Atmel SpW-10X Control Logic And Operational Modes, Spacewire Link Control, Default operating mode

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

8. CONTROL LOGIC AND OPERATIONAL MODES

In this section the SpaceWire router control logic and operational modes are defined. The router control logic determines how the SpaceWire link ports operate, how received packets are routed to their destination and how the timeout mechanism detects packet blockages in the router.

8.1 SPACEWIRE LINK CONTROL

Each of the eight SpaceWire links has an associated SpaceWire control register. The register records status information from each link including link error information, link state and run status (see section 9.4.3).

The SpaceWire link control bits determine how the SpaceWire link operates. The link control bits are Auto-start (default), Link-Start, Link-Disable and Deactivate. The SpaceWire link data rate divider can also be set in the link control register.

The following paragraphs define each of the link control functions

8.1.1 Default operating mode

The default operating mode is Auto-Start. This is the mode setting for each link after power on or reset.

8.1.2 Auto-Start

In auto-start mode the SpaceWire port will remain inactive until a connection attempt is made by the SpaceWire device at the other end of the SpaceWire link. The port will then start-up and make the connection

The Auto-Start mode in conjunction with the automatic Link-Start and disable modes can help reduce power consumption by only activating SpaceWire links when packet data is transferred. See section 0.

8.1.3 Link-Start

The link-start control bit commands the SpaceWire port to try to make a connection with a SpaceWire device at the other end of the link. Assuming a SpaceWire device is connected to the other end of the link the SpaceWire port will move to state Run. Data transfer can take place when the link is started and the Link state is Run.

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