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ADSP-BF537 Blackfin Processor Hardware Reference
8-15
Ethernet MAC
The frame filter is evaluated in the following sequence. Note that the
frame filter is updated as each byte of data is received. The frame filter can
change from true to false during a frame, for example, upon DMA over-
run, but can never change from false back to true.
1. Initially, the frame filter is set to true if the address filter is true,
otherwise the frame filter is set to false.
2.
PCF (pass control frames)
– If the
PCF
bit is 0 and the frame is any
valid supported MAC control frame (destination address is either
the MAC address or the global multicast pause address; and the
length/type field = 88-08, opcode = 0001, length = 64 bytes, and
receiveOK = 1), then the frame filter is set to false.
3.
PBF (pass bad frames)
– If the
PBF
bit is 0 and the frame has any
type of error except a frame fragment error, the frame filter is set to
false. This rejects any frame for which any of these status bits are
set: frame too long, alignment error, frame-CRC error, length
error, or unsupported control frame. The frame filter does not
reject frames on the basis of the out of range length field status bit.
Note that this step may reject MAC control frames passed by
PCF
.
4.
PSF (pass short frames)
– If the
PSF
bit is 0 and the frame has a
frame fragment error (frame contains less than 64 bytes), the frame
filter is set to false. This step may reject frames which were passed
by
PCF
or
PBF
.
5.
DMA RX overrun
– If the RX DMA FIFO overflows, the frame
filter is set to false. If the FIFO overflows at a point where it con-
tains parts of two frames, that is, the last data and status of frame A
and the beginning data of frame B, then frame B is rejected by the
frame filter and the MAC continues to try to deliver frame A’s data
and status.
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
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 ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
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 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
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 ...