Atmel SpW-10X user manual Link-Disable, Automatic deactivate driver mode

SpW-10X	Ref.:	UoD_SpW-10X_
SpaceWire Router		UserManual
	Issue:	3.4
User Manual
	Date:	11th July 2008

8.1.4 Link-Disable

The SpaceWire port can be disabled therefore rendering the link unusable. When a SpaceWire link which is running is disabled it will disconnect from the far end and refuse connection attempts by the far end of the link. Caution should be used when using this command for a stand alone router as disabling all the links will leave the router unusable, except through a reset operation.

WARNING

If the link that is being used to configure the router is disabled then it will not be possible to configure the router, unless there is another not disabled connection that can be used.

8.1.5 Automatic deactivate driver mode

The SpaceWire port deactivate bit can be set to cause the data and strobe outputs for the link to be deactivated when the port is inactive. The deactivate mode takes effect dependent on the state of the Auto-start and the Link-Disabled control bits in the SpaceWire port control register (see section 9.4.3) and on the Enable Start on Request bit in the router control register (see section 9.5.3).

When Auto-start is enabled and the deactivate bit is set then the data and strobe LVDS drivers are deactivated until the interface receives a connection attempt by an external SpaceWire device. The drivers are then enabled until the external device disconnects the link or the SpaceWire link control bit setup is changed.

When Start on Request is enabled and the deactivate bit is set the LVDS drivers are deactivated until a request is made from within the router to send data out of the SpaceWire port with deactivated output drivers i.e. a packet arriving at another port is addressed to be routed out of the SpaceWire port with deactivated outputs. The drivers are enabled and the SpaceWire port will attempt to make a connection with the other end of the SpaceWire link.

When Link-disable is asserted and the deactivate bit is set then the data and strobe LVDS drivers are always deactivated as the link is not in use.

The figure below shows the effect of the deactivate bit when the link setting is Auto-start only.

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