From 0627e6e9df5fc1648ba98a123b568ae6e9d94112 Mon Sep 17 00:00:00 2001
From: UnKnoWn-Consortium <UnKnoWn-Consortium@users.noreply.github.com>
Date: Sun, 25 Jan 2015 00:07:26 +0000
Subject: [PATCH] Update rfid_default_keys.ino

Updated code to account for serial behavior change in ATMEGA32U4
---
 examples/rfid_default_keys/rfid_default_keys.ino | 1 +
 1 file changed, 1 insertion(+)

diff --git a/examples/rfid_default_keys/rfid_default_keys.ino b/examples/rfid_default_keys/rfid_default_keys.ino
index ea4fe08..16693ef 100644
--- a/examples/rfid_default_keys/rfid_default_keys.ino
+++ b/examples/rfid_default_keys/rfid_default_keys.ino
@@ -53,6 +53,7 @@ byte knownKeys[NR_KNOWN_KEYS][MFRC522::MF_KEY_SIZE] =  {
  */
 void setup() {
     Serial.begin(9600);         // Initialize serial communications with the PC
+    while (!Serial);            // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
     SPI.begin();                // Init SPI bus
     mfrc522.PCD_Init();         // Init MFRC522 card
     Serial.println("Try the most used default keys to print block 0 of a MIFARE PICC.");