diff --git a/RFM12B.cpp b/RFM12B.cpp
index 9aca8e4..81810ca 100644
--- a/RFM12B.cpp
+++ b/RFM12B.cpp
@@ -44,6 +44,8 @@ void RFM12B::SPIInit() {
 #endif    
   pinMode(RFM_IRQ, INPUT);
   digitalWrite(RFM_IRQ, 1); // pull-up
+
+  receivedata = NULL; // receivedata callback function set to NULL 
 }
 
 uint8_t RFM12B::Byte(uint8_t out) {
@@ -225,7 +227,8 @@ void RFM12B::InterruptHandler() {
           case TXSYN2: out = networkID; rxstate = -(3 + rf12_len); break;
           case TXCRC1: out = rf12_crc; break;
           case TXCRC2: out = rf12_crc >> 8; break;
-          case TXDONE: XFER(RF_IDLE_MODE); // fall through
+          case TXDONE: XFER(RF_IDLE_MODE); out = 0xAA; break; // fall through
+    case TXIDLE: ReceiveStart(); return; break;  // Restart Receive hardware when done
           default:     out = 0xAA;
         }
         
@@ -263,6 +266,12 @@ void RFM12B::ReceiveStart() {
   XFER(RF_RECEIVER_ON);
 }
 
+void RFM12B::ReceiveCallBack(void (*receivefunction)(void)) {
+
+	receivedata = receivefunction;
+}
+	
+
 bool RFM12B::ReceiveComplete() {
   if (rxstate == TXRECV && (rxfill >= rf12_len + 6 || rxfill >= RF_MAX)) {
     rxstate = TXIDLE;
@@ -273,6 +282,10 @@ bool RFM12B::ReceiveComplete() {
         crypter(false);
       else
         rf12_seq = -1;
+
+      if (receivedata !=NULL) // Callback function if defined
+	receivedata();
+
       return true; // it's a broadcast packet or it's addressed to this node
     }
   }
@@ -295,6 +308,16 @@ bool RFM12B::CanSend() {
   return false;
 }
 
+bool RFM12B::ClearToSend() {
+  // no need to test with interrupts disabled: state TXRECV is only reached
+  // outside of ISR and we don't care if rxfill jumps from 0 to 1 here
+  if (rxstate == TXRECV && rxfill == 0 && (Byte(0x00) & (RF_RSSI_BIT >> 8)) == 0) {
+    return true;
+  }
+  return false;
+}
+
+
 void RFM12B::SendStart(uint8_t toNodeID, bool requestACK, bool sendACK) {
   rf12_hdr1 = toNodeID | (sendACK ? RF12_HDR_ACKCTLMASK : 0);
   rf12_hdr2 = nodeID | (requestACK ? RF12_HDR_ACKCTLMASK : 0);
@@ -309,7 +332,8 @@ void RFM12B::SendStart(uint8_t toNodeID, const void* sendBuf, uint8_t sendLen, b
   rf12_len = sendLen;
   memcpy((void*) rf12_data, sendBuf, sendLen);
   SendStart(toNodeID, requestACK, sendACK);
-  SendWait(waitMode);
+  if (waitMode)
+	  SendWait(waitMode);
 }
 
 /// Should be called immediately after reception in case sender wants ACK
diff --git a/RFM12B.h b/RFM12B.h
index 424a45e..4a8c7f1 100644
--- a/RFM12B.h
+++ b/RFM12B.h
@@ -170,6 +170,7 @@ class RFM12B
   static long rf12_seq;                     // seq number of encrypted packet (or -1)
   static uint8_t cs_pin;                    // chip select pin
   void (*crypter)(bool);                    // does en-/decryption (null if disabled)
+  void (*receivedata)(void);         // Receive callback function
   static uint8_t Byte(uint8_t out);
   static uint16_t XFERSlow(uint16_t cmd);
   static void XFER(uint16_t cmd);
@@ -191,10 +192,12 @@ class RFM12B
     //Defaults: Group: 0xAA=170, transmit power: 0(max), KBPS: 38.3Kbps (air transmission baud - has to be same on all radios in same group)
   	void Initialize(uint8_t nodeid, uint8_t freqBand, uint8_t groupid=0xAA, uint8_t txPower=0, uint8_t airKbps=0x08, uint8_t lowVoltageThreshold=RF12_2v75);
     void SetCS(uint8_t pin);
-    void ReceiveStart();
+    static void ReceiveStart();
     bool ReceiveComplete();
     bool CanSend();
+    bool ClearToSend();
     uint16_t Control(uint16_t cmd);
+    void ReceiveCallBack(void (*receivefunction)(void)); 
     
     void SendStart(uint8_t toNodeId, bool requestACK=false, bool sendACK=false);
     void SendStart(uint8_t toNodeId, const void* sendBuf, uint8_t sendLen, bool requestACK=false, bool sendACK=false, uint8_t waitMode=SLEEP_MODE_STANDBY);
diff --git a/keywords.txt b/keywords.txt
index a430a0f..d27e91d 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -10,11 +10,12 @@
 # Methods and Functions (KEYWORD2)
 #######################################
 Initialize  KEYWORD2
-SetCS	KEYWORD2
+SetCS  KEYWORD2
 Control	KEYWORD2
 ReceiveStart	KEYWORD2
 ReceiveComplete	KEYWORD2
 CanSend	KEYWORD2
+ClearToSend	KEYWORD2
 SendStart	KEYWORD2
 SendACK	KEYWORD2
 SendWait	KEYWORD2
@@ -26,6 +27,7 @@ LowBattery	KEYWORD2
 CryptFunction	KEYWORD2
 Encrypt	KEYWORD2
 CRCPass	KEYWORD2
+ReceiveCallBack	KEYWORD2
 
 #######################################
 # Instances (KEYWORD2)