Atmel SpW-10X Control Logic And Routing, Packet address error, Arbitration, SpaceWire Router

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

1

2

3

4

Packet with address 2

			Auto-Start default mode
			and Start on Request enabled
			and Disable on Silence
			enable in both routers
1	R1	2		1	R2	2

1	R1	2		1	R2	2
			Connection Attempt

1 R1 2 1 R2 2

Link Started and Data transfer

1 R1 2 1 R2 2

Data transfer completed

Link Disabled after timeout period

Figure 8-5 Disable on Silence mode

The SpaceWire router Disable on Silence mode is used to disable a SpaceWire link when it no longer has any data to transfer. The Disable on Silence mode is enabled only when the router timeouts are enabled. The SpaceWire port is disabled if no data or end of packet character has been transmitted for the timeout period set in the router control register.

The SpaceWire router will only disable a SpaceWire port when the SpaceWire router is the source of the data transfer. If an external device starts the SpaceWire link or sends packet data to the router through the link then the link will not be disabled.

8.3 CONTROL LOGIC AND ROUTING

This section describes the operation of the SpaceWire routing logic and how packets are handled for different modes of operation of the router. The following control bits in the router control register affect the router operating mode: Timeout Enable, Enable Disable on Silence, Enable Start on Request and Enable self-addressing.

8.3.1 Packet address error

When a packet with an invalid address, see section 7.4, is received the packet is discarded by the router. The router is ready to receive the next packet as soon as the invalid address packet has been spilt.

8.3.2 Arbitration

Arbitration is performed by the SpaceWire router when two or more packets are to be routed through the same destination port. The router chooses the next packet to be routed to a particular output port

Preliminary 86