Atmel SpaceWire Router SpW-10X - Manual (Page 76)

Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual Date: 11 th
July 2008
Preliminary
76
incrementing read
4. The data length is
not 4 in a verified
write command.
5. The data length is
not 8 in a read
modify write
command.
Invalid Register
Address The address field is
addressing an unknown
register for a read command
or a read only register in a
write command. Yes RMAP Command not
implemented or not
authorised 10
Read Modify
Write Data
Length Error The read modify write data
length is not 8 Yes RMW Data Length Error 11
Invalid
Destination
Logical Address The destination logical
address is invalid. The
destination logical address is
expected to be the default
254 value Yes Invalid Destination
Logical Address
12
7.6.7 Command Packet Cyclic Redundancy Check
The header and data part of an RMAP packet are protected from errors by the use of an 8 bit CRC
code. The header and data CRC is formed using the CRC-8 code used in ATM (Asynchronous
Transfer Mechanism). CRC-8 has the polynomial: 1 1 2 8
+ + +
X X X with a starting value of 00h.
Command packets received by the SpaceWire router which have an invalid header CRC are
discarded and the Invalid Header CRC bit is set in the configuration port register.
7.6.8 Local Source Path Address
The configuration reply packet shall be routed out of the router port the packet arrived on. For
example, if SpaceWire port 1 passed a configuration command to the configuration port then the reply
packet is returned to port 1.