E F E c o n f i g u r a t i o n

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

 

D07

R/W

AUTOP

0

Auto detect pad enable

 

 

 

 

When set to 1, the MAC automatically detects the

 

 

 

 

frame type — tagged or untagged — by comparing

 

 

 

 

the two octets following the source address with

 

 

 

 

’h8100 VLAN protocol ID and pad accordingly. See

 

 

 

 

Table 62: "PAD operation" on page 183 for

 

 

 

 

additional information.

 

 

 

 

Note:

This bit is ignored if PADEN (D05) is set

 

 

 

 

 

to 0.

 

 

 

 

 

D06

R/W

VLANP

0

VLAN pad enable

 

 

 

 

When set to 1, the MAC pads all short frames to

 

 

 

 

64 bytes and appends a valid CRC.

 

 

 

 

See Table 62: "PAD operation" on page 183 for

 

 

 

 

additional information.

 

 

 

 

Note:

This bit is ignored if PADEN (D05) is set

 

 

 

 

 

to 0.

 

 

 

 

 

D05

R/W

PADEN

0

PAD/CRC enable

 

 

 

 

1 The MAC pads all short frames.

 

 

 

 

0 Frames presented to the MAC have a valid

 

 

 

 

length.

 

 

 

 

PADEN is used in conjunction with the Auto detect

 

 

 

 

pad enable and VLAN pad enable fields.

 

 

 

 

See Table 62: "PAD operation" on page 183 for

 

 

 

 

additional information.

 

 

 

 

 

D04

R/W

CRCEN

0

CRC enable

 

 

 

 

1 Appends a CRC to every frame whether or not

 

 

 

 

padding is required. This bit must be set to 1 if

 

 

 

 

PAD/CRC is enabled.

 

 

 

 

0 Indicates that frames presented to the MAC

 

 

 

 

already contain a CRC.

 

 

 

 

 

D03

R/W

DELCRC

0

Delayed CRC

 

 

 

 

Determines the number of bytes, if any, of

 

 

 

 

proprietary header information that exist in the

 

 

 

 

front of the IEEE 802.3 frames.

1 Four bytes of proprietary header information (ignored by the CRC calculation function).

0 Zero bytes of proprietary header information.

Table 61: MAC Configuration Register 2 bit definition

1 8 2

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

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Digi NS7520 manual Auto detect pad enable, Vlan pad enable, PAD/CRC enable, Delayed CRC