Atmel SpW-10X user manual Preliminary66, SpaceWire Router, User Manual, Config Port Address

		SpW-10X		Ref.: UoD_SpW-10X_
		SpaceWire Router				UserManual
				Issue:		3.4
		User Manual
				Date:		11th July 2008
					No
32-bit read-modify-write	S		4
					-
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.

First byte transmitted

									Config Port Address
									00h
Destination Logical Address			Protocol Identifier			Packet Type, Command			Destination Key
	FEh			01h		Source Path Addr Len
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)			RMW Address			RMW Address			RMW Address (LS)
	00h			00h
Data +Mask Length (MS)			Data + Mask Length			Data + Mask Length (LS)			Header CRC
	00h			00h			08h
	Data (MS)			Data			Data		Data (LS)
	Mask (MS)			Mask			Mask		Mask (LS)
Data/Mask CRC			EOP
Last byte transmitted
Bits in Packet Type / Command / Source Address Path Length Byte
MSB											LSB
0		1	0		1	1		1	Source Path	Source Path
									Address Length	Address Length
	Packet Type				Command				Source Path Address Length

Figure 7-7 Read-Modify-Write Command Packet Format

Preliminary66