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CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S14767EJ1V0UM00
425
Figure 6-14. Receive Descriptor Configuration
-Rx Buffer Directory
Buffer Directory
-Rx Link Pointer
0
3
0
|
Buffer Desciptor
Buffer Desciptor
Buffer Desciptor
Buffer Desciptor
Buffer Desciptor
Buffer Desciptor
Link
-Rx Buffer Descriptor
3
0
16
Buffer
Reserve
Siz
-Rx Pool Descriptor
3
0
16
Buffer Directory
Reserve
RNOD
L
1
3
Reserve
2
0
3
0
16
3
2
Aler
0
3
2
2
Rx Pool Descriptor:
Contains the receive pool data.
The "Buffer Directory Number" field indicates the remaining Buffer Directory number.
When USB Controller uses a new Buffer Directory upon receiving data, USB Controller
decrements this field by one.
After decrementing the value in RNOD field, if decremented value becomes equal to the
value 4 times of Alert filed USB Controller sets Bit16 (Pool0) or Bit17 (Pool1) or Bit18
(Pool2) in USB General Status Register1 to one. If not masked, USB Controller
generates interrupt to V
R
4120A RISC Processor.
Once decrementing causes this field to reach 0, USB Controller makes Bit19 (Pool0) or
Bit20 (Pool1) or Bit21 (Pool2) of the General Status Register1 active provided it is not
masked, issues an interrupt to the V
R
4120A RISC Processor. The "Buffer Directory
Address" field indicates the start address of the receive Buffer Directory.
A receive Buffer Directory. This is configured of a buffer descriptor and a link pointer. A
single receive Buffer Directory can contain up to 255 buffer descriptors.
Contains the receive buffer data.
When Bit31 (Last bit) is active, that Buffer Descriptor indicates the last buffer in the pool.
Rx Buffer Directory:
Rx Buffer Descriptor: