The PCB must be mounted floated, otherwise key presses don't work reliable. Connect pins 3 and 4 on connector P1 for 16-pin button mode. Smaller keypads with less pins may work, but are not tested.
Moving the joystick along X-Axis 1 (or D-Pad left and right) acts as if you pressed the Left / Right Arrow keys on the keyboard. Moving the joystick along X-Axis 1 (or D-Pad left and right) move the ...