Index: firmware/App/Services/CommBuffers.c
===================================================================
diff -u -r1bbf9da32e622975efed00b1a7589387a9829440 -rf7e3018ec6ab762fe08efb42b21fb2ca970174b0
--- firmware/App/Services/CommBuffers.c	(.../CommBuffers.c)	(revision 1bbf9da32e622975efed00b1a7589387a9829440)
+++ firmware/App/Services/CommBuffers.c	(.../CommBuffers.c)	(revision f7e3018ec6ab762fe08efb42b21fb2ca970174b0)
@@ -1,6 +1,6 @@
 /**************************************************************************
  *
- *  Copyright (c) 2019-2019 Diality Inc. - All Rights Reserved.
+ *  Copyright (c) 2019-2020 Diality Inc. - All Rights Reserved.
  *
  *  THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
  *  WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
@@ -32,9 +32,10 @@
 
 // ********** private data **********
 
-static U32 commBufferByteCount[ NUM_OF_COMM_BUFFERS ][ DOUBLE_BUFFERS ];               // for each buffer, how many bytes does it contain?  (also index to next available)
-static U32 activeDoubleBuffer[ NUM_OF_COMM_BUFFERS ];                                  // for each buffer, which double buffer is being fed right now?
+static volatile U32 commBufferByteCount[ NUM_OF_COMM_BUFFERS ][ DOUBLE_BUFFERS ];      // for each buffer, how many bytes does it contain?  (also index to next available)
+static volatile U32 activeDoubleBuffer[ NUM_OF_COMM_BUFFERS ];                         // for each buffer, which double buffer is being fed right now?
 static U08 commBuffers[ NUM_OF_COMM_BUFFERS ][ DOUBLE_BUFFERS ][ COMM_BUFFER_LENGTH ]; // each is double buffered to avoid thread contention
+static volatile BOOL bufferGetLock[ NUM_OF_COMM_BUFFERS ];                             // prevent getter from accessing active buffer while add in progress
 
 // ********** private function prototypes **********
 
@@ -96,6 +97,7 @@
 
         // add requires brief thread protection because there may be multiple sources for transmits trying to add data to a buffer.
         _disable_IRQ();
+        bufferGetLock[ buffer ] = TRUE;
 
         activeBuffer = activeDoubleBuffer[ buffer ];
         currentActiveBufCount = commBufferByteCount[ buffer ][ activeBuffer ];
@@ -105,20 +107,22 @@
         {
             U08 *buffPtr;  // buffer destination for added data
 
-            // adjust buffer count per this data add (also reserves space to add data before releasing thread protection)
-            commBufferByteCount[ buffer ][ activeBuffer ] += len;
-            // release thread protection
-            _enable_IRQ();
             // set destination pointer to end of active buffer data
             buffPtr = &commBuffers[ buffer ][ activeBuffer ][ currentActiveBufCount ];
             // copy source data to destination buffer
             memcpy( buffPtr, data, len );
+            // adjust buffer count per this data add (also reserves space to add data before releasing thread protection)
+            commBufferByteCount[ buffer ][ activeBuffer ] += len;
+            // release thread protection
+            bufferGetLock[ buffer ] = FALSE;
+            _enable_IRQ();
             // data successfully added to buffer
             result = TRUE;
         }
         else // buffer too full to add this much data
         {
             // release thread protection
+            bufferGetLock[ buffer ] = FALSE;
             _enable_IRQ();
             SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_ADD_TOO_MUCH_DATA, len )
         }
@@ -156,7 +160,7 @@
     // verify given buffer
     if ( buffer < NUM_OF_COMM_BUFFERS )
     {
-        // verify size of get
+        // verify requested # of bytes to get are in the buffer
         if ( ( len <= ( COMM_BUFFER_LENGTH * DOUBLE_BUFFERS ) ) && ( len <= numberOfBytesInCommBuffer( buffer ) ) )
         {
             U32 activeBuffer = activeDoubleBuffer[ buffer ];
@@ -179,10 +183,6 @@
                 result += remNumOfBytes;
             }
         }
-        else // invalid get size given
-        {
-            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_GET_TOO_MUCH_DATA, len )
-        }
     }
     else // invalid buffer given
     {
@@ -215,7 +215,7 @@
     // verify given buffer
     if ( buffer < NUM_OF_COMM_BUFFERS )
     {
-        // verify size of peek
+        // verify requested # of bytes to peek are in the buffer
         if ( ( len <= ( COMM_BUFFER_LENGTH * DOUBLE_BUFFERS ) ) && ( len <= numberOfBytesInCommBuffer( buffer ) ) )
         {
             U32 activeBuffer = activeDoubleBuffer[ buffer ];
@@ -237,10 +237,6 @@
                 numOfBytesPeeked = bytesInInactiveBuffer + remNumOfBytes;
             }
         }
-        else // invalid peek size given
-        {
-            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_PEEK_TOO_MUCH_DATA, len )
-        }
     }
     else // invalid buffer given
     {
@@ -268,7 +264,17 @@
     // verify given buffer
     if ( buffer < NUM_OF_COMM_BUFFERS )
     {
-        result = commBufferByteCount[ buffer ][ 0 ] + commBufferByteCount[ buffer ][ 1 ];
+        U32 activeBuffer = activeDoubleBuffer[ buffer ];
+        U32 inactiveBuffer = GET_TOGGLE( activeBuffer, 0, 1 );
+
+        if ( FALSE == bufferGetLock[ buffer ] )
+        {
+            result = commBufferByteCount[ buffer ][ inactiveBuffer ] + commBufferByteCount[ buffer ][ activeBuffer ];
+        }
+        else
+        {
+            result = commBufferByteCount[ buffer ][ inactiveBuffer ];
+        }
     }
     else // invalid buffer
     {