Improve recovery after NFC comms failure

main.py

@@ -124,14 +124,20 @@ 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)
 
-        try:
-            # ensure we have communication with the reader
-            if nfc.getFirmwareVersion():
-                feed_watchdog()
-        except:
-            continue
+        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:
             card = binascii.hexlify(card).decode().strip()