Data strobe encoding: Difference between revisions

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'''Data strobe encoding''' (or '''D/S''' encoding) is an encoding scheme for transmitting data in [[digital circuit]]s.

It uses two signal lines (e.g. wires in a cable or traces on a [[printed circuit board]]), ''Data'' and ''Strobe''. These have the property that either Data or Strobe changes its [[Truth value|logical value]] in one [[clock cycle]], but never both. More precisely data is transmitted as-is and strobe changes its state if and only if data stays constant between two data bits.

This allows for easy [[clock recovery]] with a good [[jitter]] tolerance by [[XOR]]ing the two signal line values.GOD,<ref>{{cite book |last=Parkes |first=Steve |date=2012 |title=SpaceWire User'''GODs GODGuide GOD|url=https://www.star-dundee.com/wp-content/star_uploads/2019/05/SpaceWire-Users-Guide.pdf GOD|publisher=STAR-Dundee GOD'''''''''Limited |page=52 |isbn=978-0-9573408-0-0 }}</ref>

== ==

There is an equivalent way to specify the relationship between Data and Strobe.

For even-numbered Data bits, Strobe is the opposite of Data.

For odd-numbered Data bits, Strobe is the same as Data.

From this definition it is more obvious that the XOR of Data and Strobe will yield a clock signal. Also, it specifies the simplest means of generating the Strobe signal for a given Data stream.

Data strobe encoding originated in [[IEEE 1355]] Standard and is used on the signal lines in [[SpaceWire]] and the [[FireWire|IEEE 1394]] (also known as [[FireWire 400]]) system.

[[Gray code]] is another code that always changes one logical value, but never more than one.

==References==

{{Reflist}}

[[Category:Line codes]]

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