How the N64 analog stick functions
The Nintendo 64 controller was one of the first game controllers to include an analog stick. The N64 analog stick provided users with greater functionality, including improved mobility and camera control. Unlike the D-pad, which detects only 8 directions, the analog stick can detect 360 independent directions. This enhanced capability allowed Nintendo 64 games to accurately emulate a full 360° range of motion.
The N64 analog stick utilizes optical encoding disks, similar to how ball mice operate, to determine its position. However, these disks only provide relative changes in the stick’s position. Upon powering on, the system assumes that the stick is centered and tracks relative movements from there. In case of any synchronization issues or if the stick wasn’t centered during power-on, you can reset the center position by simultaneously pressing the left and right shoulder buttons (L and R) along with the Start button.
While the optical encoding disks offer mostly digital signals and highly accurate relative movements, cheaper potentiometers are often used in third-party controllers and joysticks. These potentiometers allow the controller to track the absolute position of the joystick, but since the signal is analog, it tends to be noisy and may fluctuate even if the N64 analog stick remains stationary.
How the optical encoders work
Whenever you move the N64 analog stick, these wheels turn slightly. Each wheel has tiny slots arranged around its perimeter. Positioned between each wheel and a photocell is an LED (Light Emitting Diode). When the light from the LED shines through the slots in the wheel and reaches the photocell, a small amount of current is created. As the amount of light changes, the level of current also changes. By monitoring the output of each photocell, the N64 can accurately determine the precise angle at which the joystick is being held and activate the appropriate response (https://electronics.howstuffworks.com/n64.htm)
- The stick and parts use ABS plastic: https://www.reddit.com/r/n64/comments/839vpi/n64_controller_parts_material/
- A link to demonstrate how the joystick turns and how many angles it has, way more than 360: https://n64squid.com/n64-joystick-360-degrees/