Merge pull request #105 from Rotzbua/master

add Troubleshooting to README

MFRC522.cpp

@@ -1141,6 +1141,7 @@ byte MFRC522::PCD_MIFARE_Transceive(	byte *sendData,		///< Pointer to the data t
 /**
  * Returns a __FlashStringHelper pointer to a status code name.
  * 
+ * @return const __FlashStringHelper *
  */
 const __FlashStringHelper *MFRC522::GetStatusCodeName(byte code	///< One of the StatusCode enums.
 										) {
@@ -1194,6 +1195,7 @@ byte MFRC522::PICC_GetType(byte sak		///< The SAK byte returned from PICC_Select
 /**
  * Returns a __FlashStringHelper pointer to the PICC type name.
  * 
+ * @return const __FlashStringHelper *
  */
 const __FlashStringHelper *MFRC522::PICC_GetTypeName(byte piccType	///< One of the PICC_Type enums.
 										) {

README.rst

@@ -91,6 +91,46 @@ Protocols
     
   * The reader do not support ISO/IEC 14443-3 Type B.
 
+
+Troubleshooting
+-------
+
+* **I don't get input from reader** or **WARNING: Communication failure, is the MFRC522 properly connected?**
+
+  #. Check your connection, see `Pin Layout`_ .
+  #. Check voltage. Most breakouts work with 3.3V.
+  #. The SPI only works with 3.3V, most breakouts seems 5V tollerant, but try a level shifter.
+
+
+* **Sometimes I get timeouts** or **tag/card sometimes not work.**
+
+  #. Try other site of the antenna.
+  #. Try to decrease distance between MFRC522.
+  #. Increase antenna gain per firmware: ``mfrc522.PCD_SetAntennaGain(mfrc522.RxGain_max);``
+  #. Use better power supply.
+  #. Hardware corrupted, most products are from china and sometimes the quality is really low. Contact your seller.
+  
+  
+* **My tag/card doesn't work.**
+  
+  #. Distance between antenna and token too huge (>1cm).
+  #. You got wrong PICC. Is it really 13.56MGhz? Is it really a Mifare Type A?
+  #. NFC tokens are not supported. Some may work.
+  #. Animal marker are not supported. They use other frequency.
+  #. Hardware corrupted, most products are from china and sometimes the quality is really low. Contact your seller.
+
+* **My mobile phone doesn't recognize the MFRC522** or **my MFRC522 can't read data from other MFRC522**
+
+  #. Card simmulation is not supported.
+  #. Communication with mobile phones is not supported.
+  #. Peer to peer communication is not supported.
+  
+* **I need more features.**
+
+  #. If software: code it and make a pull request.
+  #. If hardware: buy a more expensive like PN532 (supports NFC and many more, but costs about $15)
+  
+  
 License
 -------
 This is free and unencumbered software released into the public domain.