88 lines
2.9 KiB
Python
88 lines
2.9 KiB
Python
# SPDX-FileCopyrightText: 2015-2018 Tony DiCola for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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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_bus_device import i2c_device
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from digitalio import Direction
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from micropython import const
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from adafruit_pn532.adafruit_pn532 import PN532, BusyError
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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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resetp pin and debugging output.
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"""
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self.debug = debug
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self._req = req
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self._i2c = i2c_device.I2CDevice(i2c, _I2C_ADDRESS)
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super().__init__(debug=debug, irq=irq, 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._reset_pin:
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self._reset_pin.value = True
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time.sleep(0.01)
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if self._req:
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self._req.direction = Direction.OUTPUT
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self._req.value = False
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time.sleep(0.01)
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self._req.value = True
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time.sleep(0.01)
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self.low_power = False
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self.SAM_configuration() # Put the PN532 back in normal mode
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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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continue
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if status == b"\x01":
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return True # No longer busy
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time.sleep(0.01) # 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 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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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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