X-Git-Url: https://oss.titaniummirror.com/gitweb/?a=blobdiff_plain;f=tos%2Fchips%2Fcc2420%2Ftransmit%2FCC2420TransmitP.nc;h=a8367e54c99f0342df952fd65fda1dc59baf2e5c;hb=fbde8e8b590651b32583d9250bb4921d5b6ab1a3;hp=5e45f8d769ae85f345f5db511eeba0c7b12f65a3;hpb=31bef23ef3377514af595000d2fa2cce07bd4531;p=tinyos-2.x.git

diff --git a/tos/chips/cc2420/transmit/CC2420TransmitP.nc b/tos/chips/cc2420/transmit/CC2420TransmitP.nc
index 5e45f8d7..a8367e54 100644
--- a/tos/chips/cc2420/transmit/CC2420TransmitP.nc
+++ b/tos/chips/cc2420/transmit/CC2420TransmitP.nc
@@ -257,6 +257,7 @@ implementation {
    */
   async event void CaptureSFD.captured( uint16_t time ) {
     uint32_t time32;
+    uint8_t sfd_state = 0;
     atomic {
       time32 = getTime32(time);
       switch( m_state ) {
@@ -264,6 +265,9 @@ implementation {
       case S_SFD:
         m_state = S_EFD;
         sfdHigh = TRUE;
+        // in case we got stuck in the receive SFD interrupts, we can reset
+        // the state here since we know that we are not receiving anymore
+        m_receiving = FALSE;
         call CaptureSFD.captureFallingEdge();
         call PacketTimeStamp.set(m_msg, time32);
         if (call PacketTimeSyncOffset.isSet(m_msg)) {
@@ -274,6 +278,8 @@ implementation {
            call CSN.clr();
            call TXFIFO_RAM.write( absOffset, (uint8_t*)timesync, sizeof(timesync_radio_t) );
            call CSN.set();
+           //restoring the event time to the original value
+           *timesync  += time32;
         }
 
         if ( (call CC2420PacketBody.getHeader( m_msg ))->fcf & ( 1 << IEEE154_FCF_ACK_REQ ) ) {
@@ -305,9 +311,12 @@ implementation {
         /** Fall Through because the next interrupt was already received */
         
       default:
+        /* this is the SFD for received messages */
         if ( !m_receiving && sfdHigh == FALSE ) {
           sfdHigh = TRUE;
           call CaptureSFD.captureFallingEdge();
+          // safe the SFD pin status for later use
+          sfd_state = call SFD.get();
           call CC2420Receive.sfd( time32 );
           m_receiving = TRUE;
           m_prev_time = time;
@@ -315,13 +324,23 @@ implementation {
             // wait for the next interrupt before moving on
             return;
           }
+          // if SFD.get() = 0, then an other interrupt happened since we
+          // reconfigured CaptureSFD! Fall through
         }
         
         if ( sfdHigh == TRUE ) {
           sfdHigh = FALSE;
           call CaptureSFD.captureRisingEdge();
           m_receiving = FALSE;
-          if ( time - m_prev_time < 10 ) {
+          /* if sfd_state is 1, then we fell through, but at the time of
+           * saving the time stamp the SFD was still high. Thus, the timestamp
+           * is valid.
+           * if the sfd_state is 0, then either we fell through and SFD
+           * was low while we safed the time stamp, or we didn't fall through.
+           * Thus, we check for the time between the two interrupts.
+           * FIXME: Why 10 tics? Seams like some magic number...
+           */
+          if ((sfd_state == 0) && (time - m_prev_time < 10) ) {
             call CC2420Receive.sfd_dropped();
             if (m_msg)
               call PacketTimeStamp.clear(m_msg);