DP83936AVF NSC [National Semiconductor], DP83936AVF Datasheet - Page 52

• Manufacturer Part Number: DP83936AVF
• Description: Full Duplex SONICTM-T Systems-Oriented Network Interface Controller with Twisted Pair Interface
• Manufacturer: NSC [National Semiconductor]

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6 0 SONIC-T Registers
6 4 7 Data Configuration Register 2 (Continued)
Bit
5
4
3
2
1
0
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FD FULL DUPLEX
This bit programs the SONIC-T to transmit and receive simultaneously (Full Duplex) This bit should only be set when
used in conjunction with a port that supports and is configured for Full Duplex Ethernet
0 Disable full duplex mode
1 Enable full duplex mode
PH PROGRAM HOLD
When this bit is set to ‘‘0’’ the HOLD request output is asserted deasserted from the falling edge of bus clock If this
bit is set to ‘‘1’’ HOLD will be asserted deasserted
Must be zero
PCM PACKET COMPRESS WHEN MATCHED
When this bit is set to a ‘‘1’’ (and the PCNM bit is reset to a ‘‘0’’) the PCOMP output will be asserted if the
destination address of the packet being received matches one of the entries in the CAM (Content Addressable
Memory) This bit along with PCNM is used with the Management Bus of the DP83950 Repeater Interface
Controller (RIC) See the DP83950 datasheet for more details on the RIC Management Bus This mode is also called
the Managed Bridge Mode
Note 1 Setting PCNM and PCM to ‘‘1’’ at the same time is not allowed
Note 2 If PCNM and PCM are both ‘‘0’’ the PCOMP output will remain TRI-STATE until PCNM or PCM are changed
PCNM COMPRESS WHEN NOT MATCHED
When this bit is set to a ‘‘1’’ (and the PCM bit is set to ‘‘0’’) the PCOMP output will be asserted if the destination
address of the packet does not match one of the entries in the CAM See the PCM bit above This mode is also
called the Managed Hub Mode
Note PCOMP will not be asserted if the destination address is a broadcast address This is true regardless of the state of the BRD bit in the
RJCM REJECT ON CAM MATCH
When this bit is set to ‘‘1’’ the SONIC-T will reject a packet on a CAM match Setting RJCM to ‘‘0’’ causes the
SONIC-T to operate normally by accepting packets on a CAM match Setting this mode is useful for a small bridge
with a limited number of nodes attached to it RJCM only affects the CAM though Setting RJCM will not invert the
function of the BRD PRO or AMC bits (to accept broadcast all physical or multicast packets respectively) in the
Receive Control Register (see Section 6 4 3) This means for example that it is not possible to set RJCM and BRD
to reject all broadcast packets If RJCM and BRD are set at the same time however all broadcast packets will be
accepted but any packets that have a destination address that matches an address in the CAM will be rejected
Receive Control Register
(Continued)
52
Description
clock later on the rising edge of bus clock