Datasheet

515
32117D–AVR-01/12
AT32UC3C
24.7.5 Receive Buffer Queue Pointer Register
Name: RBQP
Access Type: Read/Write
Offset: 0x18
Reset Value: 0x00000000
This register points to the entry in the receive buffer queue (descriptor list) currently being used. It is written with the start
location of the receive buffer descriptor list. The lower order bits increment as buffers are used up and wrap to their original
values after either 1024 buffers or when the wrap bit of the entry is set.
Reading this register returns the location of the descriptor currently being accessed. This value is incremented as buffers
are used. User should not use this register to determine where to remove received frames from the queue as it constantly
changes when new frames are received. User should instead use the buffer descriptor queue checking the used bits.
Receive buffer writes can be bursts of two words and, as with transmit buffer reads, it is recommended that bit 2 is always
written to zero to prevent a burst crossing a 1K boundary, in violation of the System Bus specification.
• ADDR: Receive Buffer Queue Pointer Address
Write this field to set the start address of the receive queue.
Read this field to get the address of the current buffer being used.
31 30 29 28 27 26 25 24
ADDR[29:22]
23 22 21 20 19 18 17 16
ADDR[21:14]
15 14 13 12 11 10 9 8
ADDR[13:6]
76543210
ADDR[5:0] - -