1  # Adafruit PN532 NFC/RFID control library.
  2  # Author: Tony DiCola
  3  #
  4  # The MIT License (MIT)
  5  #
  6  # Copyright (c) 2015-2018 Adafruit Industries
  7  #
  8  # Permission is hereby granted, free of charge, to any person obtaining a copy
  9  # of this software and associated documentation files (the "Software"), to deal
 10  # in the Software without restriction, including without limitation the rights
 11  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 12  # copies of the Software, and to permit persons to whom the Software is
 13  # furnished to do so, subject to the following conditions:
 14  #
 15  # The above copyright notice and this permission notice shall be included in
 16  # all copies or substantial portions of the Software.
 17  #
 18  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 19  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 20  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 21  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 22  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 23  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 24  # THE SOFTWARE.
 25  """
 26  ``adafruit_pn532.i2c``
 27  ====================================================
 28  
 29  This module will let you communicate with a PN532 RFID/NFC shield or breakout
 30  using I2C.
 31  
 32  * Author(s): Original Raspberry Pi code by Tony DiCola, CircuitPython by ladyada,
 33               refactor by Carter Nelson
 34  
 35  """
 36  
 37  __version__ = "0.0.0-auto.0"
 38  __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_PN532.git"
 39  
 40  import time
 41  import adafruit_bus_device.i2c_device as i2c_device
 42  from digitalio import Direction
 43  from micropython import const
 44  from adafruit_pn532.adafruit_pn532 import PN532, BusyError, _reset
 45  
 46  # pylint: disable=bad-whitespace
 47  _I2C_ADDRESS = const(0x24)
 48  
 49  
 50  class PN532_I2C(PN532):
 51      """Driver for the PN532 connected over I2C."""
 52  
 53      def __init__(self, i2c, *, irq=None, reset=None, req=None, debug=False):
 54          """Create an instance of the PN532 class using I2C. Note that PN532
 55          uses clock stretching. Optional IRQ pin (not used),
 56          reset pin and debugging output.
 57          """
 58          self.debug = debug
 59          self._irq = irq
 60          self._req = req
 61          if reset:
 62              _reset(reset)
 63          self._i2c = i2c_device.I2CDevice(i2c, _I2C_ADDRESS)
 64          super().__init__(debug=debug, reset=reset)
 65  
 66      def _wakeup(self):  # pylint: disable=no-self-use
 67          """Send any special commands/data to wake up PN532"""
 68          if self._req:
 69              self._req.direction = Direction.OUTPUT
 70              self._req.value = True
 71              time.sleep(0.1)
 72              self._req.value = False
 73              time.sleep(0.1)
 74              self._req.value = True
 75          time.sleep(0.5)
 76  
 77      def _wait_ready(self, timeout=1):
 78          """Poll PN532 if status byte is ready, up to `timeout` seconds"""
 79          status = bytearray(1)
 80          timestamp = time.monotonic()
 81          while (time.monotonic() - timestamp) < timeout:
 82              try:
 83                  with self._i2c:
 84                      self._i2c.readinto(status)
 85              except OSError:
 86                  self._wakeup()
 87                  continue
 88              if status == b"\x01":
 89                  return True  # No longer busy
 90              time.sleep(0.05)  # lets ask again soon!
 91          # Timed out!
 92          return False
 93  
 94      def _read_data(self, count):
 95          """Read a specified count of bytes from the PN532."""
 96          # Build a read request frame.
 97          frame = bytearray(count + 1)
 98          with self._i2c as i2c:
 99              i2c.readinto(frame, end=1)  # read status byte!
100              if frame[0] != 0x01:  # not ready
101                  raise BusyError
102              i2c.readinto(frame)  # ok get the data, plus statusbyte
103          if self.debug:
104              print("Reading: ", [hex(i) for i in frame[1:]])
105          else:
106              time.sleep(0.1)
107          return frame[1:]  # don't return the status byte
108  
109      def _write_data(self, framebytes):
110          """Write a specified count of bytes to the PN532"""
111          with self._i2c as i2c:
112              i2c.write(framebytes)