110 lines
4 KiB
Python
110 lines
4 KiB
Python
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# Adafruit PN532 NFC/RFID control library.
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# Author: Tony DiCola
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#
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# The MIT License (MIT)
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#
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# Copyright (c) 2015-2018 Adafruit Industries
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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"""
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``adafruit_pn532.i2c``
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====================================================
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This module will let you communicate with a PN532 RFID/NFC shield or breakout
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using I2C.
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* Author(s): Original Raspberry Pi code by Tony DiCola, CircuitPython by ladyada,
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refactor by Carter Nelson
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"""
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__version__ = "0.0.0-auto.0"
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__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_PN532.git"
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import time
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from adafruit_pn532.adafruit_pn532 import PN532
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import adafruit_bus_device.i2c_device as i2c_device
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from micropython import const
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_I2C_ADDRESS = const(0x24)
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class PN532_I2C(PN532):
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"""Driver for the PN532 connected over I2C."""
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def __init__(self, i2c, *, irq=None, reset=None, req=None, debug=False):
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"""Create an instance of the PN532 class using I2C. Note that PN532
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uses clock stretching. Optional IRQ pin (not used),
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reset pin and debugging output.
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"""
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self.debug = debug
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self._irq = irq
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self._req = req
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if reset:
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_reset(reset)
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self._i2c = i2c_device.I2CDevice(i2c, _I2C_ADDRESS)
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super().__init__(debug=debug, reset=reset)
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def _wakeup(self): # pylint: disable=no-self-use
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"""Send any special commands/data to wake up PN532"""
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if self._req:
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self._req.direction = Direction.OUTPUT
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self._req.value = True
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time.sleep(0.1)
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self._req.value = False
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time.sleep(0.1)
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self._req.value = True
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time.sleep(0.5)
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def _wait_ready(self, timeout=1):
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"""Poll PN532 if status byte is ready, up to `timeout` seconds"""
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status = bytearray(1)
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timestamp = time.monotonic()
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while (time.monotonic() - timestamp) < timeout:
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try:
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with self._i2c:
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self._i2c.readinto(status)
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except OSError:
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self._wakeup()
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continue
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if status == b'\x01':
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return True # No longer busy
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else:
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time.sleep(0.05) # lets ask again soon!
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# Timed out!
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return False
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def _read_data(self, count):
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"""Read a specified count of bytes from the PN532."""
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# Build a read request frame.
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frame = bytearray(count+1)
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with self._i2c as i2c:
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i2c.readinto(frame, end=1) # read status byte!
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if frame[0] != 0x01: # not ready
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raise pn532.BusyError
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i2c.readinto(frame) # ok get the data, plus statusbyte
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if self.debug:
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print("Reading: ", [hex(i) for i in frame[1:]])
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else:
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time.sleep(0.1)
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return frame[1:] # don't return the status byte
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def _write_data(self, framebytes):
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"""Write a specified count of bytes to the PN532"""
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with self._i2c as i2c:
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i2c.write(framebytes)
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