string_to_bcd

# https://en.wikipedia.org/wiki/Binary-coded_decimal
def string_to_bcd(string):
    n = [int(c) for c in string]
    bcd = [format(d, '04b') for d in n]
    return bcd

bcd = string_to_bcd("402")
print(bcd) # ['0100', '0000', '0010']





# UPDATED and expanded solution, allows to use also 16, 8 and 2 base and negative numbers
# Also if wanted BCD as packed, possible...
def to_bcd(s, packed=True):
    '''
    Converts 2, 8, 10 and 16 based numbers to
    BCD code with sign at the end
    supports values of
     - packaged and unpacked
     - positive and negative
    not supported
     - float numbers
    '''
    BASES = { "b": 2, "o": 8, "x": 16 }
    def get_base(s):
        ''' Get number system from the string '''
        s.lower()
        try: return BASES[s[1]]
        except: return 10

    # If given value is negative, change it positive
    try:
        negative = True if s[0] == "-" else False
        s = s[1:] if negative else s
    except:
        negative = True if s < 0 else False
        s = s * (-1) if negative else s

    # If string, convert to integer (depending base number system)
    if type(s) == str:
        s = int(s, get_base(s))
    elif type(s) == float:
        return "Can't do float yet"

    # Make an array of every single number we have got
    n = [int(c) for c in str(s)]

    # If not wanted data as packed, then adding extra 0000, make array
    pack = "0000 " if not packed else ""
    bcd = [pack + format(d, '04b') for d in n]

    # Add sign to the end, positive 1100 and negative 1101
    sign = "1100" if not negative else "1101"
    bcd.append(sign)

    # Return value as BCD coded array
    return bcd

print( to_bcd("0xFFFFFF") ) # base 16
print( to_bcd("0o6701") ) # base 8
print( to_bcd("123") ) # base 10
print( to_bcd(-623) ) # base 10, negative
print( to_bcd("0b1010110", packed=False) ) # base 2, not packed