Ref.:
UoD_SpW-10X_
UserManual
Issue:
3.4
SpW-10X
SpaceWire Router
User Manual
Date:
11
th
July 2008
Preliminary
66
32-bit read-modify-write
S
4
No
64-bit read-modify-write
NS
-
-
Word or byte address
32-bit aligned
Accepted Logical Addresses
0xFE
Accepted destination keys
0x20 at power on
Accepted address ranges
0x00 0000 0000 – 0x00 0000 0109
Incrementing address
No
The RMAP read-modify-write command is supported by the SpaceWire router. The read modify write
command is used to set or reset a single or number of bits in a router register. The Read-Modify-Write
command is useful when it is desirable to set a link register setting without upsetting the other settings
in one command, i.e. set the start bit without modifying the data rate.
In Figure 7-7 the first byte received 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.
Destination Logical Address
FEh
Protocol Identifier
01h
Packet Type, Command
Source Path Addr Len
Destination Key
Source Path Address
Source Path Address
Source Path Address
Source Path Address
Source Logical Address
Transaction Identifier (MS)
Transaction Identifier (LS)
Extended RMW Address
00h
RMW Address (MS)
00h
RMW Address
00h
RMW Address
RMW Address (LS)
Data +Mask Length (MS)
00h
Data + Mask Length
00h
Data + Mask Length (LS)
08h
Header CRC
Data (MS)
Data
Data
Data (LS)
Config Port Address
00h
Data/Mask CRC
EOP
First byte transmitted
Last byte transmitted
0
1
1
1
1
0
Bits in Packet Type / Command / Source Address Path Length Byte
MSB
Packet Type
Command
Mask (MS)
Mask
Mask
Mask (LS)
Source Path
Address Length
Source Path
Address Length
LSB
Source Path Address Length
Figure 7-7 Read-Modify-Write Command Packet Format