ADSP-BF537 Blackfin Processor Hardware Reference
8-19
Ethernet MAC
are truncated by the MAC. The 1556-byte hardware limit accommodates
the longest legal Ethernet frames (1518 bytes for untagged frames, or
1522 bytes for tagged 802.1Q frames) plus a small margin to accommo-
date future standards extensions.
The MAC does not support RX DMA data buffers composed of more
than one descriptor.
RX Frame Status Buffer
The RX frame status buffer is always an integer multiple of 32-bit words
in length (either 1 or 2) and must always be aligned on a 32-bit boundary.
The RX frame status buffer always contains a frame status word, and may
also contain two 16-bit IP checksum words if the
RXCKS
bit in the MAC
system control register is set.
To synchronize RX DMA and software, the
RX_COMP
semaphore bit may
be used in the RX frame status word. This word is always the last word
written via DMA in both status buffer formats, so a transition from 0 to 1
as seen by the processor always means that both the RX data and the status
buffers are entirely valid.
and
describe each of the status buffer formats.
Table 8-2. Receive Status DMA Buffer Format (Without IP Checksum)
Offset
Size
Description
0
32
RX frame status (Same format as the current RX frame
status register)
Table 8-3. Receive Status DMA Buffer Format (With IP
Checksum)
Offset
Size
Description
0
16
IP header checksum
Содержание Blackfin ADSP-BF537
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Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...