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 876b1243656c637dad7f62a71728391e9dd9671c..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;
@@ -326,16 +330,17 @@ implementation {
   task void receiveDone_task() {
     cc2420_metadata_t* metadata = call CC2420PacketBody.getMetadata( m_p_rx_buf );
     cc2420_header_t* header = call CC2420PacketBody.getHeader( m_p_rx_buf);
+    uint8_t length = header->length;
     uint8_t tmpLen __DEPUTY_UNUSED__ = sizeof(message_t) - (offsetof(message_t, data) - sizeof(cc2420_header_t));
     uint8_t* COUNT(tmpLen) buf = TCAST(uint8_t* COUNT(tmpLen), header);
     
-    metadata->crc = buf[ rxFrameLength ] >> 7;
-    metadata->lqi = buf[ rxFrameLength ] & 0x7f;
-    metadata->rssi = buf[ rxFrameLength - 1 ];
+    metadata->crc = buf[ length ] >> 7;
+    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, 
-          rxFrameLength );
+                                          length - CC2420_SIZE);
     }
     
     atomic receivingPacket = FALSE;