LAN9221i SMSC [SMSC Corporation], LAN9221i Datasheet - Page 27

• Manufacturer Part Number: LAN9221i
• Description: High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O
• Manufacturer: SMSC [SMSC Corporation]

High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O
Datasheet
SMSC LAN9221/LAN9221i
3.5
Setting the Wake-Up Frame Enable bit (WUEN) in the “WUCSR—Wake-up Control and Status
Register”, 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
Filter," on page 116
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 register’s 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 pattern’s 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
up frame filter register’s structure.
Note 3.1
Note 3.2
Note 3.3
Wake-up Frame Detection
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.
Wake-up frame detection, as well as Magic Packet detection, is always enabled and
cannot be disabled when the device enters the D1 state.
When wake-up frame detection is enabled via the WUEN bit of the
Control and Status
the state of the Disable Broadcast Frame (BCAST) bit in the
Register.
for additional information on this register.
Table 3.2, "Wake-Up Frame Filter Register Structure"
Register, a broadcast wake-up frame will wake-up the device despite
DATASHEET
27
Section 5.4.11, "WUFF—Wake-up Frame
MAC_CR—MAC Control
below, shows the wake-
WUCSR—Wake-up
Revision 2.6 (12-04-08)