If you are using a USB extension cable, cut it in half and expose the four cables. Keep the socket end, as the goal is to plug a controller into this cable.
Hook up the V+ / VBUS (Red) to the VBUS pin on your Pi Pico
Hook up the V- / GND (Black) to ground on your Pi Pico
Hook up D+ (Green) to one side of a 27ohm resistor and the other side to a unused digital pin.
Hook up D- (White) to one side of a 27ohm resistor and the other side to the digital pin directly after D+. For example, you can hook up D+ to GP2 and D- to GP3.
Connect a 47pF capacitor between D+ and ground
Connect a 47pF capacitor between D- and ground
Wiring Steps (without capacitor and resistor)
If you are using a USB extension cable, cut it in half and expose the four cables. Keep the socket end, as the goal is to plug a controller into this cable.
Hook up the V+ / VBUS (Red) to the VBUS pin on your Pi Pico
Hook up the V- / GND (Black) to ground on your Pi Pico
Hook up D+ (Green) to a unused digital pin.
Hook up D- (White) to the digital pin directly after D+. For example, you can hook up D+ to GP2 and D- to GP3.
Configuring
Click on Add setting
Find and add USB Host inputs
Bind D+
Hit Save
Click on Add setting
Find and add MIDI inputs
Hit Save
For pro keys, you will need to pick what key your keyboard starts at. You can hit Click to assign and then press a note on your keyboard, and that will be mapped to the Pro Keys note, with every other note being assigned to the next notes in order.
If you plug in a supported controller, the tool should detect it and tell you what it is. Most controllers are supported, but things like the play and charge kit won't work over USB.