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Table 20-2. Enhanced Transmit Descriptor 0 (TDES0) (continued)
Description
Bit
VLIC: VLAN Insertion Control
When set, these bits request the MAC to perform VLAN tagging or untagging before transmitting the frames. If
the frame is modified for VLAN tags, the MAC automatically recalculates and replaces the CRC bytes.
The values of this field are as follows:
■
0x0= Do not add a VLAN tag
■
0x1= Remove the VLAN tag from the frames before transmission.
■
0x2= Insert a VLAN tag with the tag value programmed in the
Ethernet MAC VLAN Tag Inclusion or
Replacement (EMACVLNINCREP)
register, offset 0x584.
■
0x3= Replace the VLAN tag in frame with the tag value programmed in the
EMACVLNINCREP
register. This
field is valid when the First Segment control bit (TDES0[28]) is set.
19:18
TTSS:TX Timestamp
This status bit indicates that a timestamp has been captured for the corresponding transmit frame. When this bit
is set, TDES6 and TDES7 have timestamp values that were captured for the transmit frame. This field is valid
only when the Last Segment control bit (TDES0[29]) in a descriptor is set.
17
IHE: IP Header Error
When set, this bit indicates that the Checksum Offload engine detected an IP header error. This bit is valid only
when TX Checksum Offload is enabled. Otherwise, it is reserved. If the Checksum Offload Engine detects an IP
header error, it still inserts an IPv4 header checksum if the Ethernet Type field indicates an IPv4 payload.
16
ES: Error Summary
Indicates the logical OR of the following bits:
■
TDES0[16]: IP Header Error
■
TDES0[14]: Jabber Timeout
■
TDES0[13]: Frame Flush
■
TDES0[12]: Payload Checksum Error
■
TDES0[11]: Loss of Carrier
■
TDES0[10]: No Carrier
■
TDES0[9]: Late Collision
■
TDES0[8]: Excessive Collision
■
TDES0[2]: Excessive Deferral
■
TDES0[1]: Underflow error
15
JT: Jabber Timeout
When set, this bit indicates that the MAC transmitter has experienced a jabber timeout. This bit can only be set
when the Jabber Disabled (
JD
) bit of the
EMACCFG
register is clear.
14
FF: Frame Flushed
When set, this bit indicates that the DMA flushed the frame because of a software flush command given by the
CPU.
13
IPE: IP Payload Error
When set, this bit indicates that MAC transmitter detected an error in the TCP, UDP, or ICMP IP datagram
payload. The transmitter checks the payload length received in the IPv4 or IPv6 header against the actual number
of TCP, UDP, or ICMP packet bytes received from the application and issues an error status in case of a mismatch.
12
June 18, 2014
1416
Texas Instruments-Production Data
Ethernet Controller