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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
23-679
12
NO_BACKOFF
R/W
0
When set, the MAC will immediately retransmit following a collision
rather than using the Binary Exponential Backoff algorithm as
specied in the Standard
11:10
-
0
Unused
9
LONG_PREAMBLE_
ENFORCEMENT
R/W
0
When set, the MAC only allows receive packets which contain
preamble elds less than 12 bytes in length. When cleared, the
MAC allows any length preamble as per the Standard
8
PURE_PREAMBLE_
ENFORCEMENT
R/W
0
When set, the MAC will verify the content of the preamble to ensure
it contains 0x55 and is error-free. Packets with errors in the
preamble are discarded.
7
AUTO_DETECT_PAD_
ENABLE
R/W
0
Set this bit to cause the MAC to automatically detect the type of
frame, either tagged or un-tagged, by comparing the two octets
following the source address with 0x8100 (VLAN Protocol ID) and
pad accordingly. For more information refer to the MII Interface
documentation.
6
VLAN PAD ENABLE
R/W
0
Set this bit to cause the MAC to pad all short frames to 644 bytes
and append a valid CRC. For more information, refer to the MII
Interface documentation.
5
PAD_CRC_ENABLE
R/W
0
Set this bit to have the MAC pad all short frames. Clear this bit if
frames presented to the MAC have a valid length. This bit is used in
conjunction with AUTO_DETECT_PAD_ENABLE and VLAN_PAD_
ENABLE.
4
CRC_ENABLE
R/W
0
Set this bit to append a cyclic redundancy check (CRC) to every
frame, whether padding was required or not. This bit must be set if
PAD_CRC_ENABLE is set. Clear this bit if frames presented to the
MAC contain a CRC.
3
DELAYED_CRC
R/W
0
This bit determines the number of bytes, if any, of proprietary
header information that exist on the front of IEEE 802.3 frames. For
more information refer to the MII Interface documentation.
2
HUGE_FRAME_
ENABLE
R/W
0
When set, frames of any length can be transmitted and received.
1
FRAME_LENGTH_
CHECKING
R/W
0
When set, both transmit and receive frame lengths are compared to
the length/type eld. If the length/type eld represents a length,
then the check is performed. Mismatches are reported on the
Transmit/Receive Statistics Vector.
0
FULL_DUPLEX
R/W
0
When set, the MAC operates in full-duplex mode. Disable for
half-duplex operation.
Offset 0x07 2008
Back-to-Back Inter-Packet-Gap Register (IPGT)
31:7
-
0
Unused
Table 2: LAN100 Registers …Continued
Bit
Symbol
Acces
s
Value
Description