![background image](http://html1.mh-extra.com/html/national-semiconductor/macphyter-ii-dp83816/macphyter-ii-dp83816_manual_3402840079.webp)
78
www.national.com
5.0 Buffer Management
(Continued)
DP83816
Table 5-3 Transmit Status Bit Definitions
27
OK
Packet OK
In the last descriptor in a packet, this bit indicates that the packet
was either sent or received successfully.
26-16
---
The usage of these bits differ in receive and transmit descriptors.
See below for details.
15-12
(reserved)
11-0
SIZE
Descriptor Byte Count Set to the size in bytes of the data.
Bit
Tag
Description
Usage
26
TXA
Transmit Abort
Transmission of this packet was aborted.
25
TFU
Transmit FIFO
Underrun
Transmit FIFO was exhausted during the transmission of this
packet.
24
CRS
Carrier Sense Lost
Carrier was lost during the transmission of this packet. This
condition is not reported if TXCFG:CSI is set.
23
TD
Transmit Deferred
Transmission of this packet was deferred.
22
ED
Excessive Deferral
The length of deferral during the transmission of this packet was
excessive (> 3.2 ms), indicating transmission failure.
21
OWC
Out of Window
Collision
The MAC encountered an "out of window" collision during the
transmission of this packet.
20
EC
Excessive Collisions
The number of collisions during the transmission of this packet
was excessive, indicating transmission failure.
If TXCFG register ECRETRY=0, this bit is set after 16 collisions.
If TXCFG register ECRETRY=1, this bit is set after 4 Excessive
Collision events (64 collisions).
19-16
CCNT
Collision Count
If TXCFG register ECRETRY=0, this field indicates the number of
collisions encountered during the transmission of this packet.
If TXCFG register ECRETRY=1,
CCNT[3:2] = Excessive Collisions (0-3)
CCNT[1] = Multiple Collisions
CCNT[0] = Single Collision
Note that Excessive Collisions indicate 16 attempts failed, while
multiple and single collisions indicate collisions in addition to any
excessive collisions. For example a collision count of 33 includes
2 Excessive Collisions and will also set the Single Collision bit.
Summary of Contents for MacPHYTER-II DP83816
Page 106: ...105 www national com DP83816 Notes...