SH7286 Group
USB Function Module: USB Mass Storage Class
5.2
USB Communication State
The USB communication state is divided into two states according to the type of data transfer (See Figure 6). When an
interrupt occurs, the SH7286 transitions to the USB communication state, and then jumps to each state according to the
type of interrupts.
Data out
Data in
Status transport (CSW)
Command
transport (CBW)
Ready
Bulk transport
USB communication state
Data stage
OUT direction
Data stage
IN direction
Ready
Control transfer
Status stage
Setup stage
Figure 6 USB Communication State
5.2.1 Control
Transfer
Control transfer is used to retrieve the device information and set the device state, which is executed immediately after
the function is connected to the host.
Control transfer consists of two or three stages, Setup stage, Data stage, and Status stage.
5.2.2 Bulk
Transfer
Bulk transfer is used to transfer large amount of data untimely but without any error. Transfer speed is not guaranteed,
however, the delivery of the data is guaranteed. USB Mass Storage Class (Bulk-Only Transport) uses bulk transfer to
send the data from the function to the host computer.
USB Mass Storage Class (Bulk-Only Transport) data transfer (read/write) is composed of two or three stages,
Command transport (CBW), Data transport, and Status transport (CSW).
R01AN0063EJ0100 Rev. 1.00
Page 16 of 32
Oct. 22, 2010
