Table 3.18 filter i crc-16 bit definitions, Table 3.19 wakeup generation cases, Magic packet detection – SMSC LAN9420 User Manual

Page 59: Table 3.18, Datasheet

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Datasheet

SMSC LAN9420/LAN9420i

Revision 1.22 (09-25-08)

DATASHEET

Table 3.19

indicates the cases that produce a wake when the

Wakeup Frame Enable (WAKE_EN)

bit

of the

Wakeup Control and Status Register (WUCSR)

is set. All other cases do not generate a wake.

Note 3.2

As determined by bit 0 of Filter i Command.

Note 3.3

CRC matches Filter i CRC-16 field.

Note 3.4

As determined by bit 9 of WUCSR.

Note 3.5

As determined by bit 2 of Filter i Command.

Note: x indicates “don’t care”.

3.5.4.1

Magic Packet Detection

Setting the Magic Packet Enable bit (MPEN) in the

Section 4.4.12, "Wakeup Control and Status

, places the MAC in the “Magic Packet” detection mode. In this mode,

normal data reception is disabled, and detection logic within the MAC examines receive data for a
Magic Packet. The MAC can be programmed to assert the wake event interrupt to the Interrupt
Controller on detection. Upon detection, the Magic Packet Received bit (MPR) in the WUCSR is set.
When the Host clears the MPEN bit, normal receive operation will resume. Please refer to

Section

4.4.12, "Wakeup Control and Status Register (WUCSR)," on page 133

for additional information on this

In Magic Packet mode, logic within the MAC constantly monitors each frame addressed to the node
for a specific Magic Packet pattern. It checks only packets with the MAC’s address or a broadcast
address to meet the Magic Packet requirement. The MAC checks each received frame for the pattern
48’hFF_FF_FF_FF_FF_FF after the destination and source address field.

Table 3.18 Filter i CRC-16 Bit Definitions

FILTER i CRC-16 DESCRIPTION

BITS

DESCRIPTION

15:0

Pattern CRC-16: This field contains the 16-bit CRC value from the pattern and the byte mask
programmed to the wakeup filter register function. This value is compared against the CRC
calculated on the incoming frame, and a match indicates the reception of a wakeup frame.

Table 3.19 Wakeup Generation Cases

FILTER

ENABLED

(

Note 3.2

)

CRC

MATCH

(

Note 3.3

)

GLOBAL