LAN9730 Datasheet, PDF (65/222 Pages) SMSC Corporation – High-Speed Inter-Chip (HSIC) USB 2.0

LAN9730/LAN9730i
4.5.4.3 Hash Perfect Filtering
In hash Perfect Filtering, if the received frame is a physical address, the device’s Packet Filter Block perfect filters the
incoming frame’s destination field with the value programmed into the MAC Address High register and the MAC Address
Low register. If the incoming frame is a multicast frame, however, the device’s packet filter function performs an imper-
fect address filtering against the hash table.
The imperfect filtering against the hash table is the same imperfect filtering process described in Section 4.5.4.2, "Hash
Only Filtering Mode".
4.5.4.4 Inverse Filtering
In Inverse Filtering, the 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.
4.5.5 WAKEUP FRAME DETECTION
Setting the Wakeup Frame Enable (WUEN) bit in the Wakeup Control and Status Register (WUCSR), places the MAC
in the Wakeup Frame Detection mode. In this mode, normal data reception is disabled, and detection logic within the
MAC examines receive data for the pre-programmed Wakeup Frame patterns. When a wakeup pattern is received, the
Remote Wakeup Frame Received (WUFR) bit in the WUCSR is set, the device places itself in a fully operational state,
and remote wakeup is issued. The host will then resume the device and read the WUSCR register to determine the
condition that caused the remote wakeup. Upon determining that the WUFR bit is set, the host will know a Wakeup
Frame detection event was the cause. The host will then clear the WUFR bit, and clear the WUEN bit to resume normal
receive operation. Refer to Section 6.4.12, "Wakeup Control and Status Register (WUCSR)" for additional information
on this register.
Before putting the MAC into the Wakeup 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 Wakeup Frame Filter register
(WUFF). Refer to Section 6.4.11, "Wakeup Frame Filter (WUFF)" for additional information on this register.
Table 4-46 indicates the number of Wakeup Frame Filters contained in the WUFF.The number of writes/reads required
to program the WUFF or read its contents, respectively, is also indicated.
TABLE 4-46: WAKEUP FRAME FILTER CAPACITY
Number of Filters
8
Number of Writes/Reads
40
The programmable filters support many different receive packet patterns. If remote wakeup mode is enabled, the remote
wakeup function receives all frames addressed to the MAC. It then checks each frame against the enabled filter and
recognizes the frame as a remote Wakeup Frame if it passes the WUFF’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 supported filters.
The pattern’s offset defines the location of the first byte that should be checked in the frame. The byte mask is a 128-
bit field that specifies whether or not each of the 128 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 Wakeup Frame Filter register, the host LAN driver software must perform the number of writes indi-
cated in Table 4-46 to the device’s Wakeup Frame Filter register (WUFF). The contents of the Wakeup Frame Filter reg-
ister may be obtained by reading it. The number of reads required to extract the entire contents of the device’s WUFF
is also indicated in Table 4-46.
Table 4-47 shows the Wakeup Frame Filter register’s structure.
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DS00001946A-page 65