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Add mifare classic value block operations
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‎adafruit_pn532/adafruit_pn532.py

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"""
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import time
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import struct
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from digitalio import Direction
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from micropython import const
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@@ -501,6 +502,101 @@ def mifare_classic_write_block(
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)
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return response[0] == 0x0
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def mifare_classic_sub_value_block(self, block_number: int, amount: int) -> bool:
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"""Decrease the balance of a value block. Block number should be the block
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to change and amount should be an integer up to a maximum of 2147483647.
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If the value block is successfully updated then True is returned,
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otherwise False is returned.
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"""
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params = [0x01, MIFARE_CMD_DECREMENT, block_number & 0xFF]
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params.extend(list(amount.to_bytes(4, "little")))
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response = self.call_function(
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_COMMAND_INDATAEXCHANGE, params=params, response_length=1
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)
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if response[0] != 0x00:
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return False
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response = self.call_function(
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_COMMAND_INDATAEXCHANGE,
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params=[0x01, MIFARE_CMD_TRANSFER, block_number & 0xFF],
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response_length=1,
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)
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return response[0] == 0x00
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def mifare_classic_add_value_block(self, block_number: int, amount: int) -> bool:
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"""Increase the balance of a value block. Block number should be the block
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to change and amount should be an integer up to a maximum of 2147483647.
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If the value block is successfully updated then True is returned,
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otherwise False is returned.
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"""
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params = [0x01, MIFARE_CMD_INCREMENT, block_number & 0xFF]
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params.extend(list(amount.to_bytes(4, "little")))
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response = self.call_function(
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_COMMAND_INDATAEXCHANGE, params=params, response_length=1
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)
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if response[0] != 0x00:
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return False
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response = self.call_function(
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_COMMAND_INDATAEXCHANGE,
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params=[0x01, MIFARE_CMD_TRANSFER, block_number & 0xFF],
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response_length=1,
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)
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return response[0] == 0x00
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def mifare_classic_get_value_block(self, block_number: int) -> int:
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"""Read the contents of a value block and return a integer representing the
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current balance. Block number should be the block to read.
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"""
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block = self.mifare_classic_read_block(block_number=block_number)
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if block is None:
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return None
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value = block[0:4]
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value_inverted = block[4:8]
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value_backup = block[8:12]
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if value != value_backup:
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raise RuntimeError(
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"Value block bytes 0-3 do not match 8-11: "
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+ "".join("%02x" % b for b in block)
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)
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if value_inverted != bytearray(map((lambda x: x ^ 0xFF), value)):
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raise RuntimeError(
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"Inverted value block bytes 4-7 not valid: "
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+ "".join("%02x" % b for b in block)
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)
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return struct.unpack("<i", value)[0]
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def mifare_classic_fmt_value_block(
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self, block_number: int, initial_value: int, address_block: int = 0
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) -> bool:
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"""Formats a block on the card so it is suitable for use as a value block.
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Block number should be the block to use. Initial value should be an integer
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up to a maximum of 2147483647. Address block is optional and can be used
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as part of backup management.
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"""
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data = bytearray()
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initial_value = initial_value.to_bytes(4, "little")
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# Value
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data.extend(initial_value)
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# Inverted value
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data.extend(bytearray(map((lambda x: x ^ 0xFF), initial_value)))
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# Duplicate of value
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data.extend(initial_value)
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# Address
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address_block = address_block.to_bytes(1, "little")[0]
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data.extend(
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[address_block, address_block ^ 0xFF, address_block, address_block ^ 0xFF]
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)
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return self.mifare_classic_write_block(block_number, data)
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def ntag2xx_write_block(self, block_number: int, data: ReadableBuffer) -> bool:
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"""Write a block of data to the card. Block number should be the block
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to write and data should be a byte array of length 4 with the data to

‎examples/pn532_value_block_mifare.py

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# SPDX-FileCopyrightText: <text> 2015 Tony DiCola, Roberto Laricchia,
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# and Francesco Crisafulli, for Adafruit Industries </text>
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# SPDX-License-Identifier: MIT
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# Example of detecting and reading a value block from a MiFare classic NFC card.
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"""
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This example shows connecting to the PN532 and writing & reading a mifare classic
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type RFID tag
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"""
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import board
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import busio
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# Additional import needed for I2C/SPI
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# from digitalio import DigitalInOut
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#
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# NOTE: pick the import that matches the interface being used
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#
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from adafruit_pn532.adafruit_pn532 import MIFARE_CMD_AUTH_B
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from adafruit_pn532.i2c import PN532_I2C
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# from adafruit_pn532.spi import PN532_SPI
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# from adafruit_pn532.uart import PN532_UART
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# I2C connection:
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i2c = busio.I2C(board.SCL, board.SDA)
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# Non-hardware reset/request with I2C
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pn532 = PN532_I2C(i2c, debug=False)
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# With I2C, we recommend connecting RSTPD_N (reset) to a digital pin for manual
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# harware reset
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# reset_pin = DigitalInOut(board.D6)
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# On Raspberry Pi, you must also connect a pin to P32 "H_Request" for hardware
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# wakeup! this means we don't need to do the I2C clock-stretch thing
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# req_pin = DigitalInOut(board.D12)
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# pn532 = PN532_I2C(i2c, debug=False, reset=reset_pin, req=req_pin)
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# SPI connection:
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# spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
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# cs_pin = DigitalInOut(board.D5)
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# pn532 = PN532_SPI(spi, cs_pin, debug=False)
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# UART connection
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# uart = busio.UART(board.TX, board.RX, baudrate=115200, timeout=0.1)
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# pn532 = PN532_UART(uart, debug=False)
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ic, ver, rev, support = pn532.firmware_version
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print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
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# Configure PN532 to communicate with MiFare cards
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pn532.SAM_configuration()
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print("Waiting for RFID/NFC card to write to!")
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key_a = b"\xFF\xFF\xFF\xFF\xFF\xFF"
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key_b = b"\xFF\xFF\xFF\xFF\xFF\xFF"
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while True:
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# Check if a card is available to read
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uid = pn532.read_passive_target(timeout=0.5)
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print(".", end="")
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# Try again if no card is available.
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if uid is not None:
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break
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print("")
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print("Found card with UID:", [hex(i) for i in uid])
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print("Authenticating block 4 ...")
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authenticated = pn532.mifare_classic_authenticate_block(
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uid, 4, MIFARE_CMD_AUTH_B, key_b
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)
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if not authenticated:
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print("Authentication failed!")
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# Format block and set initial balance of 100
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response = pn532.mifare_classic_fmt_value_block(4, 100)
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print(
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response,
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"Formatted block 4, balance is:",
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pn532.mifare_classic_get_value_block(4),
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)
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response = pn532.mifare_classic_sub_value_block(4, 50)
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print(
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response,
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"Decrease by 50, new balance:",
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pn532.mifare_classic_get_value_block(4),
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)
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response = pn532.mifare_classic_add_value_block(4, 1337)
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print(
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response,
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"Increase by 1337, new balance:",
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pn532.mifare_classic_get_value_block(4),
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)

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