One of the most mysterious things about these keypads is that they usually come with no documentation, so a user is left to figure out the pin configuration for him or herself. However, we at this site, have figured it out.

With the keypad facing up so that the keys are up and facing you, from left to right, the 1st 4 pins are the row pins and the last 4 pins are the column pins.

Connections of this project are straight and simple as shown above.

• Connect pin 1 of keypad to pin 9 of Arduino.

• Start connecting the pins leftwards now. 2 with 8, 3 with 7, 4 with 6, etc.

Now, upload the program and open the Serial Monitor. Then, open the Serial Monitor. Then, press any button and you will be able to see the corresponding character of the screen.

For further help, you can go to this link which will run the simulator made by me on Tinkercad for more easy understanding.