Made _tocard delay configurable. Allows to reduce delay.

mfrc522.py

@@ -24,8 +24,7 @@ class MFRC522:
     PICC_ANTICOLL2 = 0x95
     PICC_ANTICOLL3 = 0x97
 
-
-    def __init__(self, sck, mosi, miso, rst, cs,baudrate=1000000,spi_id=0):
+    def __init__(self, sck, mosi, miso, rst, cs, baudrate=1000000, spi_id=0, tocard_retries=2000):
 
         self.sck = Pin(sck, Pin.OUT)
         self.mosi = Pin(mosi, Pin.OUT)
@@ -39,6 +38,8 @@ class MFRC522:
         self.NTAG_MaxPage = 0
         board = uname()[0]
 
+        self.tocard_retries=tocard_retries
+
         if board == 'WiPy' or board == 'LoPy' or board == 'FiPy':
             self.spi = SPI(0)
             self.spi.init(SPI.MASTER, baudrate=1000000, pins=(self.sck, self.mosi, self.miso))
@@ -100,7 +101,7 @@ class MFRC522:
         if cmd == 0x0C:
             self._sflags(0x0D, 0x80)
 
-        i = 2000
+        i = self.tocard_retries
         while True:
             n = self._rreg(0x04)
             i -= 1