The Transmit VLAN Tag (TTAG) register is shown in the following figure. This register is only used when the VLAN tagging is included in the subsystem at build-time (C_TXVLAN_TAG = 1). When a VLAN tag is added to a transmit frame, this is the value that is added to the frame right after the source address field. See Extended VLAN Support for more information about how VLAN tagging is performed.
Figure 1. Transmit VLAN Tag Register (0x0000_0018)
The following table shows the Transmit VLAN Tag register bit definitions.
Bits | Name | Access | Reset Value | Description |
---|---|---|---|---|
31:16 | TPID | R/W | 0x0 | Tag Protocol Identifier. |
15:13 | Priority | R/W | 0x0 | User Priority. |
12 | CFI | R/W | 0 | Canonical Format Indicator. |
11:0 | VID | R/W | 0x0 | VLAN identifier:Uniquely identifies the VLAN to which the frame belongs. |