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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
121 of 808
NXP Semiconductors
UM10360
Chapter 10: LPC17xx Ethernet
11.2 MAC Configuration Register 2 (MAC2 - 0x5000 0004)
The MAC configuration register 2 (MAC2) has an address of 0x5000 0004. Its bit
definition is shown in
.
13:12
-
Reserved. User software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
0x0
14
SIMULATION RESET
Setting this bit will cause a reset to the random number generator within the
Transmit Function.
0
15
SOFT RESET
Setting this bit will put all modules within the MAC in reset except the Host
Interface.
1
31:16
-
Reserved. User software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
0x0
Table 107. MAC Configuration register 1 (MAC1 - address 0x5000 0000) bit description
Bit
Symbol
Function
Reset
value
Table 108. MAC Configuration register 2 (MAC2 - address 0x5000 0004) bit description
Bit
Symbol
Function
Reset
value
0
FULL-DUPLEX
When enabled (set to ’1’), the MAC operates in Full-Duplex mode. When disabled,
the MAC operates in Half-Duplex mode.
0
1
FRAME LENGTH
CHECKING
When enabled (set to ’1’), both transmit and receive frame lengths are compared to
the Length/Type field. If the Length/Type field represents a length then the check is
performed. Mismatches are reported in the StatusInfo word for each received frame.
0
2
HUGE FRAME
ENABLE
When enabled (set to ’1’), frames of any length are transmitted and received.
0
3
DELAYED CRC
This bit determines the number of bytes, if any, of proprietary header information
that exist on the front of IEEE 802.3 frames. When 1, four bytes of header (ignored
by the CRC function) are added. When 0, there is no proprietary header.
0
4
CRC ENABLE
Set this bit to append a CRC to every frame whether padding was required or not.
Must be set if PAD/CRC ENABLE is set. Clear this bit if frames presented to the
MAC contain a CRC.
0
5
PAD / CRC ENABLE
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 PAD
ENABLE and VLAN PAD ENABLE. See
- Pad Operation for details on
the pad function.
0
6
VLAN PAD ENABLE
Set this bit to cause the MAC to pad all short frames to 64 bytes and append a valid
CRC. Consult
- Pad Operation for more information on the various
padding features.
Note:
This bit is ignored if PAD / CRC ENABLE is cleared.
0
7
AUTO DETECT PAD
ENABLE
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.
provides a description of the pad function based on the configuration of this register.
Note:
This bit is ignored if PAD / CRC ENABLE is cleared.
0
8
PURE PREAMBLE
ENFORCEMENT
When enabled (set to ’1’), the MAC will verify the content of the preamble to ensure
it contains 0x55 and is error-free. A packet with an incorrect preamble is discarded.
When disabled, no preamble checking is performed.
0
9
LONG PREAMBLE
ENFORCEMENT
When enabled (set to ’1’), the MAC only allows receive packets which contain
preamble fields less than 12 bytes in length. When disabled, the MAC allows any
length preamble as per the Standard.
0