Datasheet

516
32117D–AVR-01/12
AT32UC3C
24.7.6 Transmit Buffer Queue Pointer Register
Name: TBQP
Access Type: Read/Write
Offset: 0x1C
Reset Value: 0x00000000
This register points to the entry in the transmit buffer queue (descriptor list) currently being used. It is written with the start
location of the transmit 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. This register can only be written when bit TSR.TGO
is low.
As transmit buffer reads can be bursts of two words, 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: Transmit buffer queue pointer address
Write this field to set the start address of the transmit queue.
Read this field to get the address of the first buffer of the frame being transmitted or about to be transmitted.
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] - -