Description of Operation
8-28
ADSP-BF537 Blackfin Processor Hardware Reference
In all cases, the TX DMA length word specifies the number of bytes to be
transfered via DMA, excluding the TX DMA length word itself. Specifi-
cally, when
TXDWA
is set, the TX DMA length word includes the length of
the two pad bytes. See
Late Collisions
If a frame’s transmission is interrupted (for example, by a late collision)
after the transmission of the first 64 bytes, the MAC can be programmed
to either automatically retry the frame or to discard the frame. If the
LCRTE
bit in the MAC operating mode register is set, the MAC issues a restart
command to the TX DMA channel and resets the DMA current address
pointer to the start of the current DMA descriptor. This requires the
frame data to be entirely contained in a single DMA descriptor.
Figure 8-9. TX DMA Data Alignment
1
0
PAD BYTE
EVEN WORD ALIGNMENT, TXDWA = 1
PAD BYTE
DMA-LENGTH WORD
3
2
DATA BYTE D
DATA BYTE C
DATA BYTE B
DATA BYTE A
5
4
DATA BYTE H
DATA BYTE G
DATA BYTE F
DATA BYTE E
1
0
DATA BYTE B
ODD WORD ALIGNMENT, TXDWA = 0
DATA BYTE A
DMA-LENGTH WORD
3
2
DATA BYTE F
DATA BYTE E
DATA BYTE D
DATA BYTE C
5
4
DATA BYTE J
DATA BYTE I
DATA BYTE H
DATA BYTE G
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...