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Table 4-4. BDT Data Used by USB Controller and Microprocessor
USB Controller Determines… Microprocessor Determines…
Who owns the buffer in system memory Who owns the buffer in system memory
Data0 or Data1 PID Data0 or Data1 PID
Release Own upon packet completion
No address increment (FIFO Mode)
Data Toggle Synchronization enable
Amount of data to be transmitted or received Amount of data transmitted or received
Where the buffer resides in system memory Where the buffer resides in system memory
Table 4-5 shows the USB BD format.
Table 4-5. USB Buffer Descriptor Format
7 6 5 4 3 2 1 0
OWN DATA0/1 USB_OWN NINC DTS RSVD 0 0
0
BC[7:0]
0 BCH9 BCH8
Low Byte ADDR[7:0]
Byte 2 ADDR[15:8]
Byte 3 ADDR[23:16]
Byte 4 ADDR[31:24]