diff --git a/app/src/main/java/fr/mobdev/lpcprog/fragment/FlashFragment.java b/app/src/main/java/fr/mobdev/lpcprog/fragment/FlashFragment.java
index 081ca1b..c4beff2 100644
--- a/app/src/main/java/fr/mobdev/lpcprog/fragment/FlashFragment.java
+++ b/app/src/main/java/fr/mobdev/lpcprog/fragment/FlashFragment.java
@@ -261,6 +261,7 @@ public class FlashFragment extends Fragment{
                                 Button bt = v.findViewById(R.id.retry_isp_mode);
                                 bt.setVisibility(View.VISIBLE);
                                 flash_infoStr += getString(R.string.fail) + "\n";
+                                flash_infoStr += getString(R.string.try_isp_again)+"\n";
                                 flash_info.setText(flash_infoStr);
                             } else {
                                 View v = getView();
diff --git a/app/src/main/java/fr/mobdev/lpcprog/managers/IspManager.java b/app/src/main/java/fr/mobdev/lpcprog/managers/IspManager.java
index 711d25c..2dc5c5a 100644
--- a/app/src/main/java/fr/mobdev/lpcprog/managers/IspManager.java
+++ b/app/src/main/java/fr/mobdev/lpcprog/managers/IspManager.java
@@ -113,12 +113,13 @@ public class IspManager {
         return true;
     }
 
-    private void clearBuffer(int size) {
+    private int clearBuffer(int size) {
         if (serialPort == null)
-            return;
+            return -1;
 
         byte[] buf = new byte[size];
-        read(buf, size, 500);
+        int ret = read(buf, size, 1000);
+        return ret;
     }
 
     public String[] readUid() {
@@ -299,8 +300,16 @@ public class IspManager {
     private boolean synchronize(int crystal_freq) {
         if (serialPort == null)
             return false;
+        int cpt = 0;
+        while(clearBuffer(1000) > 0 && cpt < 20)
+        {
+            cpt++;
+        }
         serialPort.purge(D2xxManager.FT_PURGE_RX);
         serialPort.purge(D2xxManager.FT_PURGE_TX);
+        if(cpt == 20) {
+            return false;
+        }
         byte[] buf;
         if (serialPort.write(SYNC_START) != SYNC_START.length) {
             return false;
@@ -500,6 +509,7 @@ public class IspManager {
 
     private int parseRetCode(byte[] data) {
         String str = new String(data,0,2);
+        str.replace(" ","");
         str = str.replace("\r", "");
         str = str.replace("\n", "");
         if (!str.matches("[0-9 -+]*")||str.isEmpty())
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 5f39764..14c2e1c 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -88,6 +88,7 @@
     <string name="download_binary">Download Binary</string>
     <string name="informations">Informations</string>
     <string name="no_device">No Device Pluggued, please plug one to be able to flash a binary on it.</string>
+    <string name="try_isp_again">Please try to reset your device in ISP Mode again</string>
     <array name="uuencode_array">
         <item>Yes</item>
         <item>No</item>