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=== Source & Destination Identifiers ===

=== Source & Destination Identifiers ===

The Source & Destination Identifiers, the second and third frames in a Gesture, are 8 bit frames that indicate the source of the Gesture. Each board developed for the HONEY architecture is catalogued and given a unique identifier code. These unique identifiers allow boards to identify who a request or response from, and respond accordingly. Note that each unique board is given a unique identifier -- The Count, the first HONEY-compliant avionics board, has the identifier of 0, but a subsequent revision of avionics would acquire a new identifier code. This allows boards to be aware of the specific revisions that are flying in the stack -- allowing them to dynamically take advantage of the utilities of newer boards as they are added. The identifiers are encoded into the STINGR suite, and one can call a simple function to determine what board was the source or destination, without memorizing or encoding any of these identifiers in local board code.

The Source & Destination Identifiers merit some specific discussion. Boards each have an 8-bit unique Identifier that fully defines that board, and cannot be shared between boards. This allows for a possible 256 HONEY-compliant boards to be used within the STINGR suite. This 8-bit identifier is known as the '''Absolute Board Identifier (ABI)'''.

There is also a unique, reserved designator, which is designator 256 (11111111). This designator is reserved for the broadcast functionality. Gestures with a destination identifier of 256 target ''all'' boards in the stack. That is, if a board wishes to notify all boards in the stack of some particular information, it can do so by designating a destination identifier of 256 -- all boards are configured, via STINGR, to process these gestures, even though the destination identifier isn't their own unique identifier. These are formally referred to as ''broadcast gestures''.  

When a flight stack is constructed and assembled, it ends up being comprised of a series of boards each with one of these unique, enumerated identifiers. It should be noted that a flight stack '''cannot exceed''' 15 boards total (3U). Upon boot-up, the Avionics receives a variety of messages from STINGR identifying all boards in the flight stack, and re-labels the identifiers to the ''Flight Stack Identifiers''' (FSI) format, whereby all 8-bit identifiers are re-categorized and re-assigned into 4-bit stack-relative addresses.  

The following are the current identifier codes, as of writing (June 21, 2017).

 

The following are the current ABI's, as of writing (June 28, 2017).

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