Add isChannelActive() function to radio interface

src/mesh/SX126xInterface.cpp

@@ -226,6 +226,23 @@ void SX126xInterface<T>::startReceive()
 #endif
 }
 
+/** Could we send right now (i.e. either not actively receving or transmitting)? */
+template<typename T>
+bool SX126xInterface<T>::isChannelActive()
+{
+    // check if we can detect a LoRa preamble on the current channel
+    int16_t result;
+
+    setStandby(); 
+    result = lora.scanChannel();
+    if (result == PREAMBLE_DETECTED) 
+        return true;
+    
+    assert(result != ERR_WRONG_MODEM);
+    
+    return false;
+}
+
 /** Could we send right now (i.e. either not actively receving or transmitting)? */
 template<typename T>
 bool SX126xInterface<T>::isActivelyReceiving()