Original Buffer Information Word 1 (Original Buffer Pointer)
Original Buffer Information Word 0 (Original Buffer Length)
Linking Information (Next Descriptor Pointer)
Buffer Information Word 1 (Buffer Pointer)
Buffer Information Word 0 (Buffer Length)
Word 2 [Pkt Info] Reserved
Word 1 (Reserved)
Word 0 (Reserved)
Required Information
(32 Bytes)
Word 2 [Buffer Info]
Architecture
1654
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
Figure 34-17. Host Buffer Descriptor Layout
Table 34-16. Host Buffer Descriptor Word 0 (HBD Word 0)
Bits
Name
Description
31-0
Reserved
Reserved
Table 34-17. Host Buffer Descriptor Word 1 (HBD Word 1)
Bits
Name
Description
31-0
Reserved
Reserved
Table 34-18. Host Buffer Descriptor Word 2 (HBD Word 2)
Bits
Name
Description
31-15
Reserved
Reserved
14
On-chip
This field indicates whether or not this descriptor is in a region which is in on-chip
memory space (1) or in external memory (0).
13-12
Packet Return Queue Mgr #
This field indicates which queue manager in the system the descriptor is to be
returned to after transmission is complete. This field is not altered by the DMA during
transmission or reception and is initialized by the CPU. There is only 1 Queue
Manager in the USB HS/FS Device Controller, this field must always be 0.
11-0
Packet Return Queue #
This field indicates the queue number within the selected queue manager that the
descriptor is to be returned to after transmission is complete. This field is not altered
by the DMA during transmission or reception and is initialized by the CPU.
Table 34-19. Host Buffer Descriptor Word 3 (HBD Word 3)
Bits
Name
Description
31-22
Reserved
Reserved
21-0
Buffer 0 Length
The Buffer Length field indicates how many valid data bytes are in the buffer. The
CPU initializes this field for transmitted packets; the DMA overwrites this field on
packet reception.