Atmel SpW-10X SpaceWire Router, User Manual, Preliminary, Data Length MS, Data Length LS, Command

		SpW-10X	Ref.:	UoD_SpW-10X_
		SpaceWire Router		UserManual
			Issue:	3.4
		User Manual
			Date:	11th July 2008
Length	one 32 bit register location.
Header	The header CRC is the eight bit CRC code used to detect errors in the				1
CRC	command packet. The CRC code is checked before the command is
	executed

In Figure 7-4 the format of the reply to a read single address 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.

First byte transmitted

Source Path Address

Source Path Address

Source Path Address

Source Logical Address

Protocol Identifier

Packet Type, Command,

Status

01h

Source Path Addr Len

Destination Logical Address

Transaction Identifier (MS)

Transaction Identifier (LS)

Reserved = 0

FEh

Data Length (MS)

Data Length

Data Length (LS)

Header CRC

00h

00h

04h

Data (Word 0 MSB)

Data

Data

Data (Word 0 LSB)

Data CRC

EOP

Last byte transmitted

Bits in Packet Type / Command / Source Address Path Length Byte

MSB

LSB

0

0

0

0

1

0

Source Path

Source Path

Address Length

Address Length

Packet Type

Command

Source Path Address Length

Figure 7-4 Read Single Address Reply Packet Format

Table 7-7 Read Single Address Reply Packet Fields

Field

Description

Bytes

Source

Optional source path addresses specified in the command packet. If no source

>=0

Path

path addresses are specified then the first byte will be the source logical

Address

address.

Source

The source logical address specified in the command packet. If source path

1

Logical

addresses are not used then the source logical address is the address of the

Address

return packet.

Preliminary

59