GPS Time Sync Functionality

[ryanpdx]

GPS Time Sync overview

• C3 clears all of the old GPS data in the Object Dictionary (OD).
• GPS PNT worker thread is started on C3 boot up.
• Thread delays 4 hours after start (OD configurable)
• Turn on the GPS card using the node manager
  • Heartbeat delay should be long enough for boot - like 60 seconds?
  • Node manager will try to restart the GPS card three times if it doesn’t get a heartbeat
• C3 waits for GPS app to start sending data
  • ~1 minute for “not locked” messages to start.
  • ~ 5 minutes, but maybe even ~15 minutes, for GPS to lock and “locked” messages to be sent.
• After 20 minutes of “not locked”, C3 should power down GPS and declare failure.
• GPS automatically broadcasts TPDO of the lock state once a second.
• GPS automatically broadcasts TPDOs of PNT data when locked
• C3 checks the OD to see if the GPS is locked (to see if a GPS TPDO has been received that says it’s locked).
• If locked, C3 sends the CANopen SYNC command
  • GPS responds with the time sync TPDO.
  • Everyone who’s listening, like the C3, updates their clock.
• After a successful time sync
  • Shutdown GPS card
• Thread goes to sleep and waits for next wakeup.