ETHERNET CONTROLLER
CAM Control Register
S3C4510B
The three accept bits in the CAM control register are used to override CAM rejections. To place the MAC in
promiscuous mode, use CAM control register settings to accept packets with all three types of destination
addresses. The three types of destination address packets are as follows:
— Station packets, which has an even first byte. For example, 00-00-00-00-00-00.
— A multicast-group, which has an odd first byte, but which is not FF-FF-FF-FF-FF-FF. For example, 01-00-00-
00-00-00.
— A broadcast, defined as FF-FF-FF-FF-FF-FF.
When you enable CAM compare mode, the CAM memory reads the destination addresses to filter incoming
messages. (You will recall that the CAM memory consists of 6-byte entries.) An alternative way to place the MAC
in promiscuous mode is to set, in turn, to accept the them. To reject all packets, simply clear all of the bits in the
CAMCON register.
Table 7-20. CAMCON Register
Registers
CAMCON
Offset
R/W
Description
Reset Value
0XA004
R/W
CAM control
0x00000000
Table 7-21. CAM Control Register Description
Bit Name Description
Bit Number
[0]
Station accept (StationAcc)
Set this bit to accept any packet with a "unicast" station
address.
[1]
[2]
[3]
Group accept (GroupAcc)
Accept any packet with a multicast-group address.
Broadcast accept (BroadAcc) Accept any packet with a broadcast address.
Negative CAM (NegCAM)
When this bit is "0", packets the CAM recognizes are accepted
and others are rejected. When "1", packets the CAM
recognizes are rejected and others are accepted.
[4]
Compare enable (CompEn)
Reserved
Set this bit to enable compare mode.
Not applicable.
[31:5]
7-36
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