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Initial setup of MFRC522 for Pico.

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Lars Hahn 2024-10-22 19:24:50 +02:00
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import logging
from machine import Pin, SPI
class UMFRC522:
"""Class for connecting and controlling to a MFRC522 RFID reader.
Can be used to interact with RFID token; writing data and even updating
authentication keys of whole sectors.
Theoretical documentation can be found at the BASEDOCU here:
https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf
This code basis on the implementation of 1AdityaX at
https://github.com/1AdityaX/mfrc522-python
"""
# default clean register states refer to BASEDOCU page 36ff.
CLEAN_REGISTER_STATES = {
0x2A: 0b10001101, # TModeReg
0x2B: 0b00111110, # TPrescalerReg, lower 8 bits
0x2D: 0b00011110, # TReloadReg, lower 8 bits
0x2C: 0b00000000, # TReloadReg, higher 8 bits
0x15: 0b01000000, # TxASKReg
0x11: 0b00111101 # ModeReg
}
# Mask for adressing data bits when acting with registers,
# leftest and rightest bits are special handled
MASK_SPI_DATA = 0b01111110
# Mask e.g. to add leading bit
MASK_LEADING_BIT = 0b10000000
# Consider err (l2r): Protocol, Parity, x , collision,
# buffer overflow, x , x, x
MASK_ERROR = 0b00011011
STATUS_ERROR = 0x02
STATUS_NO_TOKEN = 0x01
STATUS_OK = 0x00
REG_TX_CONTROL = 0x14
REG_COMMAND = 0x01
REG_COM_I_EN = 0x02
REG_COM_IRQ = 0x04
REG_FIFO_LEVEL = 0x0A
REG_FIFO_DATA = 0x09
REG_BIT_FRAMING = 0x0D
REG_ERROR = 0x06
REG_CONTROL = 0x0C
REG_DIV_IRQ = 0x05
REG_CRC_RESULT_LEFT = 0x22
REG_CRC_RESULT_MID = 0x21
REG_STATUS = 0x08
COMMAND_CLEAN = 0b1111
COMMAND_IDLE = 0b0000
COMMAND_AUTHENTICATE = 0b1110
COMMAND_TRANSCEIV = 0b1100
COMMAND_CALC_CRC = 0b0011
COMMAND_SELECT_TOKEN = 0x93
COMMAND_ANTICOLLISION = COMMAND_SELECT_TOKEN
COMMAND_READ = 0x30
COMMAND_WRITE = 0xA0
REQUEST_IDLE = 0x26
REQUEST_ALL = 0x52
LEN_MAX = 16 # maximum 16 bytes per block in a sector
AUTH_MODE_A = 0x60
AUTH_MODE_B = 0x61
def id_to_string(serial_number):
"""Converts 5-byte serial-number digit list into
human readable string.
Keyword arguments:
serial_number -- list of 5 digits, digit < 256
"""
return int.from_bytes(bytes(serial_number[:-1]), "little", False)
def __init__(
self, sck, mosi, miso, rst, cs,
baudrate=1000000, spi_dev=0, debug_level=logging.WARNING):
"""Constructor to initialise the RC522 card reader for Raspberry Pico.
Keyword arguments:
sck -- Serial Clock pin
mosi -- MasterOutSlaveIn pin
miso -- MasterInSlaveOut pin
rst -- Reset pin
cs -- Chip select pin
baudrate -- Transmission rate (default 1000000)
spi_dev -- SerialPortInterface device (default 0)
debug_level -- Logger level for debuggin (default loggin.WARNING)
"""
self._logger = logging.getLogger("Umfrc522Logger")
self._logger.setLevel(debug_level)
self._baudrate = baudrate
self._sck = Pin(sck, Pin.OUT) # serial clock
self._mosi = Pin(mosi, Pin.OUT) # master out, slave in
self._miso = Pin(miso) # master in, slave out
self._rst = Pin(rst, Pin.OUT, value=0)
self._cs = Pin(cs, Pin.OUT, value=1) # chip select
self._spi = SPI(
spi_dev, baudrate=self._baudrate, polarity=0, phase=0,
sck=self._sck, mosi=self._mosi, miso=self._miso
)
self._rst.on()
self.clear_state()
def _register_write(self, addr, data):
"""Internal write function, directly writes a byte to a given address.
Keyword arguments:
addr -- The register where data should be written into.
data -- The data to be written, a single byte.
"""
# Follows BASEDOCU logic on Chapter 8.1.2.3
# leftest bit (#7) of data byte defines action, '1' is read, '0' write
# rightest bit (#0) is always 0.
self._cs.off()
addr_byte = bytes([(addr << 1) & self.MASK_SPI_DATA])
data_byte = bytes([data & 0b11111111])
self._spi.write(addr_byte)
self._spi.write(data_byte)
self._cs.on()
def _register_read(self, addr):
"""Internal read function, directly reads a byte from a given address.
Keyword arguments:
addr -- The register where data should be read from.
Returns:
single byte of given address.
"""
# Follows BASEDOCU logic on Chapter 8.1.2.3
# leftest bit (#7) of data byte defines action, '1' is read, '0' write
# rightest bit (#0) is always 0.
self._cs.off()
# shift bits to left by 1 position for trailing 0 and ensure length
# with mask + attach leading '1' for reading access.
addr_byte = bytes(
[(addr << 1) & self.MASK_SPI_DATA | self.MASK_LEADING_BIT]
)
self._spi.write(addr_byte)
data = self._spi.read(1)
self._cs.on()
return data[0]
def _bitmask_set(self, reg, mask):
"""Internal mask function to apply a bitmask to a certain
register of the RC522 reader.
Keyword arguments:
reg -- Register, to which the mask should be applied.
mask -- The bit mask (8 bits max) to be applied.
"""
masked_byte = self._register_read(reg) | mask
self._register_write(reg, masked_byte)
def _bitmask_clear(self, reg, mask):
"""Internal mask function to un-apply a bitmask to a certain
register of the RC522 reader.
Keyword arguments:
reg -- Register, to which the mask should be un-applied from.
mask -- The bit mask (8 bits max) to be un-applied.
"""
unmasked_byte = self._register_read(reg) & (~mask)
self._register_write(reg, unmasked_byte)
def _antenna_on(self):
"""Internal function to enable the antenna of the RC522 reader module.
"""
mask = 0b00000011
data = self._register_read(self.REG_TX_CONTROL)
if (data & mask) != mask:
self._bitmask_set(self.REG_TX_CONTROL, mask=mask)
def _antenna_off(self):
"""Internal function to disable the antenna of the RC522 reader module.
"""
self._bitmask_clear(self.REG_TX_CONTROL, 0b00000011)
def _to_card(self, command, data):
"""Internal function to send commands to the reader and the connected
RFID card/token.
Keyword arguments:
command -- Byte, command to be executed, depends on a
previously activated register.
data -- Byte, that should be send to the card with the command.
Returns:
status, data, bits -- Response from the card with a status, some data
and some response bits.
"""
recv_data = []
recv_data_leng = 0
recv_bytes = 0
status = self.STATUS_ERROR
interrupt_request = 0x0
wait_interrupt_request = 0x0
last_bits = None
if command == self.COMMAND_AUTHENTICATE:
interrupt_request = 0b00010010
wait_interrupt_request = 0b00010000
elif command == self.COMMAND_TRANSCEIV:
interrupt_request = 0b01110111
wait_interrupt_request = 0b00110000
# Interrupt enabling and reset FIFO buffer of data
self._register_write(
self.REG_COM_I_EN,
interrupt_request | self.MASK_LEADING_BIT
)
self._bitmask_clear(self.REG_COM_IRQ, self.MASK_LEADING_BIT)
self._bitmask_set(self.REG_FIFO_LEVEL, self.MASK_LEADING_BIT)
# Set into IDLE mode
self._register_write(self.REG_COMMAND, self.COMMAND_IDLE)
# Put data into FIFO buffer
for byte in data:
self._register_write(self.REG_FIFO_DATA, byte)
# Execute Command on data
self._register_write(self.REG_COMMAND, command)
if command == self.COMMAND_TRANSCEIV:
self._bitmask_set(self.REG_BIT_FRAMING, self.MASK_LEADING_BIT)
wait_ctr = 2000
command_executed = False
while not command_executed:
recv_bytes = self._register_read(self.REG_COM_IRQ)
wait_ctr -= 1
if not wait_ctr:
self._logger.error("Could not execute command. Timeout.")
break
if (recv_bytes & 0x01) or (recv_bytes & wait_interrupt_request):
command_executed = True
if command == self.COMMAND_TRANSCEIV:
self._bitmask_clear(self.REG_BIT_FRAMING, self.MASK_LEADING_BIT)
# Status check and adjustments
errors = self._register_read(self.REG_ERROR)
if errors & self.MASK_ERROR:
# at least one bit considered is set to true -> we got an error;
# TODO: parse errors in future
status = self.STATUS_ERROR
else:
status = self.STATUS_OK
if recv_bytes & interrupt_request & 0x01:
status = self.STATUS_NO_TOKEN
if command == self.COMMAND_TRANSCEIV:
recv_bytes = self._register_read(self.REG_FIFO_LEVEL)
last_bits = self._register_read(self.REG_CONTROL) & 0b00000111
recv_data_leng = (
(recv_bytes - 1) * 8 + last_bits
if last_bits
else
recv_bytes * 8
)
recv_bytes = min(max(recv_bytes, 1), self.LEN_MAX)
recv_data = [
self._register_read(self.REG_FIFO_DATA)
for _ in range(recv_bytes)
]
return (status, recv_data, recv_data_leng)
def _get_crc(self, data):
"""Internal function to calculate the CRC / checksum given
some input data that will be written to the reader.
Keyword arguments:
data -- The data (list of bytes) to be used for CRC calculation.
Returns:
bit-list -- List of the CRC bits, left and then right bits.
"""
# Clearing Interrupts and settion FIFO to maximum
# third bit was for collision detection in BASEDOCU table 34.
self._bitmask_clear(self.REG_DIV_IRQ, 0b00000100)
self._bitmask_set(self.REG_FIFO_LEVEL, self.MASK_LEADING_BIT)
for datum in data:
self._register_write(self.REG_FIFO_DATA, datum)
self._register_write(self.REG_COMMAND, self.COMMAND_CALC_CRC)
wait_ctr = 255
crc_completed = False
while not crc_completed:
recv_bytes = self._register_read(self.REG_DIV_IRQ)
wait_ctr -= 1
if not wait_ctr:
self._logger.error("Could not calculate CRC. Timeout.")
break
if recv_bytes & 0b0100:
# Bit #2 (3. pos) shows data is processed, BASEDOCU Table 32.
crc_completed = True
return [
self._register_read(self.REG_CRC_RESULT_LEFT),
self._register_read(self.REG_CRC_RESULT_MID)
]
def _anti_collision(self):
"""Internal function to perform an anti-collision algorithm
on the reader and return one dedicated serial number of a close
RFID token
Returns:
status, serial_number -- The status of algorithm success and if positiv
the serial number bits of a close token/card.
"""
serial_number_check = 0
serial_numbers = [self.COMMAND_ANTICOLLISION, 0x20]
self._register_write(self.REG_BIT_FRAMING, 0x00)
status, recv_data, _ = self._to_card(
self.COMMAND_TRANSCEIV, serial_numbers
)
if status == self.STATUS_OK and len(recv_data) == 5:
for i in range(4):
# calculating Checksum; should match 5ths byte
serial_number_check = serial_number_check ^ recv_data[i]
if serial_number_check != recv_data[4]:
status = self.STATUS_ERROR
else:
status = self.STATUS_ERROR
return status, recv_data
def _select_token(self, serial_number):
"""Internal function to select and estabilish the connection/
communication to a token close to the RFID reader.
Keyword arguments:
serial_number -- list of bytes corresponding to the serial ID / UID
of a nearby RFID token/card.
Returns:
byte -- first byte of the command response or 0 in fail.
"""
data = [self.COMMAND_SELECT_TOKEN, 0x70]
data.extend(serial_number)
data.extend(self._get_crc(data))
status, recv_data, recv_data_leng = self._to_card(
self.COMMAND_TRANSCEIV, data
)
if status == self.STATUS_OK and (recv_data_leng == 24):
return recv_data[0]
else:
return 0
def _write_block(self, block_id, data):
"""Internal function to write to a dedicated block on the card.
Requires authentication and selection of a card beforehand.
There is NO limitation on blocks; sector 0 and trailing blocks in
each sector can be written.
Keyword arguments:
block_id -- the global ID of a block to be written (0-63).
data -- the list of 16 bytes to be written into the block.
"""
data_buffer = [self.COMMAND_WRITE, block_id]
data_buffer.extend(self._get_crc(data_buffer))
status, recv_data, recv_data_leng = self._to_card(
self.COMMAND_TRANSCEIV, data_buffer
)
if (
status != self.STATUS_OK or
recv_data_leng != 4 or
(recv_data[0] & 0x0F) != 0x0A
):
self._logger.error(
f"Could not init write-data to block {block_id}. Abort."
)
return
data_buffer = list(data)
data_buffer.extend(self._get_crc(data_buffer))
status, recv_data, recv_data_leng = self._to_card(
self.COMMAND_TRANSCEIV, data_buffer
)
if (
status != self.STATUS_OK or
recv_data_leng != 4 or
(recv_data[0] & 0x0F) != 0x0A
):
self._logger.error(
f"Could not write data to block {block_id}. Abort."
)
def _read_block(self, block_id):
"""Internal function to read of a dedicated block on the card.
Requires authentication and selection of a card beforehand.
There is no limitation on blocks; sector 0 and trailing blocks in
each sector can be read.
Keyword arguments:
block_id -- the global ID of a block to be written (0-63).
Returns:
byte-list -- list of 16 bytes read from the given block.
"""
data = [self.COMMAND_READ, block_id]
data.extend(self._get_crc(data))
status, recv_data, _ = self._to_card(self.COMMAND_TRANSCEIV, data)
if status != self.STATUS_OK:
self._logger.error(
f"Could not read data from block {block_id}. Abort."
)
return None
if len(recv_data) != self.LEN_MAX:
self._logger.error(
f"Incomplete data ({len(recv_data)} / {self.LEN_MAX} bytes) "
f"from block {block_id}. Abort."
)
return None
return recv_data
def reset(self):
"""Function to reset the MFRC522 RFID reader."""
self._register_write(self.REG_COMMAND, self.COMMAND_CLEAN)
def clear_state(self):
"""Function to initialise the MFRC522 RFID reader into
a clear state; ready to authenticate with close card/token.
"""
self.reset()
for addr, data in self.CLEAN_REGISTER_STATES.items():
self._register_write(addr, data)
self._antenna_on()
def request(self, mode):
"""Funtion to send a request command for interacting with a near by
RFID card/token.
Keyword arguments:
mode -- The authentication mode, either UMFRC522.AUTH_MODE_A or .._B.
Returns:
status, bit number -- The status and the bits received from the token.
"""
self._register_write(self.REG_BIT_FRAMING, 0b0111)
status, _, recv_data_leng = self._to_card(
self.COMMAND_TRANSCEIV, [mode]
)
if (status != self.STATUS_OK) or (recv_data_leng != self.LEN_MAX):
status = self.STATUS_ERROR
return status, recv_data_leng
def select_near_token(self):
"""Function to select and connect to the nearest RFID token.
Performs internally the anticollision algorithm and establishes
a connection to the card/token.
Returns:
status, serial_number -- Status of the connection and the list of
bytes representing the serial number of the connected token/card.
"""
status, serial_number = self._anti_collision()
if status != self.STATUS_OK:
return status, []
select_status = self._select_token(serial_number)
if select_status == 0:
return self.STATUS_ERROR, []
return status, serial_number
def authenticate(self, serial_number, block, sector_key, auth_mode):
"""Function to authenticate to a given login block and work with data.
The block has always to be a trailing block of a sector, e.g.
for sector 3, trailing block is 3*4 +3 => block with ID 15.
Keyword arguments:
serial_number -- List of bytes corresponding to the serial ID / UID
of a nearby RFID token/card.
block -- The global id (0-63) of a block to log into the corresponding
sector, e.g. for Sector 3, login block ID is 3*4 +3 = 15.
sector_key -- The authentication key for the block to log in.
auth_mode -- The auth mode, either UMFRC522.AUTH_MODE_A or .._B.
Decides on the password bits. _A may not be the same as _B.
Returns:
status -- Status of success of authenticating to a sector/block.
"""
if block % 4 != 3:
recommendation = (block // 4) + 3
self._logger.error(
"Authentication can only be done to a "
"trailing block of a sector. "
f"Login block for '{block}' "
f"is block with ID '{recommendation}'. "
"Abort."
)
data = [auth_mode, block]
data.extend(sector_key)
data.extend(serial_number[:-1])
status, _, _ = self._to_card(self.COMMAND_AUTHENTICATE, data)
if status != self.STATUS_OK:
self._logger.error(
"Cannot authenticate to token with ID "
f"'{UMFRC522.id_to_string(serial_number)}'"
)
return status
def authenticate_cancel(self):
"""Function to stop authentication on the card.
Is always needed before when switching to a differen card.
"""
self._bitmask_clear(self.REG_STATUS, self.REG_STATUS)
def read(self, block_id):
"""Function to read data of a block_id from the RFID token/card.
Requires authentication and selection of a token in beforehand.
Keyword arguments:
block_id -- the global ID of a block to be read from (0-63).
Returns:
bytes -- list of 16 bytes, data from the given block_id on the card.
"""
return self._read_block(block_id)
def write(self, block_id, data):
"""Function to write data to a block_id on the RFID token/card.
Writes in safe-mode, trailing blocks of sectors or the first sector
cannot be written to.
Requires authentication and selection of a token in beforehand.
block_id -- the global ID of a block to be written to (0-63).
data -- the list of 16 bytes to be written into the block.
"""
sector = block_id // 4
sector_block = block_id % 4
if sector == 0:
# first block contains munfacturer info, do not overwrite!
self._logger.error(
"Unsafe write into manufacturer sector '0'. Abort."
)
return
if sector_block == 3:
self._logger.error(
# trailing block in each sector contains password information,
# do not overwrite!
"Unsafe write into trailing credential block "
f"'{block_id}' of sector '{sector}'. Abort."
)
return
return self._write_block(block_id, data)
def update_sector_auth_key(self, sector, new_sector_key, auth_mode):
"""Function to update the authentication key with a given auth mode
on a certain sector (0-15). Do NOT mixup sector with blocks, there are
16 sectors on the card, each sector having 4 blocks; thus in total 64
blocks on the card. We make use here of the SECTORS!
Requires authentication and selection of a token in beforehand.
Keyword arguments:
sector -- The sector id (0-15) where the key change should take action.
new_sector_key -- list of 6 bytes, containing the new auth key.
auth_mode -- The auth mode, either UMFRC522.AUTH_MODE_A or .._B.
Decides on the password bits. _A may not be the same as _B.
"""
if auth_mode not in (self.AUTH_MODE_A, self.AUTH_MODE_B):
self._logger.error(
"Update key requires valid auto mode, either "
"UMFRC522.AUTH_MODE_A or UMFRC522.AUTH_MODE_B. Abort."
)
return self.STATUS_ERROR
if (
len(new_sector_key) != 6 or
any(not isinstance(c, int) or c > 255 for c in new_sector_key)
):
self._logger.error(
"New sector key needs to be list of exact 6 bytes. Abort."
)
return self.STATUS_ERROR
credential_block = sector*4 + 3
self._logger.info(
f"Update credential effects block with ID '{credential_block}'"
)
data = self._read_block(credential_block)
if auth_mode == self.AUTH_MODE_A:
new_data = new_sector_key + data[6:]
else:
new_data = data[:-6] + new_sector_key
self._write_block(credential_block, new_data)
if __name__ == "__main__":
import utime
try:
reader = UMFRC522(spi_dev=0, sck=6, miso=4, mosi=7, cs=5, rst=22)
while True:
reader.clear_state()
status, token = reader.request(reader.REQUEST_IDLE)
if status == reader.STATUS_OK:
status, serial_number = reader.select_near_token()
if status == reader.STATUS_OK:
card_id = UMFRC522.id_to_string(serial_number)
print(f"CARD ID: {card_id}\n")
default_key = [0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]
for sector in range(16):
if sector == 0:
print(
f"__Sector__ ____{'____ ____'.join(
'block__'+str(i) for i in range(4)
)}____"
)
login_block = sector*4 + 3
status = reader.authenticate(
serial_number, login_block,
default_key, reader.AUTH_MODE_A
)
if status != reader.STATUS_OK:
continue
try:
sector_text = " ".join(
"".join(
chr(c) if c > 32 and c < 127 else '.'
for c in reader.read(
sector*4 + sector_block
)
)
for sector_block in range(4)
)
print(f"Sector {sector: 02d}: {sector_text}")
except TypeError:
break # When removing card, just skip
else:
print(f"No Card\r", end="")
utime.sleep_ms(500)
except KeyboardInterrupt:
print(f"\r{" "*80}\r") # Clean the latest line