Ref.:
UoD_SpW-10X_
UserManual
Issue:
3.4
SpW-10X
SpaceWire Router
User Manual
Date:
11
th
July 2008
Preliminary
144
WARNING
The deactivate mode (see also section 9.4.3) does not tri-state the LVDS outputs. The LVDS outputs
are cold-sparing and when disabled both outputs in an LVDS differential pair are pulled up to 3.3V and
have an impedance of the order of 1 kohm. Since they are differential outputs and are both are at the
same voltage no current will flow. If, however, external noise bias resistors are being used then a
small current (around 200 µA, 0.7 mW power) can flow. This is substantially less than the normal
operating current of LVDS outputs and hence saves power.
WARNING
In most onboard applications it is recommended to have Stat_mux_out(4) pulled low by default in
order to enable the watchdog timers on reset.
WARNING
When the watchdog timers are not enabled the SpaceWire and external ports can block indefinitely if,
for example, a source stops sending data in the middle of a packet. If watchdog timers are not enabled
then it must be possible for a network manager to detect blocking situations and to reset the router or
node creating the problem.
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.
WARNING
Blocking Allowed mode is not recommended and should be used with caution.
When Blocking Allowed mode is used (Watchdog timers disabled) then it is important that provision is
made for a network manager to detect blocking situations and to reset the nodes or routers causing
the problem.