80 lines
2.4 KiB
Python
Executable File
80 lines
2.4 KiB
Python
Executable File
"""
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weigand.py - read card IDs from a wiegand card reader
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(C) 2017 Paul Jimenez - released under LGPLv3+
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"""
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from machine import Pin, Timer
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import utime
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CARD_MASK = 0b11111111111111110 # 16 ones
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FACILITY_MASK = 0b1111111100000000000000000 # 8 ones
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# Max pulse interval: 2ms
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# pulse width: 50us
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class Wiegand:
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def __init__(self, pin0, pin1, callback):
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"""
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pin0 - the GPIO that goes high when a zero is sent by the reader
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pin1 - the GPIO that goes high when a one is sent by the reader
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callback - the function called (with two args: card ID and cardcount)
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when a card is detected. Note that micropython interrupt
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implementation limitations apply to the callback!
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"""
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self.pin0 = Pin(pin0, Pin.IN)
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self.pin1 = Pin(pin1, Pin.IN)
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self.callback = callback
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self.last_card = None
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self.next_card = 0
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self._bits = 0
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self.pin0.irq(trigger=Pin.IRQ_FALLING, handler=self._on_pin0)
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self.pin1.irq(trigger=Pin.IRQ_FALLING, handler=self._on_pin1)
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self.last_bit_read = None
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self.timer = Timer(-1)
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self.timer.init(period=50, mode=Timer.PERIODIC, callback=self._cardcheck)
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self.cards_read = 0
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def _on_pin0(self, newstate):
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self._on_pin(0, newstate)
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def _on_pin1(self, newstate):
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self._on_pin(1, newstate)
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def _on_pin(self, is_one, newstate):
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now = utime.ticks_ms()
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if self.last_bit_read is not None and now - self.last_bit_read < 2:
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# too fast
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return
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self.last_bit_read = now
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self.next_card <<= 1
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if is_one:
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self.next_card |= 1
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self._bits += 1
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def get_card(self):
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if self.last_card is None:
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return None
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return (self.last_card & CARD_MASK) >> 1
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def get_facility_code(self):
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if self.last_card is None:
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return None
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# Specific to standard 26bit wiegand
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return (self.last_card & FACILITY_MASK) >> 17
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def _cardcheck(self, t):
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if self.last_bit_read is None:
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return
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now = utime.ticks_ms()
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if now - self.last_bit_read > 50:
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# too slow - new start!
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self.last_bit_read = None
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self.last_card = self.next_card
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self.next_card = 0
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self._bits = 0
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self.cards_read += 1
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self.callback(self.get_card(), self.get_facility_code(), self.cards_read)
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