Input streaming protocol

Console Port Pad Port Direction
50022 50122 Console → Pad

The input protocol, also known as HID protocol, is used to send input device status from the GamePads to the Wii U. It is a very simple protocol: a 128 bytes blob contains the status of most input methods supported by the Wii U, and it is sent by each GamePad 180 times per second.

The 128 bytes blob is generated on the UIC and received unmodified by IOSu on the console.

../../_images/input-data-path.png

Input data format

struct InputData {
    u16 seq_id;
    u16 buttons;  // see ButtonsMask
    u8 power_status;  // see PowerStatusMask
    u8 battery_charge;
    u16 left_stick_x;
    u16 left_stick_y;
    u16 right_stick_x;
    u16 right_stick_y;
    u8 audio_volume;
    AccelerometerData accelerometer;
    GyroscopeData gyro;
    MagnetData magnet;
    TouchscreenData touchscreen;
    char unk0[4];
    u8 extra_buttons;  // see ExtraButtonsMask
    char unk1[46];
    u8 fw_version_neg;  // ~fw_version
};

enum ButtonsMask {
    SYNC = 0x0001,
    HOME = 0x0002,
    MINUS = 0x0004,
    PLUS = 0x0008,
    R = 0x0010,
    L = 0x0020,
    ZR = 0x0040,
    ZL = 0x0080,
    DOWN = 0x0100,
    UP = 0x0200,
    RIGHT = 0x0400,
    LEFT = 0x0800,
    Y = 0x1000,
    X = 0x2000,
    B = 0x4000,
    A = 0x8000
};

enum PowerStatusMask {
    AC_PLUGGED_IN = 0x01,
    POWER_BUTTON_PRESSED = 0x02,
    CHARGING = 0x40,
    POWER_USB = 0x80,  // not used on retail
};

struct AccelerometerData {
    s16 x_accel;
    s16 y_accel;
    s16 z_accel;
};

struct GyroscopeData {
    s24 roll;
    s24 yaw;
    s24 pitch;
};

struct MagnetData {
    char unknown[6];
};

struct TouchscreenData {
    // 10 points are sampled at about the same time - average them to get
    // a more accurate reading.
    struct {
        struct {
            u16 pad : 1;
            u16 extra : 3;  // See the next section.
            u16 value : 12;
        } coords[2];
    } points[10];
};

enum ExtraButtonsMask {
    TV = 0x20,
    R3 = 0x40,
    L3 = 0x80,
};

Touchscreen extra data

Each touchscreen coordinate is used to store additional information:

Touchscreen pressure
Stored as a 12 bit integer in the extra data of the first two points. It is not yet known how to translate this value to a usable pressure value - currently it is assumed to be a resistance value reading.
UIC firmware version
16 bit integer stored in the extra data of points 6 to 8 (only one bit of the first coordinate of point 6 is used).