Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 907

Table 15-163. Transmit Data Buffer Descriptor (TxBD) Field Descriptions (continued)
Offset Bits Name
0–1 5 TC
6 PRE
DEF
7 —
8 HFE
LC
9 CF
RL
10–13 RC
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
Freescale Semiconductor
Tx CRC. Written by user. (Valid only while it is set in first BD and TxBD[PAD/CRC] is cleared and
MACCFG2[PAD/CRC enable] is cleared and MACCFG2[CRC enable] is cleared.) If
MACCFG2[PAD/CRC enable] is set or MACCFG2[CRC enable] is set, this bit is ignored in
ethernet modes.0End transmission immediately after the last data byte with no hardware
generated CRC appended, unless TxBD[PAD/CRC] is set.
1 Transmit the CRC sequence after the last data byte.
Transmit user-defined Ethernet preamble. Written by user. Valid only if set in the first BD of a frame,
and MACCFG2[PreAm TxEN] is set.
0 This frame does not contain Ethernet preamble bytes for transmission.
1 This frame includes a user-defined Ethernet preamble sequence prior to the destination address
in the data buffer.
Defer indication. The eTSEC updates this bit after transmitting a frame (TxBD[L] is set)
0 This frame was not deferred.
1 This frame did not have a collision before it was sent but it was sent late because of deferring
Reserved
Huge frame enable. Written by user. Valid only if set in the first BD of a frame and MACCFG2[Huge
Frame] is cleared. If MACCFG2[Huge Frame] is set, this bit is ignored.
0 Truncate transmit frame if its length is greater than the MAC's maximum frame length.
1 Allow large frames to be transmitted without truncation.
Late collision. Written by the eTSEC.
0 No late collision.
1 A collision occurred after 64 bytes are sent. The eTSEC terminates the transmission and
updates LC.
Control Frame. Written by user. Valid only if set in the first BD of a frame.
0 Regular frame; transmission is deferred when eTSEC is in PAUSE.
1 Control frame; transmission starts even if eTSEC is in PAUSE.
Retransmission Limit. Written by the eTSEC.
0 Transmission before maximum retry limit is hit.
1 The transmitter failed (max. retry limit + 1) attempts to successfully send a message due to
repeated collisions. The eTSEC terminates the transmission and updates RL.
Retry Count. Written by the eTSEC.
0 The frame is sent correctly the first time.
x One or more attempts where needed to send the transmit frame. If this field is 15, then 15 or
more retries were needed. The Ethernet controller updates RC after sending the buffer.
Enhanced Three-Speed Ethernet Controllers
Description
15-189