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GR740
13.5.4 SpaceWire Plug-and-Play interface
The configuration port supports parts of the SpaceWire Plug-and-Play protocol [SPWPNP]. The sup-
ported fields are listed in table 209, and explained in more detail in tables 210 through 224.
The SpaceWire Plug-and-Play protocol uses standard RMAP commands and replies with the same
requirements as presented in section 13.5.1, but with the following differences:
• Protocol Identifier field of a command shall be set to 0x03.
• A command’s address fields shall contain a word address. The SpaceWire Plug-and-Play
addresses are encoded as shown in table 207.
• The increment bit in the command’s instruction field shall be set to 1, otherwise a reply with Sta-
tus field set to 0x0A (authorization failure) is sent.
• RMAP Read-modify-write command is replaced by a compare-and-swap operation. The com-
mand’s data fields shall contain the new data to be written, while the mask fields shall contain the
value that the current data must match in order for the new data to be written. If there is a mis-
match, a reply with Status field set to 0x0A (authorization failure) is sent.
• The reply packet’s Status field can contain the additional status codes described in table 208.
Note that it is not possible to access the SpaceWire Plug-and-Play fields through the AHB slave inter-
face, except for the fields that are double mapped into the configuration port’s address space (see sec-
tion 13.5.3).
An access (read, write, or compare-and-swap) made either to a field outside the Device Information
service, or to a field in an undefined field set within the Device Information service, will generate a
reply with the Status field set to 0xF1. An access (read, write, or compare-and-swap) to an undefined
or unsupported field in one of the defined field sets, within the Device Information service, is not
Table 207. SpaceWire Plug-and-Play address encoding
31 24 23 19 18 14 13 0
Application Index Protocol Index FieldSet ID Field ID
Table 208. SpaceWire Plug-and-Play status codes
Value Description
0xF0 Unauthorized access - A write, or compare-and-swap command arrived either when the router was
not configured (Device ID field = 0), or the command did not match the owner information saved in
the Link Information field and Owner Address fields.
0xF1 Reserved field set - A read, write, or compare-and-swap command’s address field points to a non
existing field set.
0xF2 Read-only field - A write, or compare-and-swap command’s address points to a read-only field.
0xF3 Compare-and-swap-only-field - A write command’s address points to a compare-and-swap-only
field.
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