Add a comment about the polarity of FIFOP.

[tinyos-2.x.git] / tos / chips / cc2420 / receive / CC2420ReceiveP.nc

diff --git a/tos/chips/cc2420/receive/CC2420ReceiveP.nc b/tos/chips/cc2420/receive/CC2420ReceiveP.nc
index 710d0d7e9d4757ccf80b098edf1210352b7ae1ab..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;
@@ -214,7 +218,7 @@ implementation {
         
         if(rxFrameLength <= MAC_PACKET_SIZE) {
           if(rxFrameLength > 0) {
-            if(rxFrameLength >= CC2420_SIZE) {
+            if(rxFrameLength > SACK_HEADER_LENGTH) {
               // This packet has an FCF byte plus at least one more byte to read
               call RXFIFO.continueRead(buf + 1, SACK_HEADER_LENGTH);
               
@@ -334,7 +338,7 @@ implementation {
     metadata->lqi = buf[ length ] & 0x7f;
     metadata->rssi = buf[ length - 1 ];
     
-    if(passesAddressCheck(m_p_rx_buf)) {
+    if (passesAddressCheck(m_p_rx_buf) && length >= CC2420_SIZE) {
       m_p_rx_buf = signal Receive.receive( m_p_rx_buf, m_p_rx_buf->data, 
                                           length - CC2420_SIZE);
     }