Fujitsu F2MC-16LX Hardware Manual page 289

[bit 3, bit 2] Reserved bit
It is reserved bit. Please write "0". The bit always reads "0".
[bit 1] RFBK: Data toggle mode selection bit (rate feedback mode)
It is a bit that selects data toggle mode for USB Interrupt transfer.
RFBK
0 Selection of alternation data toggle mode
It toggles a data PID when a transfer has been successfully completed.
1 Selection of data toggle mode
It is a toggle the data PID in unconditional.
The data toggle mode selection can be used for rate feedback information in ISO transfer.
[bit 0] PWC: Power supply control bit
It specifies the operating power supply mode (self power or bus power) for the USB Function.
(The setting of the PWC bit is reflected in the standard command GetStatus.)
PWC
0 Bus power
1 Self power
CHAPTER 13 USB FUNCTION
Operating mode
Operating mode
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