R

Chapter 9: Configuration and Status

These signals may be changed by the user application at any time. The Clock Domain heading denotes the clock domain the configuration signal is registered in before use by the core. It is not necessary to drive the signal from this clock domain.

Table 9-36:Optional Configuration and Status Vectors

Signal

Direction

Clock

Description

Domain

 

 

 

 

configuration_vector

Input

See

Bit[0]: Reserved (currently unused)

[3:0]

 

note 1

Bit[1]: Loopback Control

 

 

 

 

 

 

• When used with a RocketIO transceiver, the

 

 

 

core is placed in internal loopback mode.

 

 

 

• With the TBI version, Bit 1 is connected to

 

 

 

ewrap. When set to ‘1,’ this indicates to the

 

 

 

external PMA module to enter loopback mode.

 

 

 

See “Loopback,” page 197.

 

 

 

Bit[2]: Power Down

 

 

 

• When a RocketIO transceiver is used, a

 

 

 

setting of ‘1’ places the RocketIO in a low-

 

 

 

power state. A reset must be applied to clear.

 

 

 

• With the TBI version, this bit is unused.

 

 

 

Bit[3]: Isolate

 

 

 

• When set to ‘1,’ the GMII should be

 

 

 

electrically isolated.

 

 

 

• When set to ‘0,’ normal operation is enabled.

 

 

 

 

1.Signals are synchronous to the core’s internal 125 MHz reference clock; this is userclk2 when used with a RocketIO transceiver; gtx_clk when used with TBI.

152

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Ethernet 1000BASE-X PCS/PMA or SGMII v9.1

 

 

UG155 March 24, 2008

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Xilinx 1000BASE-X manual 36Optional Configuration and Status Vectors, Signal Direction Clock Description Domain