Atmel SpaceWire Router SpW-10X User Manual

Ref.:   UoD_SpW-10X_ 

 

Issue:  3.4 

  

 

Date:  11

 

 

97

 

R1

1

2

3

4

5

6

(c)

R2

1

4

2

3

5

6

4

4

 

What happens when the routers are in Watchdog Timer mode and a destination becomes blocked is 
illustrated in Figure 8-17to Figure 8-20. Only SpaceWire ports 1 to 6 are shown for clarity.  

a)  A packet arrives at port 3 of routing switch R1 destined for port 4 and then port 5 of R2 

R1

1

2

3

4

5

6

(a)

4

5

R2

1

4

2

3

5

6

4

4

 

b)  The packet is routed towards its destination but during packet transfer the destination stalls 

and does not accept further data. The network path is blocked and the packet waiting at R1 
port 2 is also blocked 

R1

1

2

3

4

5

6

(b)

R2

1

4

2

3

5

6

4

4

 

c)  At routing switches R1 and R2 the watchdog timers detect the packet has blocked for the 

specified timeout period. The packet is then discarded by the routers by spilling the data at the 
input port and appending an EEP to the data at the output ports. Once the packet has been 
removed from the network an EEP is ready to be appended to routing switch R2 port 5 when 
buffer space is available and the network path between routing switch R1 port 4 and routing 
switch R2 port 1 is available.