Fixing T32khz to TMilli conversion - coeficient 32 needs to be changed to 28.1.

[tinyos-2.x.git] / tos / chips / cc2420 / packet / CC2420PacketP.nc

diff --git a/tos/chips/cc2420/packet/CC2420PacketP.nc b/tos/chips/cc2420/packet/CC2420PacketP.nc
index 9bca8ae494773663209a225723ed2b9b9282401e..f0c2e3849ba639be9d653fe5b8894f7b85ce5013 100644 (file)
--- a/tos/chips/cc2420/packet/CC2420PacketP.nc
+++ b/tos/chips/cc2420/packet/CC2420PacketP.nc
@@ -38,6 +38,7 @@
 #include "IEEE802154.h"
 #include "message.h"
 #include "CC2420.h"
+#include "CC2420TimeSyncMessage.h"
 
 module CC2420PacketP @safe() {
 
@@ -137,10 +138,13 @@ implementation {
     return call PacketTimeStamp32khz.isValid(msg);
   }
 
+  //timestmap is always represented in 32khz
+  //28.1 is coefficient difference between T32khz and TMilli on MicaZ
   async command uint32_t PacketTimeStampMilli.timestamp(message_t* msg)
   {
-    int32_t offset = call PacketTimeStamp32khz.timestamp(msg) - call LocalTime32khz.get();
-    return (offset >> 5) + call LocalTimeMilli.get();
+    int32_t offset = (call LocalTime32khz.get()-call PacketTimeStamp32khz.timestamp(msg));
+    offset/=28.1;
+    return call LocalTimeMilli.get() - offset;
   }
 
   async command void PacketTimeStampMilli.clear(message_t* msg)
@@ -159,12 +163,18 @@ implementation {
     return ((call CC2420PacketBody.getMetadata( msg ))->timesync);
   }
 
+  //returns offset of timestamp from the beginning of cc2420 header which is
+  //          sizeof(cc2420_header_t)+datalen-sizeof(timesync_radio_t)
+  //uses packet length of the message which is
+  //          MAC_HEADER_SIZE+MAC_FOOTER_SIZE+datalen
   async command uint8_t PacketTimeSyncOffset.get(message_t* msg)
   {
-    // minus 1 because one less byte is transmitted
-    return (call CC2420PacketBody.getHeader(msg))->length - 1 - sizeof(uint32_t);
+    return (call CC2420PacketBody.getHeader(msg))->length
+            + (sizeof(cc2420_header_t) - MAC_HEADER_SIZE)
+            - MAC_FOOTER_SIZE
+            - sizeof(timesync_radio_t);
   }
-
+  
   async command void PacketTimeSyncOffset.set(message_t* msg)
   {
     (call CC2420PacketBody.getMetadata( msg ))->timesync = TRUE;