SH7216 Datasheet, PDF (15/32 Pages) Renesas Technology Corp – USB Mass Storage Class

SH7216 Group
USB Function Module: USB Mass Storage Class
5.2 USB Communication State
The USB communication state can be further divided into three states according to the transfer type (see figure 6).
When an interrupt occurs, first there is a transition to the USB communication state, and then there is further branching
to a transfer state according to the interrupt type.
Control transfer
USB communication state
Bulk transport
Ready
Setup stage
Ready
Command
transport (CBW)
Data stage
OUT direction
Data stage
IN direction
Data out
Data in
Status stage
Status transport (CSW)
Figure 6 USB Communication State
5.2.1 Control Transfer
Control transfer is used mainly for functions such as obtaining device information and specifying device operating
states. For this reason, when the function is connected to the host PC, control transfer is the first transport to be carried
out.
Transport processing for control transfer is carried out in a series of two or three stages. These stages are a setup stage, a
data stage, and a status stage.
5.2.2 Bulk Transport
Bulk transport has no time limitations, so it is used to send large volumes of data with no errors. The data transport
speed is not guaranteed, but the data contents are guaranteed. With USB Mass Storage Class (Bulk-Only Transport),
bulk transport is used to transfer storage data between the host PC and the function.
Transport processing for USB Mass Storage Class (Bulk-Only Transport) is carried out in a series of two or three stages.
These stages are command transport (CBW), data transport, and status transport (CSW).
REJ06B0897-0100/Rev.1.00
July 2009
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