Register 8: Ethernet MAC VLAN Tag (EMACVLANTG), offset 0x01C
The Ethernet MAC VLAN Tag (MACVLANTG) register contains the IEEE 802.1Q VLAN Tag to
identify the VLAN frames. The MAC compares the 13th and 14th bytes of the receiving frame
(Length/Type) with the value 0x8100, and the following two bytes are compared with the VLAN tag.
If a match occurs, the MAC sets the received VLAN bit in the receive frame status. The legal length
of the frame is increased from 1,518 bytes to 1,522 bytes.
Ethernet MAC VLAN Tag (EMACVLANTG)
Base 0x400E.C000
Offset 0x01C
Type RW, reset 0x0000.0000
16171819202122232425262728293031
ETVVTIMESVLVTHMreserved
RWRWRWRWROROROROROROROROROROROROType
0000000000000000Reset
0123456789101112131415
VL
RWRWRWRWRWRWRWRWRWRWRWRWRWRWRWRWType
0000000000000000Reset
DescriptionResetTypeNameBit/Field
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0ROreserved31:20
VLAN Tag Hash Table Match Enable
DescriptionValue
The VLAN Hash Match operation is not performed.0
The most significant four bits of the VLAN tag's CRC are used
to index the content of the MAC VLAN Hash Table
(EMACVLANHASH) register. A value of 1 in the
EMACVLANHASH register, corresponding to the index,
indicates that the frame matched the VLAN hash table.
When Bit 16 (ETV) is set, the CRC of the 12-bit VLAN Identifier
(VID) is used for comparison whereas when ETV is reset, the
CRC of the 16-bit VLAN tag is used for comparison.
1
0RWVTHM19
Enable S-VLAN
DescriptionValue
The MAC transmitter does not recognize S-VLAN frames as
valid VLAN tagged frames.
0
The MAC transmitter and receiver considers the S-VLAN (Type
= 0x88A8) frames as valid VLAN tagged frames.
1
0RWESVL18
1489June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller
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