LAN9353 Datasheet, PDF (111/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
Register B (PHY_WUF_CFGB_x), and PHY x Wakeup Filter Byte Mask Registers (PHY_WUF_MASK_x). The starting
offset within the frame and the expected CRC-16 for the filter is determined by the Filter Pattern Offset and Filter CRC-
16 fields, respectively.
If remote wakeup mode is enabled, the remote wakeup function checks each frame against the filter and recognizes the
frame as a remote wakeup frame if it passes the filter’s address filtering and CRC value match.
The pattern 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 with the pattern offset,
should be checked. If bit j in the byte mask is set, the detection logic checks the byte (pattern offset + j) in the frame,
otherwise byte (pattern offset + j) is ignored.
At the completion of the CRC-16 checking process, the CRC-16 calculated using the pattern offset and byte mask is
compared to the expected CRC-16 value associated with the filter. If a match occurs, a remote wake-up event is sig-
naled. The frame must also pass the FCS check and packet length checking.
Table 9-5 indicates the cases that produce a wake-up event. All other cases do not generate a wake-up event.
TABLE 9-5: WAKEUP GENERATION CASES
Filter
Enabled
Yes
Yes
Yes
Yes
Yes
Frame
Type
Unicast
Unicast
Multicast
Multicast
Broadcast
CRC
Matches
Yes
Yes
Yes
Yes
Yes
Address
Match
Enabled
No
Yes
X
Yes
X
Any
Mcast
Enabled
X
X
Yes
No
X
Bcast
Enabled
X
X
X
X
Yes
Frame
Address
Matches
X
Yes
X
Yes
X
As an example, the Host system must perform the following steps to enable the device to detect a Wakeup Frame WoL
event:
Declare Pattern:
1. Update the PHY x Wakeup Filter Byte Mask Registers (PHY_WUF_MASK_x) to indicate the valid bytes to match.
2. Calculate the CRC-16 value of valid bytes offline and update the PHY x Wakeup Filter Configuration Register B
(PHY_WUF_CFGB_x). CRC-16 is calculated as follows:
At the start of a frame, CRC-16 is initialized with the value FFFFh. CRC-16 is updated when the pattern offset
and mask indicate the received byte is part of the checksum calculation. The following algorithm is used to update
the CRC-16 at that time:
Let:
^ denote the exclusive or operator.
Data [7:0] be the received data byte to be included in the checksum.
CRC[15:0] contain the calculated CRC-16 checksum.
F0 … F7 be intermediate results, calculated when a data byte is determined to be part of the CRC-16.
Calculate:
F0 = CRC[15] ^ Data[0]
F1 = CRC[14] ^ F0 ^ Data[1]
F2 = CRC[13] ^ F1 ^ Data[2]
F3 = CRC[12] ^ F2 ^ Data[3]
F4 = CRC[11] ^ F3 ^ Data[4]
F5 = CRC[10] ^ F4 ^ Data[5]
 2015 Microchip Technology Inc.
DS00001925A-page 111