Texas Instruments TMS320DM646x 사용자 설명서
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5.24 Receive Maximum Length Register (RXMAXLEN)
5.25 Receive Buffer Offset Register (RXBUFFEROFFSET)
Ethernet Media Access Controller (EMAC) Registers
The receive maximum length register (RXMAXLEN) is shown in
and described in
Figure 64. Receive Maximum Length Register (RXMAXLEN)
31
16
Reserved
R-0
15
0
RXMAXLEN
R/W-1518
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 63. Receive Maximum Length Register (RXMAXLEN) Field Descriptions
Bit
Field
Value
Description
31-16
Reserved
0
Reserved
15-0
RXMAXLEN
0-FFFFh
Receive maximum frame length. These bits determine the maximum length of a received frame.
The reset value is 5EEh (1518). Frames with byte counts greater than RXMAXLEN are long
frames. Long frames with no errors are oversized frames. Long frames with CRC, code, or
alignment error are jabber frames.
The reset value is 5EEh (1518). Frames with byte counts greater than RXMAXLEN are long
frames. Long frames with no errors are oversized frames. Long frames with CRC, code, or
alignment error are jabber frames.
The receive buffer offset register (RXBUFFEROFFSET) is shown in
and described in
Figure 65. Receive Buffer Offset Register (RXBUFFEROFFSET)
31
16
Reserved
R-0
15
0
RXBUFFEROFFSET
R/W-0
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 64. Receive Buffer Offset Register (RXBUFFEROFFSET) Field Descriptions
Bit
Field
Value
Description
31-16
Reserved
0
Reserved
15-0
RXBUFFEROFFSET
0-FFFFh
Receive buffer offset value. These bits are written by the EMAC into each frame SOP
buffer descriptor Buffer Offset field. The frame data begins after the RXBUFFEROFFSET
value of bytes. A value of 0 indicates that there are no unused bytes at the beginning of
the data, and that valid data begins on the first byte of the buffer. A value of Fh (15)
indicates that the first 15 bytes of the buffer are to be ignored by the EMAC and that valid
buffer data starts on byte 16 of the buffer. This value is used for all channels.
buffer descriptor Buffer Offset field. The frame data begins after the RXBUFFEROFFSET
value of bytes. A value of 0 indicates that there are no unused bytes at the beginning of
the data, and that valid data begins on the first byte of the buffer. A value of Fh (15)
indicates that the first 15 bytes of the buffer are to be ignored by the EMAC and that valid
buffer data starts on byte 16 of the buffer. This value is used for all channels.
SPRUEQ6 – December 2007
Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)
107