diff --git a/README.md b/README.md
index eb33d1d..da2c343 100644
--- a/README.md
+++ b/README.md
@@ -22,5 +22,5 @@ The buttons are actually diconnected, if you want to test, dive through the code
 
 # Thanks to :
 
-Simon Lothar for his fx-reverse doc
-Cakeisalie5 for his p7 command line tool
\ No newline at end of file
+- Simon Lothar for his fx-reverse doc
+- Cakeisalie5 for his p7 command line tool
\ No newline at end of file
diff --git a/index.js b/index.js
index e55efe3..923d096 100644
--- a/index.js
+++ b/index.js
@@ -1,14 +1 @@
-'use strict'
-/*function test(){
-    throw 'geswg';
-    console.log('err');
-}
-
-
-try {
-    test();
-    console.log('err');
-} catch(err) {
-    console.error(err);
-}*/
-
+'use strict'
\ No newline at end of file
diff --git a/internal.js b/internal.js
index 8578ee5..194e5e9 100644
--- a/internal.js
+++ b/internal.js
@@ -9,7 +9,11 @@ var p7 = {
 };
 
 
+
 (function() {
+  /* ---------------------Global variables--------------------- */
+  var checksumTries = 0;
+
   /* ---------------------Utilitaries--------------------- */
 
   /* Sum individual bytes 
@@ -157,64 +161,85 @@ var p7 = {
 
   p7.receive.packet = async function () {
     console.log("%cReceiving...", "color: orange");
-    let checksumError = 0;
-    let transferInResult = undefined;
+    let transferInResult = undefined; 
+    
     try {
       while (! (transferInResult = await p7.device.transferIn(2, 64)).data.byteLength)
         console.log('The buffer was empty, trying again!');
-
+    
       p7.receiveBuffer.set(new Uint8Array(transferInResult.data.buffer), 0);
     } catch (err) {
       throw new Error("Couldn't receive the first 64 bytes of the packet: " + err.message);
     }
-
-    let packetInfo = {};
-    
+  
+    let packetInfo = {}
     packetInfo.length = 6; /* Type (T), Subtype (S), Extended (EX) and Checksum (CS) fields */
-
+  
     //Set Type (T) field
     packetInfo.type = p7.receiveBuffer[0];
-
+  
     //Set Subtype (ST) field
     packetInfo.subtype = p7.receiveBuffer.slice(1, 2).asciiToHex();
-
+  
     //Set Extended (EX) field
     packetInfo.extended = (p7.receiveBuffer[3] === 0x31);
-
+  
     if (packetInfo.extended) {
       //Set Data size (DS) field
       packetInfo.dataSize = p7.receiveBuffer.slice(4, 8).asciiToHex();
-
+    
       packetInfo.length += packetInfo.dataSize + 4 /* Data size field */;
-
-      let transfered = 0;
-
-      while (transfered < packetInfo.length) {
+    
+      for (let transfered = 64 ; transfered < packetInfo.length ; transfered += 64) {
         try {
           transferInResult = await p7.device.transferIn(2, 64);
         } catch (err) {
           throw new Error("Couldn't receive the " + transfered + "th and following 64 bytes of the packet: " + err.message)
         }
-
-        p7.receiveBuffer.set(new Uint8Array(transferInResult.data.buffer), transfered += 64);
+      
+        p7.receiveBuffer.set(new Uint8Array(transferInResult.data.buffer), transfered);
       }
     }
-    
-    /* Compute checksum */
-    checksumError = ((packetInfo.checksum = p7.receiveBuffer.slice(packetInfo.length - 2, packetInfo.length).asciiToHex()) !== p7.receiveBuffer.slice(1, packetInfo.length - 2).p7Checksum());
 
-    console.log(checksumError);
+    /* Compute checksum */
+    let checksumError = ((packetInfo.checksum = p7.receiveBuffer.slice(packetInfo.length - 2, packetInfo.length).asciiToHex()) !== p7.receiveBuffer.slice(1, packetInfo.length - 2).p7Checksum());
+
+    if (checksumError && (checksumTries++) < 3) {
+      console.log('there was a checksum error');
+      try {
+        packetInfo = await p7.send.packet(p7.make.basicPacket(p7PacketType.error, errorSubtype.resendRequest));
+      } catch (err) {
+        throw new Error("Couldn't send the resend request: " + err.message);
+      }
+    }
+    if (checksumTries === 4)
+      throw new Error("There were three checksum in a row, the calculator or the cable may be broken!");
+    
+    return packetInfo;
   }
 
   /* ---------------------Packet sending--------------------- */
 
-  /* Doesn't work for now on */
   p7.send.packet = async function (length) {
-    try {
-      await p7.device.transferOut(1, p7.sendBuffer.slice(0, length));
-    } catch (err) {
-      throw new Error("Couldn't send the packet: " + err.message);
+    let responsePacketInfo = undefined;
+    let tries = 0;
+    console.log("%cSending packet...", "color: green");
+    for ( ; tries === 0 || (responsePacketInfo.type === p7PacketType.error && responsePacketInfo.subtype === errorSubtype.resendRequest && tries < 3) ; tries++) {
+      try {
+        await p7.device.transferOut(1, p7.sendBuffer.slice(0, length));
+      } catch (err) {
+        throw new Error("Couldn't send the packet: " + err.message);
+      }
+      try {
+        responsePacketInfo = await p7.receive.packet();
+      } catch (err) {
+        throw new Error("Couldn't receive the response packet: " + err.message);
+      }
     }
+    if (tries === 3)
+      throw new Error("Received three resend request in a row, abandon");
+    
+    return responsePacketInfo;
   };
 
   /* ---------------------Initialization and exiting--------------------- */
@@ -362,16 +387,18 @@ var p7 = {
 
     try  {
       await p7.send.packet(p7.make.basicPacket(p7PacketType.check, checkSubtype.initialization));
-      await p7.receive.packet();
     } catch (err) {
-      console.log(err);
+      console.error(err);
+      return err;
     }
 
       
-
-    await p7.send.packet(p7.make.basicPacket(p7PacketType.command, sysCommandSubtype.getDeviceInfo));
-
-    await p7.receive.packet();
+    try {
+      await p7.send.packet(p7.make.basicPacket(p7PacketType.command, sysCommandSubtype.getDeviceInfo));
+    } catch (err) {
+      console.error(err);
+      return err;
+    }
 
     console.log(p7.decode.extendedAckPacket());