Atmel SpaceWire Router SpW-10X - Manual (Page 79)

Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual Date: 11 th
July 2008
Preliminary
79
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.