LAN9221 Datasheet, PDF(27/151 Page) SMSC Corporation – High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O

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LAN9221 Datasheet, PDF (27/151 Pages) SMSC Corporation – High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O

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High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O

Datasheet

3.5

Wake-up Frame Detection

Setting the Wake-Up Frame Enable bit (WUEN) in the âWUCSRâWake-up Control and Status

Registerâ, places the LAN9221/LAN9221i MAC in the wake-up frame detection mode. In this mode,

normal data reception is disabled, and detection logic within the MAC examines receive data for the

pre-programmed wake-up frame patterns. The LAN9221/LAN9221i can be programmed to notify the

host of the wake-up frame detection with the assertion of the host interrupt (IRQ) or assertion of the

power management event signal (PME). Upon detection, the Wake-Up Frame Received bit (WUFR) in

the WUCSR is set. When the host clears the WUEN bit the LAN9221/LAN9221i will resume normal

receive operation.

Before putting the MAC into the wake-up frame detection state, the host must provide the detection

logic with a list of sample frames and their corresponding byte masks. This information is written into

the Wake-up Frame Filter register (WUFF). Please refer to Section 5.4.11, "WUFFâWake-up Frame

Filter," on page 116 for additional information on this register.

The MAC supports four programmable filters that support many different receive packet patterns. If

remote wake-up mode is enabled, the remote wake-up function receives all frames addressed to the

MAC. It then checks each frame against the enabled filter and recognizes the frame as a remote wake-

up frame if it passes the wakeup frame filter registerâs address filtering and CRC value match.

In order to determine which bytes of the frames should be checked by the CRC module, the MAC uses

a programmable byte mask and a programmable pattern offset for each of the four supported filters.

The patternâs offset defines the location of the first byte that should be checked in the frame. Since

the destination address is checked by the address filtering Function, the pattern offset is always greater

than 12.

The byte mask is a 31-bit field that specifies whether or not each of the 31 contiguous bytes within

the frame, beginning in the pattern offset, should be checked. If bit j in the byte mask is set, the

detection logic checks byte offset +j in the frame. In order to load the Wake-up Frame Filter register,

the host LAN driver software must perform eight writes to the Wake-up Frame Filter register (WUFF).

The Diagram shown in Table 3.2, "Wake-Up Frame Filter Register Structure" below, shows the wake-

up frame filter registerâs structure.

Note 3.1

Wake-up frame detection can be performed when the LAN9221/LAN9221i is in the D0 or

D1 power states. In the D0 state, wake-up frame detection is enabled when the WUEN bit

is set.

Note 3.2 Wake-up frame detection, as well as Magic Packet detection, is always enabled and

cannot be disabled when the device enters the D1 state.

Note 3.3

When wake-up frame detection is enabled via the WUEN bit of the WUCSRâWake-up

Control and Status Register, a broadcast wake-up frame will wake-up the device despite

the state of the Disable Broadcast Frame (BCAST) bit in the MAC_CRâMAC Control

SMSC LAN9221/LAN9221i

DATASHEET

Revision 2.6 (12-04-08)

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