Restoring priority level of output streams to PRIO_BEEP when the stream terminates, made M17Modulator::emitBaseband() wait for effective stream termination before returning when transmission stop is requested. Fixes #76

openrtx/src/protocols/M17/M17Modulator.cpp

@@ -132,10 +132,12 @@ void M17Modulator::emitBaseband()
         outputStream_sync(outStream, true);
     }
 
-    // Check if transmission stop is requested
+    // Check if transmission stop is requested, if so stop the output stream
+    // and wait until its effective termination.
     if(stopTx == true)
     {
         outputStream_stop(outStream);
+        outputStream_sync(outStream, false);
         stopTx     = false;
         txRunning  = false;
         idleBuffer = baseband_buffer;

platform/drivers/audio/outputStream_MDx.cpp

@@ -52,10 +52,11 @@ static inline void stopTransfer()
     // Re-activate "beeps"
     toneGen_unlockBeep();
 
-    // Finally, clear flags
+    // Finally, clear flags and restore priority level
     running      = false;
     reqFinish    = false;
     circularMode = false;
+    priority     = PRIO_BEEP;
 }
 
 /**

platform/drivers/audio/outputStream_Mod17.cpp

@@ -42,7 +42,7 @@ static Thread *dmaWaiting = 0;
  * \internal
  * Stop an ongoing transfer, deactivating timers and DMA stream.
  */
-void stopTransfer()
+static inline void stopTransfer()
 {
     // Stop DMA transfers
     DMA1_Stream5->CR = 0;
@@ -53,10 +53,11 @@ void stopTransfer()
     DAC->CR      = DAC_CR_EN1;     // Keep only channel 1 active
     DAC->DHR12R1 = 1365;           // Set channel 1 (RTX) to about 1.1V when idle
 
-    // Clear flags
+    // Clear flags and restore priority level
     running      = false;
     reqFinish    = false;
     circularMode = false;
+    priority     = PRIO_BEEP;
 }
 
 /**