2.2. An HID Report Example analysis

2.2. An HID Report Example analysis
	第 2 章 HID Report Example

Follow is the example.

According to the format, defined in specification:

图 2.4. HID Data Format

Now to analysis the corresponding meaning for every group bytes:

	Data send by LSB
	The data is send by LSB, so when “0x45, 0xFF’ is sent, first send is “0x45”, second send “0xFF”, the LSB is “0x45” located in low address, the MSB “0xFF” located in high address, so the hex value is ”0xFF45“

	0x06, 0x45, 0xFF,
	0x0A, 0x00, 0xA0,
	0xA1, 0x01,
	0x75, 0x08,
	0x96, 0x07, 0x01,
	0x15, 0x00,
	0x26, 0xFF, 0x00,
	0x0A, 0x01, 0xA0,
	0x91, 0x02,
	0x75, 0x08,
	0x95, 0x08,
	0x0A, 0x02, 0xA0,
	0x81, 0x02,
	0xC0

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x06
0xFF	0x45	0000	01	10	0000 0110
0xFF45 -> 0xFF00 -0xFFFF = Vendor defined		Usage Page	Global item	2 bytes

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x0A
0xA0	0x00	0000	10	10	0000 1010
Usage=0xA000		Usage	Local item	2 bytes

here Usage=0xA000 is just self defined, just need not confict with self's others, no other special meaning

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0xA1
	0x01	1010	00	01	1010 0001
	Application (mouse, keyboard)	Collection	Main item	1 bytes

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x75
	0x08	0111	01	01	0111 0101
	Report Size = 0x08 bits	Report Size	Global item	1 bytes

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x96
0x01	0x07	1001	01	10	1001 0110
Report Count = 0x0107=263		Report Count	Global item	2 bytes

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x15
	0x00	0001	01	01	0001 0101
	Logical Minimum = 0x00	Logical Minimum	Global item	1 bytes

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x26
0x00	0xFF	0010	01	10	0010 0110
Logical Maximum =x00FF=255		Logical Maximum	Global item	2 bytes

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x0A
0xA0	0x01	0000	10	10	0000 1010
Usage = 0xA001		Usage	Local item	2 bytes

here Usage=0xA001 is just self defined, just need not confict with self's others, no other special meaning

[Data]

bTag=7:4

bType=3:2

bSize=1:0

0x91

0x02

1001

1001 0001

0x02=0000 0010

Bit 1 { Variable (1)}

All other bits are Reserved (0)

Output

Main item

1 bytes

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x75
	0x08	0111	01	01	0111 0101
	Report Size = 0x08 bits	Report Size	Global item	1 bytes

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x95
	0x08	1001	01	01	1001 0101
	Report Count= 0x08 = 8	Report Count	Global item	1 bytes

[Data]	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0x0A
0xA0	0x02	0000	10	10	0000 1010
Usage = 0xA002		Usage	Local item	2 bytes

[Data]

bTag=7:4

bType=3:2

bSize=1:0

0x81

0x02

1000

1000 0001

0x02=0000 0010

Bit 1 { Variable (1)}

All other bits are Reserved (0)

Input

Main item

1 bytes

	[Data]	bTag=7:4	bType=3:2	bSize=1:0	0xC0
		1100	00	00	1100 0000
Closes an item collection		End Collection	Main item	0 bytes

After analyze following data, the summary is:

Usage Page (0xFF45)	=Vendor-Specific	0xFF45 06	Global
Usage (0xA000)		0xA000 0A	Local
Collection (Application)		0x01 A1	Main
	Report Size (8)	0x08 75	Global
	Report Count (263)	0x0107 96	Global
	Logical Minimum (0)	0x00 15	Global
	Logical Maximum (255)	0x00FF 26	Global
	Usage (0xA001)	0xA0001 0A	Local
	Output (Variable)	0x02 91	Main
	Report Size (8)	0x08 75	Global
	Report Count (8)	0x08 95	Global
	Usage (0xA002)	0xA002 0A	Local
	Input (Variable)	0x02 81	Main
End Collection		0xC0	Main

Report (Usage=0xA0000)
	Output Report (Usage=0xA001)
263 bytes	Byte 0
	Byte 1
	...
	...
	Byte 261
	Byte 262

	Input Report (Usage=0xA002)
8 bytes	Byte 0
	Byte 1
	...
	Byte 7

All of above means:

This is a vendor-specific HID device
input or output is relative to Host side:
- Output = Host ⇒ Device = host send 263 bytes to device
- Input = Host ⇐ Device = device send 8 bytes to host
Every bytes value range is 0~255