DocID018909 Rev 11
RM0090
Ethernet (ETH): media access control (MAC) with DMA controller
1232
Ethernet MAC hash table high register (ETH_MACHTHR)
Address offset: 0x0008
Reset value: 0x0000 0000
The 64-bit Hash table is used for group address filtering. For hash filtering, the contents of
the destination address in the incoming frame are passed through the CRC logic, and the
upper 6 bits in the CRC register are used to index the contents of the Hash table. This CRC
is a 32-bit value coded by the following polynomial (for more details refer to
Bits 7:6
PCF:
Pass control frames
These bits control the forwarding of all control frames (including unicast and multicast
PAUSE frames). Note that the processing of PAUSE control frames depends only on RFCE
in Flow Control Register[2].
00: MAC prevents all control frames from reaching the application
01: MAC forwards all control frames to application except Pause control frames
10: MAC forwards all control frames to application even if they fail the address filter
11: MAC forwards control frames that pass the address filter.
These bits control the forwarding of all control frames (including unicast and multicast
PAUSE frames). Note that the processing of PAUSE control frames depends only on RFCE
in Flow Control Register[2].
00 or 01: MAC prevents all control frames from reaching the application
10: MAC forwards all control frames to application even if they fail the address filter
11: MAC forwards control frames that pass the address filter.
Bit 5
BFD:
Broadcast frames disable
When this bit is set, the address filters filter all incoming broadcast frames.
When this bit is reset, the address filters pass all received broadcast frames.
Bit 4
PAM:
Pass all multicast
When set, this bit indicates that all received frames with a multicast destination address (first
bit in the destination address field is '1') are passed.
When reset, filtering of multicast frame depends on the HM bit.
Bit 3
DAIF:
Destination address inverse filtering
When this bit is set, the address check block operates in inverse filtering mode for the DA
address comparison for both unicast and multicast frames.
When reset, normal filtering of frames is performed.
Bit 2
HM:
Hash multicast
When set, MAC performs destination address filtering of received multicast frames
according to the hash table.
When reset, the MAC performs a perfect destination address filtering for multicast frames,
that is, it compares the DA field with the values programmed in DA registers.
Bit 1
HU:
Hash unicast
When set, MAC performs destination address filtering of unicast frames according to the
hash table.
When reset, the MAC performs a perfect destination address filtering for unicast frames, that
is, it compares the DA field with the values programmed in DA registers.
Bit 0
PM:
Promiscuous mode
When this bit is set, the address filters pass all incoming frames regardless of their
destination or source address. The SA/DA filter fails status bits in the receive status word
are always cleared when PM is set.
