120 lines
4.7 KiB
Python
120 lines
4.7 KiB
Python
# 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.spi``
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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 SPI.
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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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import adafruit_bus_device.spi_device as spi_device
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from micropython import const
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from adafruit_pn532.adafruit_pn532 import PN532
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# pylint: disable=bad-whitespace
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_SPI_STATREAD = const(0x02)
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_SPI_DATAWRITE = const(0x01)
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_SPI_DATAREAD = const(0x03)
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_SPI_READY = const(0x01)
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def reverse_bit(num):
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"""Turn an LSB byte to an MSB byte, and vice versa. Used for SPI as
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it is LSB for the PN532, but 99% of SPI implementations are MSB only!"""
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result = 0
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for _ in range(8):
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result <<= 1
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result += (num & 1)
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num >>= 1
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return result
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class PN532_SPI(PN532):
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"""Driver for the PN532 connected over SPI. Pass in a hardware or bitbang
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SPI device & chip select digitalInOut pin. Optional IRQ pin (not used),
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reset pin and debugging output."""
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def __init__(self, spi, cs_pin, *, irq=None, reset=None, debug=False):
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"""Create an instance of the PN532 class using SPI"""
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self.debug = debug
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self._irq = irq
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self._spi = spi_device.SPIDevice(spi, cs_pin)
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super().__init__(debug=debug, reset=reset)
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def _wakeup(self):
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"""Send any special commands/data to wake up PN532"""
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with self._spi as spi:
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time.sleep(1)
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spi.write(bytearray([0x00])) #pylint: disable=no-member
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time.sleep(1)
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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([reverse_bit(_SPI_STATREAD), 0])
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timestamp = time.monotonic()
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while (time.monotonic() - timestamp) < timeout:
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with self._spi as spi:
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time.sleep(0.02) # required
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spi.write_readinto(status, status) #pylint: disable=no-member
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if reverse_bit(status[1]) == 0x01: # LSB data is read in MSB
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return True # Not busy anymore!
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else:
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time.sleep(0.01) # pause a bit till we ask again
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# We 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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# Add the SPI data read signal byte, but LSB'ify it
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frame[0] = reverse_bit(_SPI_DATAREAD)
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with self._spi as spi:
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time.sleep(0.02) # required
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spi.write_readinto(frame, frame) #pylint: disable=no-member
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for i, val in enumerate(frame):
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frame[i] = reverse_bit(val) # turn LSB data to MSB
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if self.debug:
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print("Reading: ", [hex(i) for i in frame[1:]])
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return frame[1:]
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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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# start by making a frame with data write in front,
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# then rest of bytes, and LSBify it
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rev_frame = [reverse_bit(x) for x in bytes([_SPI_DATAWRITE]) + framebytes]
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if self.debug:
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print("Writing: ", [hex(i) for i in rev_frame])
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with self._spi as spi:
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time.sleep(0.02) # required
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spi.write(bytes(rev_frame)) #pylint: disable=no-member
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