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GD32F10x User Manual
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but the result will not affect whether current frame passes the filter or not.
Unicast frame destination address filter
For a unicast frame, application has two modes for filtering: the one is using static physical
address (by setting HUF bit to ‘0’), the other is using hash list (by setting HUF bit to ‘1’).
Static physical address (SPA) filtering
In the filter mode, MAC supports using four MAC addresses for unicast frame filtering. In this
way, the MAC compares all 6 bytes of the received unicast address to the programmed MAC
address. MAC address 0 is always used and MAC address 1 to address 3 can be configured
to use or not. Each byte of MAC address 1 to MAC address 3 register can be masked for
comparison with the corresponding destination address byte of received frame by setting the
corresponding mask byte bits (MB) in the corresponding register.
Hash list filtering
In this filter mode, MAC uses a HASH mechanism. MAC uses a 64-bit hash list to filter the
received unicast frame. This filter mode obeys the followings two filtering steps:
1)
The MAC calculates the CRC value of the received frame’s destination address.
2) Using the high 6 bits of the calculated CRC value as the index to retrieve the hash list. If
the corresponding value of hash list is 1, the received frame passes through the filter,
conversely, fail the filter.
The advantage of this type of filter is that it can cover any possible address just using a small
table. But the disadvantage is that the filter is imperfect and sometimes the frames should be
dropped are also be received by mistake.
Multicast frame destination address filter
Application can enable the multicast frame MAC address filtering by cleaning the MFD bit in
register ENET_MAC_FRMF. By configuring the value of HMF bit in ENET_MAC_FRMF
register application can choose two ways just like unicast destination address filtering for
address filtering.
Hash or perfect address filter
The destination address (DA) filter can be configured to pass a frame when its DA matches
either the hash list filter or the static physical address filter by setting the HPFLT bit in the
ENET_MAC_FRMF register and setting the corresponding HUF or HMF bit in the
ENET_MAC_FRMF register.
Broadcast frame destination address filter
At default, the MAC unconditionally receives the broadcast frames. But when setting BFRMD
bit in register ENET_MAC_FRMF, MAC discards all received broadcast frames.
Summary of Contents for GD32F10 Series
Page 63: ...GD32F10x User Manual 63 programmed during the chip production ...
Page 117: ...GD32F10x User Manual 117 010 1 0 011 0 9 ...
Page 416: ...GD32F10x User Manual 416 shadow register updates every update event ...
Page 427: ...GD32F10x User Manual 427 value ...
Page 518: ...GD32F10x User Manual 518 These bits are not used in SPI mode ...