notes.md

Notes on USB HID

Useful Links

Specs

USB HID Definition

USB HID Usage Tables

Tools

USB HID Report Parser

Definition

Following the format of the coding sample on page 25 of the HID Definition

Usage Page (Generic Desktop),
Usage(Game Pad),                                        ; An arcade-style joystick probably doesn't actually meet the requirements for a joystick?
    Collection(Application),
        Usage(Pointer),
            Collection(Physical),
            Usage(X),
            Usage(Y),
            Logical Minimum(-1),
            Logical Maximum(1),
            Report Count(2),
            Report Size(2),
            Input(Data, Variable, Absolute, No Null),   ; 2-bit signed integer X axis
        End Collection(),
        Usage Minimum(D-Pad Up),
        Usage Maximum(D-Pad Left),
        Report Count(4),
        Report Size(1),
        Input(Data, Variable, Absolute),                ; are the D-Pad buttons necessary in practice?
        Usage Page (Buttons),
        Usage Minimum (1),
        Usage Maximum (12),
        Logical Minimum(0),
        Logical Maximum(1),
        Report Count(12),
        Report Size(1),
        Input(Data, Variable, Absolute)
        Report Count(1),
        Report Size(4),
        Input(Constant),
    End Collection,
End Collection

Relevant Codes

Uasage Page	Code
Generic Desktop	0x01
Button page	0x09

Usage	Page	Code
Joystick	Generic Desktop	0x04
Game Pad	Generic Desktop	0x05
Pointer	Generic Desktop	0x01
X	Generic Desktop	0x30
Y	Generic Desktop	0x31
Start	Generic Dektop	0x3D
Select	Generic Desktop	0x3E
D-Pad Up	Generic Desktop	0x90
D-Pad Down	Generic Desktop	0x91
D-Pad Left	Generic Desktop	0x92
D-Pad Right	Generic Desktop	0x93

Type	Code
Main	1
Global	2
Local	3
Reserved	4

Tag	Bits	Hex (First Byte and 0 size)
Input	1000 00 nn	0x80
Output	1001 00 nn	0x90
Feature	1011 00 nn	0xA0
Collection	1010 00 nn	0xB0
End Collection	1100 00 nn	0xC0
Usage Page	0000 01 nn	0x04
Logical Minimum	0001 01 nn	0x14
Logical maximum	0010 01 nn	0x24
Report Size	0111 01 nn	0x74
Report Count	1001 01 nn	0x94
Usage	0000 10 nn	0x08
Usage Minimum	0001 10 nn	0x18
Usage Maximum	0010 10 nn	0x28

C Array body

0x05, 0x01, // Usage Page (Generic Desktop),
0x09, 0x05, // Usage(Game Pad),
0xA1, 0x01, // Collection(Application),
    0x09, 0x01, // Usage(Pointer),
    0xA1, 0x00, // Collection(Physical),
        0x09, 0x30, // Usage(X),
        0x09, 0x31, // Usage(Y),
        0x15, 0xFF, // Logical Minimum(-1),
        0x25, 0x01, // Logical Maximum(1),
        0x95, 0x02, // Report Count(2),
        0x75, 0x02, // Report Size(2),
        0x81, 0x02, // Input(Data, Variable, Absolute, No Null), 
    0xC0, // End Collection(),
    0x19, 0x90, // Usage Minimum(D-Pad Up),
    0x29, 0x93, // Usage Maximum(D-Pad Left),
    0x95, 0x04, // Report Count(4),
    0x75, 0x01, // Report Size(1),
    0x81, 0x02, // Input(Data, Variable, Absolute),
    0x05, 0x09, // Usage Page (Buttons),
    0x19, 0x01, // Usage Minimum (1),
    0x29, 0x0C, // Usage Maximum (12),
    0x15, 0x00, // Logical Minimum(0),
    0x25, 0x01, // Logical Maximum(1),
    0x95, 0x0C, // Report Count(12),
    0x75, 0x01, // Report Size(1),
    0x81, 0x02, // Input(Data, Variable, Absolute)
    0x95, 0x01, // Report Count(1),
    0x75, 0x04, // Report Size(4),
    0x81, 0x01, // Input(Constant),
0xC0 // End Collection

Report Format

Byte	7	6	5	4	3	2	1	0
0	D-Pad Right	D-Pad Left	D-Pad Down	D-Pad Up	Pointer Y		Pointer X
1	Button 8	Button 7	Button 6	Button 5	Button 4	Button 3	Button 2	Button 1
2	Pad				Button 12	Button 11	Button 10	Button 9