LAN9250 datasheet(173/421 Pages) MICROCHIP

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DS00001913A-page 173

LAN9250

11.12.3

RX STATUS FORMAT

BITS

DESCRIPTION

Packet Filter.

When set, this bit indicates that the associated frame passed the frame filtering

described in Section 11.5.

Filtering Fail.

When set, this bit indicates that the associated frame failed the address recognizing fil-

tering described in Section 11.4.

29:16

Packet Length.

The size, in bytes, of the corresponding received frame.

Error Status (ES).

When set this bit indicates that the Host MAC Interface Layer (MIL) has reported an

error. This bit is the Internal logical “or” of bits 11,7,6 and 1.

Reserved.

These bits are reserved. Reads 0.

Broadcast Frame.

When set, this bit indicates that the received frame has a Broadcast address.

Length Error (LE).

When set, this bit indicates that the actual length does not match with the length/

type field of the received frame.

Runt Frame.

When set, this bit indicates that frame was prematurely terminated before the collision

window (64 bytes). Runt frames are passed on to the host only if the Pass Bad Frames bit (PASSBAD)

of the Host MAC Control Register (HMAC_CR) is set.

Multicast Frame.

When set, this bit indicates that the received frame has a Multicast address.

9:8

Reserved.

These bits are reserved. Reads 0.

Frame Too Long.

When set, this bit indicates that the frame length exceeds the maximum Ethernet

specification of 1518 bytes. This is only a frame too long indication and will not cause the frame recep-

tion to be truncated.

Collision Seen.

When set, this bit indicates that the frame has seen a collision after the collision win-

dow. This indicates that a late collision has occurred.

Frame Type.

When set, this bit indicates that the frame is an Ethernet-type frame (Length/Type field in

the frame is greater than 1500). When reset, it indicates the incoming frame was an 802.3 type frame.

This bit is not set for Runt frames less than 14 bytes.

Receive Watchdog time-out.

When set, this bit indicates that the incoming frame was greater than or

equal to 2048 bytes, therefore expiring the Receive Watchdog Timer. Frames greater than or equal to

2049 bytes are truncated to 2048 bytes and would most likely have a CRC error as a result.

MII Error.

When set, this bit indicates that a receive error was detected during frame reception.

Dribbling Bit.

When set, this bit indicates that the frame contained a non-integer multiple of 8 bits. This

error is reported only if the number of dribbling bits in the last byte is at least 3 in the 10 Mbps operating

mode. This bit will not be set when the collision seen bit[6] is set. If set and the CRC error bit is [1] reset,

then the packet is considered to be valid.

CRC Error.

When set, this bit indicates that a CRC error was detected. This bit is also set when the

RX_ER pin is asserted during the reception of a frame even though the CRC may be correct. This bit is

not valid if the received frame is a Runt frame, or a late collision was detected.

Reserved.

These bits are reserved. Reads 0

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