How are the many signals of a N64 or Wii joystick sent to the console by only 2 wires

controllersnintendo-64nintendo-wii

I am curious as to how only 2 wires (perhaps 3 or 4) inside a N64 or Wii gamepad are able to send the many signals of the different inputs at once.

It used to be that for just one ON/OFF input, we needed two wires. So why does it not take dozens of wires for the many inputs on a modern gamepad?

Best Answer

So the Wii Joystick uses a Blue Tooth interface which is a little different than the N64 controller. As a result this answer deals more with the latter than the former.

The N64 controller uses a single transmission wire on which it encodes bits to send signals back to the N64 console. To accomplish this bits are encoded on that wire as follows:

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This encoding can then be used to multiplex the connection and allow 32 bit communication. In the case of the N64 controller these bits are encoded thus:

0   A
1   B
2   Z
3   Start
4   Directional Up
5   Directional Down
6   Directional Left
7   Directional Right
8   unknown (always 0)
9   unknown (always 0)
10  L
11  R
12  C Up
13  C Down
14  C Left
15  C Right

With the remaining 16 bits being used for the Analog Joystick (providing 8 degrees of control).

More over, certain codes are transmitted for specialized function:

To Init: send 03 80 01 followed by 34 80's
To Start Rumble: 03 c0 1b followed by 32 01's
To Stop Rumble: 03 c0 1b followed by 32 00's

You can find more information in this vein here

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