rfid_utils – the main helper module

This module provides pre-configured instances of the board LEDs, input and output pins, and the buzzer. It also provides a simplified wrapper for the mfrc522 class.

Pre-defined objects

  • RGB - an instance of the SmartLED class.

  • GLED, RLED - instances of the SignalLED class.

    The name GLED (shorthand for the Green LED) is kept for compatibility reasons. The default color of this led is 0x1FFFFF. The name RLED (shorthand for the Red LED) is kept for compatibility reasons. The default color of this led is 0xFF1FFF.

  • OUT - an instance of the pin, controlling the OUT+ - OUT- pair on the board. OUT(1) pulls the OUT- to the ground, OUT(0) leaves it floating. The OUT+ is always connected to the positive power input.

  • IN - an instance of the pin, corresponding to the IN contact on the board. IN.value() returns 1 when the IN contact is floating, 0 when the IN contact is short-circuited to the ground.

  • BUZZ - an instance of the Buzzer.

Classes

class rfid_utils.CardFilter(lifetime)

lifetime is the life time of an entry in seconds.

The class inherits a dictionary, but it’s intended use is more like a set:

c_filter = CardFilter(2)
while 1:
        c_filter.clean(time())
        uid = rfid.read()
        if uid not in c_filter:
                # Process the new uid
                c_filter.append(uid)
append(value)

Puts the value and the current time in the dict. This can also be used to refresh the value (for example, update the “last seen” time).

clean(now=None)

Remove all entries with expired lifetime.

class rfid_utils.RFID(gain=rfid.G_33dB, key=None, type=None, ul=None)

  • gain - the RFID receiver gain

  • key - Mifare Classic tag access key (None or a byte-like object)

  • typ - the key type (b'A', or b'B', or rfid.KEY_A, or rfid.KEY_B). If provided, the key should be 6 bytes long. If None, and the key is not None, the key should be 6 bytes long (will be interpreted as the Mifare Classic A key).

  • ul - the Mifare Ultralight password (and integer or a 4 byes long byte-like object).

read(fmt='hU*', key=None, type=None, ul=None)

  • fmt - the format of the output (ref. (RFID format string)[https://open-dev.ru/rfid-format])

  • key, typ, ul - if not None, override the corresponding constructor parameter.

scan():

Resets the rfid IC and scans for a tag. Refer to the scan() method of the mfrc522 class.

write(block, data, key=None, typ=None, ul=None)

  • block - the number of the block to be written. Starts at zero (NB: most tags have a read-only first block).

  • data - a bytes-like object. Must be 4 or 16 bytes long, depending on the type of the tag.

  • key, typ, ul - if not None, override the corresponding constructor parameter.

  • the typ parameter accepts only the rfid.KEY_A or rfid.KEY_B constants.