IP100A LF
Preliminary Data Sheet
55/97
March. 30, 2007
Copyright © 2004, IC Plus Corp.
IP100A LF-DS-R17
BIT
BIT NAME
R/W
BIT DESCRIPTION
11
Reserved
N/A
Reserved for future use.
15..12
Reserved
N/A
Reserved for future use.
11.4.10 MACCtrl0
Class............................. LAN I/O Registers, Control and Status
Base Address ............... IoBaseAddress register value
Address Offset .............. 0x50
Default .......................... 0x0000
Width ............................ 16 bits
BIT
BIT NAME
R/W
BIT DESCRIPTION
1..0
IFSSelect
R/W
Inter-Frame Spacing Select. IFSSelect indicates the minimum
number of bit times between the end of one Ethernet frame, and the
beginning of another when the IP100A LF is deferring after a
collision with the IP100A LF the last device to successfully acquire
the network (in half duplex mode). By selecting a large value for
IFSSelect, the IP100A LF will become less “aggressive” on the
network and may defer more often (preventing the IP100A LF from
“capturing” the network). The performance of the IP100A LF may
decrease as the IFSSelect value is increased from the standard
value.
BIT1
BIT0
INTER-FRAME SPACING IN BIT TIMES
0
0
96 (802.3 standard value, and default)
0
1
128
1
0
224
1
1
544
4..2
Reserved
N/A
Reserved for future use.
5
FullDuplexEnable
R/W
Full Duplex Enable. Setting FullDuplexEnable to a logic 1
configures the IP100A LF to function in a full duplex manner.
When operating in full duplex, the IP100A LF disables transmitter
deference to receive traffic, allowing simultaneous receive and
transmit traffic. Operation in full duplex has the side-effect of
disabling CarrierSenseErrors statistics collection, since full duplex
operation requires carrier sense to be masked to the transmitter.
TxReset and RxReset bits in AsicCtrl must be set for changes
ofFullDuplexEnable to take effect.
6
RcvLargeFrames
R/W
Receive Large Frames. RcvLargeFrames determines the frame size
at which the RxOversizedFrame bit of the RxFrameStatus field is set
for receive frames. When RcvLargeFrames is a logic 0, minimum
OversizedFrame size is 1514 bytes. When RcvLargeFrames is set,
minimum OversizedFrame size is 4491 bytes. (This value was the
maximum FDDI frame size of 4500 bytes, subtracting bytes for fields
that have no Ethernet equivalent.)
The frame size at which an OversizedFrame error will be flagged
includes the destination and source addresses, the type/length
field, and the FCS field.
7
Reserved
N/A
Reserved for future use.
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