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Section 20 USB Function Module
Rev. 4.00 Sep. 14, 2005 Page 768 of 982
REJ09B0023-0400
20.4.3 Control Transfer
Control transfer consists of three stages: setup, data (not always included), and status (figure 20.4).
The data stage comprises a number of bus transactions. Operation flowcharts for each stage are
shown below.
Control IN
Setup stage Data stage Status stage
Control OUT
No data
SETUP(0)
DATA0
SETUP(0)
DATA0
SETUP(0)
DATA0
IN(1)
DATA1
OUT(1)
DATA1
IN(0)
DATA0
OUT(0)
. . .
. . .
DATA0
IN(0/1)
DATA0/1
OUT(0/1)
DATA0/1
OUT(1)
DATA1
IN(1)
DATA1
IN(1)
DATA1
Figure 20.4 Transfer Stages in Control Transfer