Atmel SpaceWire Router SpW-10X - Manual (Page 66)

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