Atmel SpaceWire Router SpW-10X Manual Do Utilizador

Ref.:   UoD_SpW-10X_ 

 

Issue:  3.4 

  

 

Date:  11

 

 

144

 

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.  

 

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. 

 

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. 

 

 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. 

 

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.