LAN89218 datasheet(109/148 Pages) MICROCHIP

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DS60001255B-page 109

LAN89218

5.4.11

WUFF—WAKEUP FRAME FILTER

This register is used to configure the wake up frame filter.

Offset:

Attribute:

R/W

Default Value:

00000000h

Size:

32 bits

Bits

Description

31:0

Wakeup Frame Filter (WFF). The Wakeup Frame Filter is configured through this register using an

indexing mechanism. Following a reset, the MAC loads the first value written to this location to the first

DWORD in the Wakeup Frame Filter (filter 0 byte mask). The second value written to this location is

loaded to the second DWORD in the Wakeup Frame Filter (filter 1 byte mask) and so on. Once all eight

DWORDs have been written, the internal pointer will once again point to the first entry and the filter

entries can be modified in the same manner. Similarly, eight DWORDs can be read sequentially to

obtain the values stored in the WFF.

Note:

This register should be read and written using eight consecutive DWORD operations. Failure

to read or write the entire contents of the WFF may cause the internal read/write pointers to

be left in a position other than pointing to the first entry. A mechanism for resetting the inter-

nal pointers to the beginning of the WFF is available via the WFF Pointer Reset

(WFF_PTR_RST) bit of the WUCSR—Wake-up Control and Status Register. This mecha-

nism enables the application program to re-synchronize with the internal WFF pointers if it

has not previously read/written the complete contents of the WFF.

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