NEC uPD98502 Buffer Direc tory

CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 345
6.6.2 Rx Buffer configuration
Data received from the USB is stored into a receive pool in system memory.
USB Controller uses three receive pools. The configuration of the receive pools is shown below.
Figure 6-13. Receive Buffer Configuration
Buffer desc riptor
Buffer desc riptor
Buffer desc riptor
Data
Buffer
Data
Buffer
Data
Buffer
Link pointer
Buffer desc riptor
Data
Buffer
Data
Buffer
Buffer desc riptor
Buffer Direc tory
Link pointer
Size
1-64k Bytes
Buffer desc riptor Data
Buffer
The receive buffer is composed of the Buffer Directory and Data Buffer. The receive buffer is prepared in system
memory by the VR4120A.
The formats of the Buffer Directory, Buffer descriptor, and Link Pointer are each described below.