CHAPTER 12 USB FUNCTION CONTROLLER (USBF)
Preliminary User’s Manual U19014EJ1V0UD
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(3) CPUDEC request for control transfer
The CPUDEC request can be classified into three types of processing: control transfer (write), control transfer
(read), and control transfer (without data). Control transfer (write) indicates a request that uses the OUT
transaction in the data stage (e.g., SET_DESCRIPTOR), and control transfer (read) indicates a request that
uses the IN transaction in the data stage (e.g., GET_DESCRIPTOR). Control transfer (without data) indicates
a request that has no data stage (e.g., SET_CONFIGURATION).
The flowcharts are shown below.
Figure 12-19. CPUDEC Request for Control Transfer (1/12)
(a) Token phase (1/2)
START
CPUDEC = 1?
(UF0IS1)
INTUSB0B
active
Appropriate interrupt servicing
CPUDEC = 0
(UF0IS1)
Reading UF0ISn register
PROTC = 0
(UF0IC1)
STGM = 0 (UF0IM1)
CPUDECM = 1 (UF0IM1)
Reading UF0E0ST
register
×
8 times
Decoding FW request
Yes
No
G
E
A
Remarks 1.
n = 0, 1
2.
♦
: Processing by hardware
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