Cypress CY4672 manual Ping Packet Bridge, Data Packet/Back Channel Data Packet Bridge and HID

WirelessUSB™ Protocol 2.2

2.3.5Ping Packet (Bridge)

Byte		1
Bits:	7:4	3:1	0
Field:	3	Reserved	Flag

Byte 1

Packet Type: 3

Flag (F): This is a 1-bit field that specifies a ping or ping response (0 = Ping, 1 = Ping Response).

2.3.6Data Packet/Back Channel Data Packet (Bridge and HID)

Data packets are sent from the HID to the bridge in connected mode. They are also sent from the bridge to the HID in connected mode if there is an asynchronous back channel.

Byte			1
Bits:	7:4	3	2	1	0
Field:	4 / 5	BCDR	Toggle	DT0	DT1

2

7:0

Byte 1

..

7:0

..

7:0

N

7:0

Byte N

Byte 1

Data Packet Type:

4 = Data Packet type

5 = Back Channel Packet Type

BCDR: This is a 1-bit field used to request back channel data. Setting this bit indicates to the bridge that the HID will be listening for data following the transaction.

Data Toggle Bit: This is a 1-bit field that is toggled for each new data packet. It is used to distinguish between new and retransmitted packets.

Data Device Type 0/1: This is a 2-bit field that specifies a vendor-defined device type. This allows the bridge to determine HID type. The two bits are swapped in order to be backward compatible. In most cases the data device type is the same as the device type in the bind request and connect request. However, they may differ when one device tries to simulate the other device, for instance, the key- board simulates the mouse.

DT0=0, DT1= 0	Presenter (0x0)
DT0=1, DT1= 0	Undefined (0x1)
DT0=0, DT1= 1	Keyboard (0x2)
DT0=1, DT1= 1	Mouse (0x3)

Byte 2-N

Data Byte 0–N: This is byte-aligned application data.

CY4672 Reference Design Guide, Document # 001-16968 Revision ** 25

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