Improve recovery after NFC comms failure

main.py

@@ -124,13 +124,19 @@ def reader_thread(card_data_queue):
             with open(TEST_PIPE, 'r') as pipe:
                success, card = (True, pipe.readline())
         else:
+            nfc.SAMConfig()
             success, card = nfc.readPassiveTargetID(pn532.PN532_MIFARE_ISO14443A_106KBPS)
 
+        if not TEST:
             try:
                 # ensure we have communication with the reader
                 if nfc.getFirmwareVersion():
                     feed_watchdog()
+                else:
+                    raise
             except:
+                logging.error('Problem communicating with NFC reader!')
+                time.sleep(1)
                 continue
 
         try: