SNLS059E datasheet(82/110 Pages) TI2

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5.0 Buffer Management (Continued)

Table 5-4 Receive Status Bit Definitions

5.1.2 Single Descriptor Packets

To represent a packet in a single descriptor, the MORE bit in the cmdsts field is set to 0.

Figure 5-1 Single Descriptor Packets

Bit

Tag

Description

Usage

RXA

Receive Aborted

Set to 1 by DP83815 when the receive was aborted, the value of

this bit always equals RXO. Exists for backward compatibility.

RXO

Receive Overrun

Set to 1 by DP83815 to indicate that a receive overrun condition

occurred. RXA will also be set.

24-23

DEST

Destination Class

When the receive filter is enabled, these bits will indicate the

destination address class as follows:

00 - Packet was rejected

01 - Destination is a Unicast address

10 - Destination is a Multicast address

11 - Destination is a Broadcast address

If the Receive Filter is enabled, 00 indicates that the packet was

rejected. Normally packets that are rejected do not cause any bus

activity, nor do they consume receive descriptors. However, this

condition could occur if the packet is rejected by the Receive Filter

later in the packet than the receive drain threshold

(RXCFG:DRTH).

Note: The DEST bits may not represent a correct DA class for runt

packets received with less than 6 bytes.

LONG

Too Long Packet

Received

If RXCFG:ALP=0, this flag indicates that the size of the receive

packet exceeded 1518 bytes.

If RXCFG:ALP=1, this flag indicates that the size of the receive

packet exceeded 2046 bytes.

RUNT

Runt Packet Received The size of the receive packet was less than 64 bytes (inc. CRC).

ISE

Invalid Symbol Error

(100 Mb/s only) An invalid symbol was encountered during the

reception of this packet.

CRCE

CRC Error

The CRC appended to the end of this packet was invalid.

FAE

Frame Alignment Error The packet did not contain an integral number of octets.

LBP

Loopback Packet

The packet is the result of a loopback transmission.

COL

Collision Activity

The receive packet had a collision during reception.

link

ptr

MAC hdr

netwk hdr

data

single descriptor / single fragment

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