GPUSB101A datasheet(22/37 Pages) GENERALPLUS

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GPUSB101A

Proprietary & Confidential

Sep 24, 2014

Version: 1.4

dCBWSignature:

Signature that helps identify this data packet as a CBW. The

signature field shall contain the value 43425355h (little endian),

indicating a CBW.

dCBWTag:

A Command Block Tag sent by the host. The device shall echo

the contents of this field back to the host in the dCSWTag field of

the associated CSW.

The dCSWTag positively associates a

CSW with the corresponding CBW.

dCBWDataTransferLength:

The number of bytes of data that the host expects to transfer on

the Bulk-In or Bulk-Out endpoint (as indicated by the Direction bit)

during the execution of this command. If this field is zero, the

device and the host shall transfer no data between the CBW and

the associated CSW, and the device shall ignore the value of the

Direction bit in bmCBWFlags.

bmCBWFlags:

The bits of this field are defined as follows:

Bit 7 Direction - the device shall ignore this bit if the

dCBWDataTransferLength field is zero, otherwise:

0 = Data-Out from host to the device,

1 = Data-In from the device to the host.

Bit 6 Obsolete. The host shall set this bit to zero.

Bits 5...0 Reserved - the host shall set these bits to zero.

bCBWLUN:

The device Logical Unit Number (LUN) to which the command

block is being sent. For devices that support multiple LUNs, the

host shall place into this field the LUN to which this command

block is addressed. Otherwise, the host shall set this field to

zero.

bCBWCBLength:

The valid length of the CBWCB in bytes. This defines the valid

length of the command block.

The only legal values are 1

through 16 (01h through 10h). All other values are reserved.

CBWCB:

The command block to be executed by the device. The device

shall interpret the first bCBWCBLength bytes in this field as a

command block as defined by the command set identified by

bInterfaceSubClass. If the command set supported by the device

uses command blocks of fewer than 16 (10h) bytes in length, the

significant bytes shall be transferred first, beginning with the byte

at offset 15 (Fh). The device shall ignore the content of the

CBWCB field past the byte at offset (15 + bCBWCBLength - 1).

10.3.2. Command Status Wrapper (CSW)

The CSW shall start on a packet boundary and shall end as a

short packet with exactly 13 (0Dh) bytes transferred.

Fields

appear aligned to byte offsets equal to a multiple of their byte size.

All CSW transfers shall be ordered with the LSB (byte 0) first (little

endian). Refer to the USB Specification Terms and Abbreviations

for clarification.

TABLE 7.3.2. Command Status Wrapper

GPUSB101A Datasheet(PDF) 22 Page - Generalplus Technology Inc.

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