Xilinx 1000BASE-X manual Configuration and Status 15Status Register Register

R

Chapter 9: Configuration and Status

Table 9-15:Status Register (Register 1) (Continued)

Bit(s)	Name	Description	Attributes	Default
				Value
1.10	100BASE-T2 Full	Always returns a ‘0’ for this bit since	returns 0	0
	Duplex	100BASE-T2 Full Duplex is not supported
1.9	100BASE-T2 Half	Always returns a ‘0’ for this bit since	returns 0	0
	Duplex	100BASE-T2 Half Duplex is not supported
1.8	Extended Status	Always returns a ‘1’ for this bit to indicate	returns 1	1
		the presence of the Extended Register
		(Register 15)
1.7	Unidirectional Ability	Always returns 1, writes ignored	returns 1	1
1.6	MF Preamble	Always returns a ‘1’ for this bit to indicate	returns 1	1
	Suppression	that Management Frame Preamble
		Suppression is supported
1.5	Auto- Negotiation	Ignore this bit because Auto-Negotiation	returns 1	1
	Complete	is not included.
1.4	Remote Fault	Always returns a ‘0’ for this bit because	returns 0	0
		Auto-Negotiation is not included.
1.3	Auto- Negotiation	Ignore this bit because Auto-Negotiation	returns 0	0
	Ability	is not included.
1.2	Link Status1	1 = Link is up	read only	0
		0 = Link is down	self
		Latches '0' if Link Status goes down.	clearing
			on read
		Clears to current Link Status on read.
		See table note for Link Status behavior.
1.1	Jabber Detect	Always returns a ‘0’ for this bit since	returns 0	0
		Jabber Detect is not supported
1.0	Extended Capability	Always returns a ‘0’ for this bit since no	returns 0	0
		extended register set is supported

1.When high, the link is valid: synchronization of the link has been obtained and Auto-Negotiation (if present and enabled) has completed.

When low, a valid link has not been established. Either link synchronization has failed or Auto-Negotiation (if present and enabled) has failed to complete.

Regardless of whether Auto-Negotiation is enabled or disabled, there can be some delay to the deassertion of this signal following the loss of synchronization of a previously successful link. This is due to the Auto-Negotiation state machine which requires that synchronization is lost for an entire link timer duration before changing state. For more information, see the 802.3 specification.

132	www.xilinx.com	Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
		UG155 March 24, 2008