add Troubleshooting to README

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?**
+
+  1. Check your connection, see `Pin Layout`_ .
+  2. Check voltage. Most breakouts work with 3.3V.
+  3. 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.**
+
+  1. Try other site of the antenna.
+  2. Try to decrease distance between MFRC522.
+  3. Increase antenna gain per firmware: ``mfrc522.PCD_SetAntennaGain(mfrc522.RxGain_max);``
+  4. Use better power supply.
+  5. Hardware corrupted, most products are from china and sometimes the quality is really low. Contact your seller.
+  
+  
+* **My tag/card doesn't work.**
+  
+  1. Distance between antenna and token too huge (>1cm).
+  2. You got wrong PICC. Is it really 13.56MGhz? Is it really a Mifare Type A?
+  3. NFC tokens are not supported. Some may work.
+  4. Animal marker are not supported. They use other frequency.
+  5. 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**
+
+  1. Card simmulation is not supported.
+  2. Communication with mobile phones is not supported.
+  3. Peer to peer communication is not supported.
+  
+* **I need more features.**
+
+  1. If software: code it and make a pull request.
+  2. 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.