Atmel SpaceWire Router SpW-10X User Manual

Page of 155
Ref.:   UoD_SpW-10X_ 
UserManual
 
Issue:  3.4 
  
 
 
SpW-10X 
SpaceWire Router 
User Manual 
Date:  11
th
 July 2008 
 
 
Preliminary 
73
 
In Figure 7-11 the format of the reply to a write command is illustrated. The first byte sent by the 
SpaceWire router configuration logic is the port address followed by the destination logical address. 
Fields which are depicted in bold text are expected values. Fields which are shaded are optional. Note 
that the reply is always sent out of the same port as the command was received on. The Source Path 
Address should not include the output port of the router being commanded as the reply will be 
automatically sent out of the same port that the command arrived on. See section 7.6.8. 
Source Path Address
Source Logical Address
Protocol Identifier
01h
Packet Type, Command,
Source Path Addr Len
Status
Destination Logical Address
FEh
Transaction Identifier (MS)
Transaction Identifier (LS)
Reply CRC
Source Path Address
Source Path Address
EOP
First byte transmitted
Last byte transmitted
1
1
0
0
1
0
Bits in Packet Type / Command / Source Path Address Length Byte
MSB
Packet Type
Command
Source Path
Address Length
Source Path
Address Length
LSB
Source Path Address Length
 
Figure 7-11 Write Single Address Reply Packet 
 
Table 7-16 Write Single Address Reply Packet Fields 
Field Description 
Bytes
Source 
Path 
Address  
Optional source path addresses specified in the command packet. If no source 
path addresses are specified then the first byte will be the source logical 
address. 
0-12 
Source 
Logical 
Address  
The source logical address specified in the command packet. If source path 
addresses are not used then the source logical address is the address of the 
return packet. 
Protocol 
Identifier  
The RMAP protocol identifier value 01h. 
Command 
Byte  
Write single address reply command byte. The packet type bits in the command 
byte indicate this packet is a reply packet. 
Status  
The command status is returned in this field. The command status can be 
command successful or an RMAP error code as defined in section 7.6.6. 
Destination 
logical 
The destination logical address is set to the default value FEh as the 
SpaceWire router does not have a logical address.