9-28
DS785UM1
Copyright 2007 Cirrus Logic
1/10/100 Mbps Ethernet LAN Controller
EP93xx User’s Guide
9
9
9
Figure 9-14. Multiple Fragments Per Transmit Frame
, one frame is transmitted from three fragments. The
MAC starts the frame by acquiring the medium and transmitting the preamble. Then, the
fragments 0, 1, 2 are transmitted in order for a total of 446 bytes (39 + 388 + 19). Since the
CRC bit in the first frame fragment is clear, the HW appends the 4 byte CRC. Thus, 4 more
bytes are added to the frame for the CRC making the total frame length 450 bytes. Finally, the
MAC sends the end-of-frame.
The CMD field is 4 bits. Only the AF bit is valid. The other fields are reserved.
9.2.3.9 Transmit Descriptor Format
Transmit Descriptor Format - First Word
Definition:
Transmit Descriptor, first word. Contains the base address of the data buffer.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
TBA
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
TBA
register sizes are in bits,
and shown in parentheses ().
T x B u fA d r 0 ( 3 2 )
T x D B u f A d r 1 ( 3 2 )
T x D B u f A d r 2 ( 3 2 )
Data Fragment 0
Fragment 0
Length
89 bytes
Example: Fragments 0, 1, 2 make-up one complete frame.
Data Fragment 1
Fragment 1
Length
388 bytes
Data Fragment 2
Fragment 2
Length
19 bytes
EOF = 0
EOF = 0
EOF = 1
Buffer
Length 0 (12)
Buffer
Length 0 (12)
Buffer
Length 0 (12)
CMD
(4)
CMD
(4)
CMD
(4)
Buffer
Index 0 (15)
Buffer
Index 0 (15)
Buffer
Index 0 (15)
EOF
EOF
EOF
Summary of Contents for EP93 Series
Page 28: ...P 6 DS785UM1 Copyright 2007 Cirrus Logic Preface EP93xx User s Guide PP P ...
Page 162: ...5 36 DS785UM1 Copyright 2007 Cirrus Logic System Controller EP93xx User s Guide 55 5 ...
Page 576: ...15 18 DS785UM1 Copyright 2007 Cirrus Logic UART2 EP93xx User s Guide 1515 15 ...
Page 634: ...17 38 DS785UM1 Copyright 2007 Cirrus Logic IrDA EP93xx User s Guide 1717 17 ...
Page 648: ...19 6 DS785UM1 Copyright 2007 Cirrus Logic Watchdog Timer EP93xx User s Guide 1919 19 ...
Page 688: ...21 32 DS785UM1 Copyright 2007 Cirrus Logic I2S Controller EP93xx User s Guide 2121 21 ...
Page 790: ...27 20 DS785UM1 Copyright 2007 Cirrus Logic IDE Interface EP93xx User s Guide 2727 27 ...
Page 808: ...28 18 DS785UM1 Copyright 2007 Cirrus Logic GPIO Interface EP93xx User s Guide 2828 28 ...