GPUSB101A

© Generalplus Technology Inc.

Proprietary & Confidential

21

Sep 24, 2014

Version: 1.4

10.3. USB Bulk Only Command Protocol

GPUSB101A must receive USB vendor command from USB Host (PC). The command format is following USB mass storage device

class command.

Figure 1 - Command/Data/Status Flow shows the flow for Command Transport, Data-In, Data-Out and Status Transport. The following

sections define Command and Status Transport.

10.3.1. Command Block Wrapper (CBW)

The CBW shall start on a packet boundary and shall end as a short packet with exactly 31 (1Fh) bytes transferred. Fields appear aligned

to byte offsets equal to a multiple of their byte size. All subsequent data and the CSW shall start at a new packet boundary. All CBW

transfers shall be ordered with the LSB (byte 0) first (little endian). Refer to the USB Specification Terms and Abbreviations for

clarification.

TABLE 7.3.1. Command Block Wrapper