are those pins soldered onto the keypad? The connection looks a bit dodgy from the photo.
• Campbell White: Hi Gil, I have included a schematic, however, I could only find a 4x4 keypad so just ignore the connection to pin 2. Hi Nick, yes they are soldered onto the keypad.

Answer 1

I determined where I was going wrong. The keypad has a different wiring compared to the traditional way of doing it. I found this this article helpful. The changes made to the code are as follows:

byte rowPins[ROWS] = {8, 3, 4, 6};
byte colPins[COLS] = {7, 9, 5};

As can be seen, the rows and columns pins need to be changed.

Diagram showing what connections are for rows and which ones are for columns