Atmel SpaceWire Router SpW-10X User Manual

Ref.:   UoD_SpW-10X_ 

 

Issue:  3.4 

  

 

Date:  11

 

 

89

 

8.3.2.3  Arbitration of packets with different priority (1) 

In the Figure 8-8 arbitration of packets with different priority is illustrated. Only router ports 1-5 are 
shown for clarity.   

At stage one input ports 1 and 3 have packets with logical addresses 80 and 52 respectively, which 
are both to be routed to output port 5.  Logical address 80 is high priority and 52 low priority.  

At stage two the previous input port selected by output port 5 was input port 2 but since input port 1 
has a packet waiting with logical address 80 which is high priority, input port 1 will be selected first and 
the packet with logical address 80 transferred to output port 5.  

At stage three the high priority packet with logical address from input port 1 has been transferred and 
the remaining low priority packet from input port 3 is selected by the router to be transferred to output 
port 5. 

R1

2

5

1

3

52

4

80

R1

2

5

1

3

52

4

Two packets waiting to use port 5 

(Previous port which accessed port 5 = 2)

HIGH priority Packet from port 1 is selected

Packet at port number 3 waits

R1

2

5

1

3

4

Packet from port 3 is selected

R1

2

5

1

3

4

Packet from port 3 completes

1

2

3

4

Addresses
80 – HIGH Priority
52 – LOW Priority