fix for back-to-back issue

src/Meshcore.php

@@ -282,11 +282,24 @@ class Meshcore {
      */
     public function sendBinaryRequest(string $request): mixed {
         CoreProtocol::writeFrame($this->serial, chr(CoreProtocol::CMD_SEND_BINARY_REQ) . $request);
-        $response = CoreProtocol::readFrame($this->serial);
+
+        do {
+            $response = CoreProtocol::readFrame($this->serial);
+
+        }
+        while(
+            ord($response) != CoreProtocol::RESP_CODE_SENT && 
+            ord($response) != CoreProtocol::ERR_CODE_NOT_FOUND &&
+            ord($response) != CoreProtocol::ERR_CODE_NOT_FOUND
+        );
 
         return CoreParser::parseResponse($response);     
     }
 
+    public function readFrame(): mixed {
+        return CoreProtocol::readFrame($this->serial);
+    }
+
     /**
      * 
      * @param string $tag 
@@ -305,7 +318,7 @@ class Meshcore {
 
             usleep(500000);
         }
-        while( (time() - $mark) < $timeout_ms );
+        while( ((time() - $mark) * 1000) < $timeout_ms );
 
         return false;
     }