diff --git a/DFRobotDFPlayerMini.cpp b/DFRobotDFPlayerMini.cpp
index 0eac2d5..672087f 100644
--- a/DFRobotDFPlayerMini.cpp
+++ b/DFRobotDFPlayerMini.cpp
@@ -34,7 +34,7 @@ void DFRobotDFPlayerMini::sendStack(){
   if (_sending[Stack_ACK]) {  //if the ack mode is on wait until the last transmition
     while (_isSending) {
       delay(0);
-      waitAvailable();
+      waitSending();
     }
   }
 
@@ -50,7 +50,7 @@ void DFRobotDFPlayerMini::sendStack(){
   _serial->write(_sending, DFPLAYER_SEND_LENGTH);
   _timeOutTimer = millis();
   _isSending = _sending[Stack_ACK];
-  
+
   if (!_sending[Stack_ACK]) { //if the ack mode is off wait 10 ms after one transmition.
     delay(10);
   }
@@ -95,16 +95,30 @@ bool DFRobotDFPlayerMini::waitAvailable(unsigned long duration){
   return true;
 }
 
+bool DFRobotDFPlayerMini::waitSending(unsigned long duration){
+  unsigned long timer = millis();
+  if (!duration) {
+    duration = _timeOutDuration;
+  }
+  while (!available() && _isSending){
+    if (millis() - timer > duration) {
+      return handleError(TimeOut);
+    }
+    delay(0);
+  }
+  return true;
+}
+
 bool DFRobotDFPlayerMini::begin(Stream &stream, bool isACK, bool doReset){
   _serial = &stream;
-  
+
   if (isACK) {
     enableACK();
   }
   else{
     disableACK();
   }
-  
+
   if (doReset) {
     reset();
     waitAvailable(2000);
@@ -153,7 +167,7 @@ void DFRobotDFPlayerMini::parseStack(){
     _isSending = false;
     return;
   }
-  
+
   _handleCommand = handleCommand;
   _handleParameter =  arrayToUint16(_received + Stack_Parameter);
 
@@ -280,8 +294,8 @@ bool DFRobotDFPlayerMini::available(){
       _receivedIndex++;
     }
   }
-  
-  
+
+
   return _isAvailable;
 }
 
@@ -452,7 +466,7 @@ int DFRobotDFPlayerMini::readFileCounts(uint8_t device){
     default:
       break;
   }
-  
+
   if (waitAvailable()) {
     if (readType() == DFPlayerFeedBack) {
       return read();
diff --git a/DFRobotDFPlayerMini.h b/DFRobotDFPlayerMini.h
index 32c4787..7593fc9 100644
--- a/DFRobotDFPlayerMini.h
+++ b/DFRobotDFPlayerMini.h
@@ -67,13 +67,13 @@
 
 class DFRobotDFPlayerMini {
   Stream* _serial;
-  
+
   unsigned long _timeOutTimer;
   unsigned long _timeOutDuration = 500;
-  
+
   uint8_t _received[DFPLAYER_RECEIVED_LENGTH];
   uint8_t _sending[DFPLAYER_SEND_LENGTH] = {0x7E, 0xFF, 06, 00, 01, 00, 00, 00, 00, 0xEF};
-  
+
   uint8_t _receivedIndex=0;
 
   void sendStack();
@@ -81,121 +81,123 @@ class DFRobotDFPlayerMini {
   void sendStack(uint8_t command, uint16_t argument);
   void sendStack(uint8_t command, uint8_t argumentHigh, uint8_t argumentLow);
 
+  bool waitSending(unsigned long duration = 0);
+
   void enableACK();
   void disableACK();
-  
+
   void uint16ToArray(uint16_t value,uint8_t *array);
-  
+
   uint16_t arrayToUint16(uint8_t *array);
-  
+
   uint16_t calculateCheckSum(uint8_t *buffer);
-  
+
 
 
   void parseStack();
   bool validateStack();
-  
+
   uint8_t device = DFPLAYER_DEVICE_SD;
-  
+
   public:
-  
+
   uint8_t _handleType;
   uint8_t _handleCommand;
   uint16_t _handleParameter;
   bool _isAvailable = false;
   bool _isSending = false;
-  
+
   bool handleMessage(uint8_t type, uint16_t parameter = 0);
   bool handleError(uint8_t type, uint16_t parameter = 0);
 
   uint8_t readCommand();
-  
+
   bool begin(Stream& stream, bool isACK = true, bool doReset = true);
-  
+
   bool waitAvailable(unsigned long duration = 0);
-  
+
   bool available();
-  
+
   uint8_t readType();
-  
+
   uint16_t read();
-  
+
   void setTimeOut(unsigned long timeOutDuration);
-  
+
   void next();
-  
+
   void previous();
-  
+
   void play(int fileNumber=1);
-  
+
   void volumeUp();
-  
+
   void volumeDown();
-  
+
   void volume(uint8_t volume);
-  
+
   void EQ(uint8_t eq);
-  
+
   void loop(int fileNumber);
-  
+
   void outputDevice(uint8_t device);
-  
+
   void sleep();
-  
+
   void reset();
-  
+
   void start();
-  
+
   void pause();
-  
+
   void playFolder(uint8_t folderNumber, uint8_t fileNumber);
-  
+
   void outputSetting(bool enable, uint8_t gain);
-  
+
   void enableLoopAll();
-  
+
   void disableLoopAll();
-  
+
   void playMp3Folder(int fileNumber);
-  
+
   void advertise(int fileNumber);
-  
+
   void playLargeFolder(uint8_t folderNumber, uint16_t fileNumber);
-  
+
   void stopAdvertise();
-  
+
   void stop();
-  
+
   void loopFolder(int folderNumber);
-  
+
   void randomAll();
-  
+
   void enableLoop();
-  
+
   void disableLoop();
-  
+
   void enableDAC();
-  
+
   void disableDAC();
-  
+
   int readState();
-  
+
   int readVolume();
-  
+
   int readEQ();
-  
+
   int readFileCounts(uint8_t device);
-  
+
   int readCurrentFileNumber(uint8_t device);
-  
+
   int readFileCountsInFolder(int folderNumber);
-  
+
   int readFileCounts();
 
   int readFolderCounts();
-  
+
   int readCurrentFileNumber();
-  
+
 };
 
 #endif