Add a comment about the polarity of FIFOP.

diff --git a/tos/chips/cc2420/receive/CC2420ReceiveP.nc b/tos/chips/cc2420/receive/CC2420ReceiveP.nc
index 30a421914b9da6a819bfe2e3db99dc92b7ba03c2..b50ad035a36a93e54086eb8bdaee2f68e1489988 100644 (file)
--- a/tos/chips/cc2420/receive/CC2420ReceiveP.nc
+++ b/tos/chips/cc2420/receive/CC2420ReceiveP.nc
@@ -126,6 +126,10 @@ implementation {
       reset_state();
       m_state = S_STARTED;
       atomic receivingPacket = FALSE;
+      /* Note:
+         We use the falling edge because the FIFOP polarity is reversed. 
+         This is done in CC2420Power.startOscillator from CC2420ControlP.nc.
+       */
       call InterruptFIFOP.enableFallingEdge();
     }
     return SUCCESS;