8101 datasheet(56/172 Pages) LSI

56 / 172 page

2-38

Functional Description

2.14.2 Append Options

The status word is normally appended to the end of all good receive

packets. However, the controller can also be programmed to store a

status word in the receive FIFO for discarded packets as well as append

a status word to the end of good (nondiscarded) packets. The controller

can also be programmed to not append any status word at all. Setting

the STSWRD [1:0] bits in “Register 7–Conﬁguration 1‚" Section 4.3.8,

select the appropriate status word option.

2.14.3 Status Word for Discarded Packets

When the controller is programmed to add a status word for discarded

packets, only the status word is stored in the receive FIFO for each

discarded packet. The status word for a discarded packet contains an

indication of the error that caused the discard. If the receive FIFO is full

and more than one consecutive packet was discarded, then one more

status word is stored in the receive FIFO for the next consecutive group

of discarded packets. A bit is set in the status word indicating that

multiple status words or multiple packets have been discarded. When a

status word has the multiple discard bit set, the other status bits reﬂect

the status of the second discarded packet only.

2.14.4 Status Word for RXABORT Packets

When the RXABORT pin is asserted, both the packet data and its

associated status word are normally ﬂushed from the receive FIFO.

Setting the RXAB_DEF bit in “Register 9–Conﬁguration 3‚"

Section 4.3.10, programs the controller to allow the RXABORT pin to

discard the packet only and leave the status word for the discarded

packet in the receive FIFO.

OSIZE

Oversize packet

1 = Receive packet is greater than maximum size RXD3

USIZE

Undersize packet 1 = Receive packet is less than minimum size

RXD2

OVFL

Receive FIFO

overﬂow

1 = Receive FIFO is full and has received

additional data

RXD1

CRC

CRC error

1 = Receive packet has a CRC error

RXD0

1. This byte order is for little endian format. Big endian format reverses this byte order.

Symbol

Name

Deﬁnition

Position on

RXD[31:0]1

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