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NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 23: LAN100 — Ethernet Media Access Controller
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
23-702
word contains ags returned by the LAN100 and ags generated by the Transmit
Datapath reecting the status of the transmission.
Table 11 lists the bit denitions in
the StatusInfo word.
For multi-fragment packets, the value of the LateCollision, ExcessiveCollision,
ExcessiveDefer, Defer and CollissionCount bits in all but the last fragment in the
packet will be 0. The status of the last fragment in the packet will copy the value for
these bits from the MII Interface. All fragment statuses will have valid Error,
NoDescriptor and Underrun bits.
5.
LAN100 Functions
This section denes the functions of the LAN100. After introducing the DMA concepts
and giving a description of the basic transmit and receive functions, this section
covers such advanced features as ow control, receive ltering, and the like.
5.1 MMIO Interface
5.1.1
Overview
The LAN100 MMIO interface is connected to the DCS system control bus so that the
host registers are visible from the CPU. The MMIO interface allows device driver
software on the CPU to interact with the LAN100.
The MMIO interface has a 32-bit datapath and an address aperture of 4KB. It only
Table 11: Transmit Status Information Word
Bit
Name
Function
31
Error
An error occurred during transmission. This is a logic OR of
LateCollision, ExcessiveCollision and ExcessiveDefer.
30
NoDescriptor
The Tx stream is interrupted, because a descriptor is not
available.
29
Underrun
A Tx underrun occurred because the adapter did not produce
transmit data or the adapter is not accepting statuses.
28
LateCollision
An Out-of-window-collision was seen, causing packet abort.
(See TSV[29].)
27
ExcessiveCollision Indicates this packet exceeded the maximum collision limit and
was aborted. (See TSV[28].)
26
ExcessiveDefer
This packet incurred deferral beyond the maximum deferral limit
and was aborted. (See TSV[27].)
25
Defer
This packet incurred deferral, because the medium was
occupied. This is not an error unless excessive deferral occurs.
(See TSV[26].)
24:21 CollisionCount
The number of collisions this packet incurred, up to the
Retransmission Maximum. (See TSV[19:16].)
20:0
-
Unused