Chronometer

I noticed some while ago a video from Karl demonstrating a working chronometer . I am at a stage of building a pair and asking if anyone has been here and if so setting up the two displays in mobiflight , Zulu time and flight timer. Research so far is mobiflight may deal with Zulu time but timer may have to be set up via alternative Arduino script ?, any help from you guys or girls would be very welcome !!. Thank You Andy