Patch incorporate changes on CVS head through 8/23/09 for tos/lib/ftsp only.

[tinyos-2.x.git] / tos / lib / ftsp / TimeSyncMsg.h

diff --git a/tos/lib/ftsp/TimeSyncMsg.h b/tos/lib/ftsp/TimeSyncMsg.h
index a9e6e393e57c5a3e250f2e545fea7a319fda2cb0..f45c2b346f68aa5da56be9b38f2d833f1b5fb66c 100644 (file)
--- a/tos/lib/ftsp/TimeSyncMsg.h
+++ b/tos/lib/ftsp/TimeSyncMsg.h
@@ -32,10 +32,16 @@ typedef nx_struct TimeSyncMsg
        nx_uint16_t     nodeID;         // the node if of the sender
        nx_uint8_t      seqNum;         // sequence number for the root
 
-       /* This field is initially set to the offset between global time and local
-        * time. The TimeStamping component will add the current local time when the
-        * message is actually transmitted. Thus the receiver will receive the
-        * global time of the sender when the message is actually sent. */
+       /*
+       * After TEP 133, the message timestamp contains the difference between
+       * event time and the time the message was actually sent out. TimeSyncP
+       * sends the local time associated with this globalTime to the
+       * TimeStamping mechanism, which then calculates the difference.
+       *
+       * On the receiving side, the difference is applied to the local
+       * timestamp. The receiving timestamp thus represents the time on the
+       * receiving clock when the remote globalTime was taken.
+       */
        nx_uint32_t     globalTime;
 
        //just for convenience