AVL Time State

sequenceDiagram

  participant "Device Time" as SystemTime
  participant "Last saved Time" as LastValidPosition 
  participant "RTC time if RTC available" as RTC 
  participant "GNSS aka GPS time" as GNSS 
  participant "User time" as UserTime 

  autonumber
  SystemTime <- LastValidPosition : load last valid time and timestamp not older then build date
  SystemTime <- RTC : load RTC time if time valid flag and timestamp not older then build date
  ... any time ...
  SystemTime <- GNSS : load GNSS time if time and date valid and timestamp not older then build date
  RTC <- GNSS : set RTC time if time and date valid and timestamp not older then build date
  ... any time ...
  SystemTime <- UserTime : set Time via $PFAL,Sys.SetTime,dd.mm.yy,hh:mm:ss
  RTC <- UserTime : set Time via $PFAL,Sys.SetTime,dd.mm.yy,hh:mm:ss
  ... any time ...
  SystemTime -> LastValidPosition : save last Valid pos and time $PFAL,GPS.Nav.SaveLastValid

TEST

sequenceDiagram
    participant John
    participant Alice
    Alice->>John: Hello John, how are you?
    John-->>Alice: Great!