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IXF1104 4-Port Gigabit Ethernet Media Access Controller
Datasheet 167
Document Number: 278757
Revision Number: 007
Revision Date: March 25, 2004
Table 84. FC Enable ($ Port_Index + 0x12)
Bit Name Description Type
1
Default
Register Description:
Indicates which flow control mode is used for the RX and TX MAC. 0x00000007
31:3 Reserved Reserved R 0x00000000
2TX HDFC
When TX HDFC is enabled (half-duplex mode
only), the MAC generates deliberate collisions on
incoming packets when the RX FIFO occupancy
crosses the High Watermark (flow control).
0 = Disable TX half-duplex flow control
1 = Enable TX half-duplex flow control
R/W 1
1TX FDFC
0 = Disable TX full-duplex flow control [the MAC
will not generate internally any flow control
frames based on the RX FIFO watermarks or
the Transmit Pause Control interface
1 = Enable TX full-duplex flow control [enables
the MAC to send flow control frames to the
link partner based on the RX FIFO
programmable watermarks or the Transmit
Pause Control interface]
R/W 1
0RX FDFC
0 = Disable RX full-duplex flow control [the MAC
will not respond to flow control frames sent to
it by the link partner]
1 = Enable RX full-duplex flow control [MAC will
respond to flow control frames sent by the link
partner and will stop packet transmission for
the time specified in the flow control frame]
R/W 1
1. RO = Read Only, No clear on Read; R = Read, Clear on Read; W = Write only; R/W = Read/Write, No
clear; R/W/C = Read/Write, Clear on Write
Table 85. FC Back Pressure Length ($ Port_Index + 0x13)
Name Description Address Type
1
Default
FC Back Pressure
Length
This register sets number the byte cycles
for which the collision has to be applied.
The 6-bit configuration holds the value in
bytes, which applies to the minimum
length/duration of back pressure in half-
duplex mode. Flow control in the receive
path is executed by deliberately colliding
the incoming packets in half-duplex mode.
Register bits 5:0 are used alone.
Port Add +
0x13
R/W 0x0000000C
1. RO = Read Only, No clear on Read; R = Read, Clear on Read; W = Write only; R/W = Read/Write, No
clear; R/W/C = Read/Write, Clear on Write