Atmel SpaceWire Router SpW-10X - Manual (Page 85)

Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual Date: 11 th
July 2008
Preliminary
85
8.2.1 Start on request mode
The Start on Request mode is enabled by setting the CFG_START_ON_REQ bit in the router control
register. The input signal POR_START_ON_REQ_N determines the power on or reset state of the
CFG_START_ON_REQ bit.
When a SpaceWire packet is received which is to be routed out of a SpaceWire port that is not
running it would normally be discarded. If the Start on Request mode is enabled instead of discarding
the packet the SpaceWire port will attempt to make a connection with the other end of the link. If a
connection can be made then the packet is forwarded on towards its destination. This is illustrated in
Figure 8-4. This mode allows the SpaceWire ports to be started automatically when there is data to
send. This can be used together with output deactivate to save power.
R1 R2 1 2 1 2
Auto-Start default mode
and Start on Request
enabled in both routers
R1 R2 1 2 1 2 2
Packet with
address 2
R1 R2 1 2 1 2
Connection Attempt
2
Link Started and
Data Transfer
1
2
3
2
Figure 8-4 Start on Request mode
8.2.2 Disable on Silence mode
The Disable on Silence mode is enabled by setting the CFG_DISABLE_ON_SILENCE bit in the router
control register. The input signal POR_DISABLE_ON_SILENCE_N determines the power on or reset
state of the CFG_DISABLE_ON_SILENCE bit.
Figure 8-5 illustrates operation in the Disable on Silence mode.