For the Micro, Leonardo and Pro Micro, please pick the type of device you have in the dropdown.
You will be met with the following screen (Note that it will be slightly different for an Arduino Uno or Arduino Mega) Your Arduino should show up, like in the following image.
Connect the gnd pin on the wii breakout / extension cable to the gnd on your Arduino.
For all devices except the 3.3v Pro Micro, you will need to hook a 3.3v voltage regulator to the Arduino first, and then connect the 3.3v output of the regulator to the ps2 controller's 3.3v pin.
Connect the 3.3v pin on the ps2 controller to the 3.3v pin on your Arduino.
For an Arduino Uno, pin 11 is MOSI, pin 12 is MISO and pin 13 is SCK.
For an Arduino Pro Micro (3.3v), Leonardo or Micro, the SCK pin is pin 15, the MOSI pin is pin 16 and the MISO pin is pin 14.
Note that for anything that isn't the 3.3v pro micro, you will need to connect these pins using a level shifter.
Connect Command to MOSI, Data to MISO and Clock to SCK.
Note that for anything that isn't the 3.3v pro micro, you will need to connect this pin using a level shifter. Refer to the following image for the pinout of a PS2 controller. If you pick the wrong voltage, your device won’t show up and you will need to follow the rescuing instructions to make it show up again! The finished product (When using a 3.3v Pro Micro and dupont wires) Be careful when programming an Arduino that has multiple variants.