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NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 596 -
Revision V1.30
NUC97
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TXDES 2: TXDMA Descriptor Word 2
The TXDMA descriptor word 2 contains transmit frame status, and transmit frame byte count. The
detail description of TXDES 2 is shown below.
31
30
29
28
27
26
25
24
CCNT
TTSAS
SQE
PAU
TXHA
23
22
21
20
19
18
17
16
LC
TXABT
NCS
EXDEF
TXCP
Reserved
DEF
TXINTR
15
14
13
12
11
10
9
8
TBC
7
6
5
4
3
2
1
0
TBC
Bits
Description
[31:28]
CCNT
Collision Count
The CCNT indicates the how many collisions found consecutively during a packet
transmission. If the packet incurred 16 consecutive collisions during transmission, the
CCNT is 0x0 and bit TXABT is set high.
[27]
TTSAS
TX Time Stamp Active Status
This bit is to indicate the time stamping circuit stamped this frame successfully. When
this bit set high, TX Descriptor Word 1 and TX Descriptor Word 3 keep the time stamp
value recorded when SFD of frame is transmitted out on MII/RMII.
0 = TX Descriptor Word 1 and TX Descriptor Word 3 does not keep the time stamp value.
1 = TX Descriptor Word 1 and TX Descriptor Word 3 keep the time stamp value.
[26]
SQE
SQE Error
The SQE indicates the SQE error found at end of packet transmission on 10Mbps half-
duplex mode. The SQE error check will only be done while both bit EnSQE of MCMDR is
enabled and EMAC is operating on 10Mbps half-duplex mode.
0 = No SQE error found at end of packet transmission.
1 = SQE error found at end of packet transmission.
[25]
PAU
Transmission Paused
The PAU indicates the next normal packet transmission process will be paused
temporally because EMAC received a PAUSE control frame, or software sets the bit
SDPZ of MCMDR and enables EMAC to transmit a PAUSE control frame out.
0 = Next normal packet transmission process continue normally.
1 = Next normal packet transmission process paused.
[24]
TXHA
Transmission Halted
The TXHA indicates the next normal packet transmission process will be halted because
the bit TXON of MCMDR is disabled by software.
0 = Next normal packet transmission process continue normally.
1 = Next normal packet transmission process halted.