Section 23 Gigabit Ethernet Controller (GETHER)
Rev. 1.00 Oct. 01, 2007 Page 945 of 1956
REJ09B0256-0100
When one transmit frame is divided into three parts or more with transmit descriptors, the E-
DMAC performs the following write-back operation:
•
A write-back operation is performed for a transmit descriptor including information for the
start of the transmit frame (TFP = 10 or 11) and for a transmit descriptor including information
for the end of the frame (TFP = 01 or 11).
•
A write-back operation is not performed for a transmit descriptor for the middle of the frame
(TFP = 00).
However, TFE (transmit frame error occurrence) or TFS (transmit frame status) is written only to
a transmit descriptor including information for the end of the frame (TFP = 01 or 11) by a write-
back operation.
Before changing a transmit descriptor with the software, make sure that a write-back operation has
been performed (TACT = 0) for the transmit descriptor including information for the end of the
frame (TFP = 01 or 11) to avoid overwriting (re-setting) an unprocessed transmit descriptor.
(2) Receive
Descriptor
Figure 23.4 shows the relationship between a receive descriptor and receive buffer.
The data of a receive descriptor consists of RD0, RD1, RD2, and padding data in groups of 32 bits
from top to end. The length of padding data is determined according to the descriptor length
specified by the DL0 and DL1 bits in EDMR.
RD0 indicates whether the receive descriptor is valid or invalid, and information about descriptor
configuration and status. RD1 indicates the length of data that can be received in the receive buffer
specified by the descriptor (RBL) and the length of the received frame data (RDL). RD2 indicates
the start address of the receive buffer for storing receive data (RBA).
Depending on the descriptor specification, one receive descriptor can specify the storing of all
receive data of one frame in a receive buffer (single-frame/single-buffer) or multiple descriptors
can specify the storing of the receive data of one frame in receive buffers (single-frame/multi-
buffer). As an example of single-frame/multi-buffer operation, suppose that a row of multiple
descriptors (descriptor list) is prepared, RBL of each descriptor is 500 bytes, and a 1514-byte
Ethernet frame is received. In such a case, the received Ethernet frame is transferred sequentially
to buffers, 500 bytes for each buffer, starting with the first descriptor. Only the last 14 bytes are
transferred to the fourth buffer. When a frame longer than RBL of a descriptor is received, the E-
DMAC transfers the remaining data to the receive buffer by using the subsequent descriptors. As
an example of efficient single-frame/multi-buffer operation, information items on different
processing layers in an Ethernet frame can be separated from each other by using different buffers.
For example, the destination address, transmit source address, and type field data in an Ethernet
Содержание SH7763
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Страница 122: ...Section 2 Programming Model Rev 1 00 Oct 01 2007 Page 56 of 1956 REJ09B0256 0100 ...
Страница 144: ...Section 3 Instruction Set Rev 1 00 Oct 01 2007 Page 78 of 1956 REJ09B0256 0100 ...
Страница 170: ...Section 4 Pipelining Rev 1 00 Oct 01 2007 Page 104 of 1956 REJ09B0256 0100 ...
Страница 282: ...Section 7 Caches Rev 1 00 Oct 01 2007 Page 216 of 1956 REJ09B0256 0100 ...
Страница 378: ...Section 9 Interrupt Controller INTC Rev 1 00 Oct 01 2007 Page 312 of 1956 REJ09B0256 0100 ...
Страница 514: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Oct 01 2007 Page 448 of 1956 REJ09B0256 0100 ...
Страница 630: ...Section 13 PCI Controller PCIC Rev 1 00 Oct 01 2007 Page 564 of 1956 REJ09B0256 0100 ...
Страница 686: ...Section 14 Direct Memory Access Controller DMAC Rev 1 00 Oct 01 2007 Page 620 of 1956 REJ09B0256 0100 ...
Страница 710: ...Section 16 Clock Pulse Generator CPG Rev 1 00 Oct 01 2007 Page 644 of 1956 REJ09B0256 0100 ...
Страница 732: ...Section 17 Watchdog Timer and Reset WDT Rev 1 00 Oct 01 2007 Page 666 of 1956 REJ09B0256 0100 ...
Страница 752: ...Section 18 Power Down Mode Rev 1 00 Oct 01 2007 Page 686 of 1956 REJ09B0256 0100 ...
Страница 772: ...Section 19 Timer Unit TMU Rev 1 00 Oct 01 2007 Page 706 of 1956 REJ09B0256 0100 ...
Страница 824: ...Section 21 Compare Match Timer CMT Rev 1 00 Oct 01 2007 Page 758 of 1956 REJ09B0256 0100 ...
Страница 1060: ...Section 23 Gigabit Ethernet Controller GETHER Rev 1 00 Oct 01 2007 Page 994 of 1956 REJ09B0256 0100 ...
Страница 1062: ...Section 24 IP Security Accelerator SECURITY Rev 1 00 Oct 01 2007 Page 996 of 1956 REJ09B0256 0100 ...
Страница 1124: ...Section 26 I 2 C Bus Interface IIC Rev 1 00 Oct 01 2007 Page 1058 of 1956 REJ09B0256 0100 ...
Страница 1184: ...Section 27 Serial Communication Interface with FIFO SCIF Rev 1 00 Oct 01 2007 Page 1118 of 1956 REJ09B0256 0100 ...
Страница 1350: ...Section 30 SIM Card Module SIM Rev 1 00 Oct 01 2007 Page 1284 of 1956 REJ09B0256 0100 ...
Страница 1484: ...Section 33 Audio Codec Interface HAC Rev 1 00 Oct 01 2007 Page 1418 of 1956 REJ09B0256 0100 ...
Страница 1560: ...Section 35 USB Host Controller USBH Rev 1 00 Oct 01 2007 Page 1494 of 1956 REJ09B0256 0100 ...
Страница 1720: ...Section 37 LCD Controller LCDC Rev 1 00 Oct 01 2007 Page 1654 of 1956 REJ09B0256 0100 ...
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