Welcome @Akshunhiro,
If the buttons are momentary contact type you could also just wire each one directly to the adruino using internal pull-up resistors, no additional components required.
Here is an Instructables I found that describes the technique: https://www.instructables.com/Arduino-Bu...-resistor/
You would just have to replace the LED pin writes with keypresses in your code. Some sort of debouncing code would also be a good idea.
If you don't feel comfortable writing your own code you might be able to find a complete example by searching for 'arduino HID keypad' or 'arduino HID keyboard'
One more thought, If you do go the resistor ladder route look into the built in support added to OAP in version 14:
https://bluewavestudio.io/community/showthread.php?tid=2208&pid=16378#pid16378
To use that method (resistive buttons) you would need either an ads1105 or ads1115 analog to digital convertor wired directly to the Pi.
You could also wire each button directly to the Pi and use the GPIO controller service but I would avoid that route in case you need to use the pins on the pi for something else in the future.
EDIT: just noticed you are already looking into resistive buttons controller services in another thread
If the buttons are momentary contact type you could also just wire each one directly to the adruino using internal pull-up resistors, no additional components required.
Here is an Instructables I found that describes the technique: https://www.instructables.com/Arduino-Bu...-resistor/
You would just have to replace the LED pin writes with keypresses in your code. Some sort of debouncing code would also be a good idea.
If you don't feel comfortable writing your own code you might be able to find a complete example by searching for 'arduino HID keypad' or 'arduino HID keyboard'
One more thought, If you do go the resistor ladder route look into the built in support added to OAP in version 14:
https://bluewavestudio.io/community/showthread.php?tid=2208&pid=16378#pid16378
To use that method (resistive buttons) you would need either an ads1105 or ads1115 analog to digital convertor wired directly to the Pi.
You could also wire each button directly to the Pi and use the GPIO controller service but I would avoid that route in case you need to use the pins on the pi for something else in the future.
EDIT: just noticed you are already looking into resistive buttons controller services in another thread