LAN9117 Datasheet, PDF (21/114 Pages) SMSC Corporation – HIGH PERFORMANCE SINGLE-CHIP 10/100 NON-PCI ETHERNET CONTROLLER

LAN9117
3.4.2.2 Inverse Filtering
In inverse filtering, the LAN9117 Packet Filter Block accepts incoming frames with a destination address not matching
the perfect address (i.e., the value programmed into the MAC Address High register and the MAC Address Low register
in the CRC block and rejects frames with destination addresses matching the perfect address.
For all filtering modes, when MCPAS is set, all multicast frames are accepted. When the PRMS bit is set, all frames are
accepted regardless of their destination address. This includes all broadcast frames as well.
3.5 Wake-up Frame Detection
Setting the Wake-Up Frame Enable bit (WUEN) in the “WUCSR—Wake-up Control and Status Register”, places the
LAN9117 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 LAN9117 can be pro-
grammed 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 LAN9117 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, "WUFF—Wake-up Frame Filter," on page 87 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 reg-
ister’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 Table 3-2, "Wake-Up Frame Filter Register Structure"
below, shows the wake-up frame filter register’s structure.
Note 3-1
Wake-up frame detection can be performed when LAN9117 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 WUCSR—Wake-up Control and
Status Register, a broadcast wake-up frame will wake-up the device despite the state of the Disable
Broadcast Frames (BCAST) bit in the MAC_CR—MAC Control Register.
TABLE 3-2: WAKE-UP FRAME FILTER REGISTER STRUCTURE
Filter 0 Byte Mask
Filter 1 Byte Mask
Filter 2 Byte Mask
Filter 3 Byte Mask
Reserved
Filter 3
Command
Reserved
Filter 2
Command
Reserved
Filter 1
Command
Reserved
Filter 0
Command
Filter 3 Offset
Filter 2 Offset
Filter 1Offset
Filter 0 Offset
Filter 1 CRC-16
Filter 0 CRC-16
Filter 3 CRC-16
Filter 2 CRC-16
The Filter i Byte Mask defines which incoming frame bytes Filter i will examine to determine whether or not this is a
wake-up frame. Table 3-3, describes the byte mask’s bit fields.
 2005-2016 Microchip Technology Inc.
DS00002267A-page 21