Simple Python class to interpret a raw bit stream as read from an EM410x RFID tag.

em410x.py

#!/usr/bin/env python3


class EM410x:
    def __init__(self, bits):
        assert len(bits) == 64
        self.header = bits[:9]
        self.nibbles = []
        for i in range(9, 9 + 5 * 11, 5):
            self.nibbles.append((bits[i:i+4], bits[i+4]))


    def __str__(self):
        site = ''.join(n[0] for n in self.nibbles[:2])
        id = ''.join(n[0] for n in self.nibbles[2:-1])
        unique_id = ''.join(n[0][::-1] for n in self.nibbles[0:-1])
        return (
            '<EM4100 header={hdr!r}'
            ' data={data!r}'
            ' (site={site:02x} id={id:08x} parity={par!r}, uniq={uniq:10x})>'.format(
                hdr='0b' + self.header,
                data=self.nibbles,
                site=int(site, 2),
                id=int(id, 2),
                par=self.nibbles[-1],
                uniq=int(unique_id, 2)
            )
        )



if __name__ == '__main__':
    import sys
    print(EM410x(sys.argv[1]))