BCC calc in simplicity is just xoring the uid byte by byte starting from 0, and using the outputted xor from the first byte for the second byte so on and so forth
xor-ing is lining up the binary and if the number above and below are the same, value is 0 and if theyre different its 1
0000 0000
0000 0001 = 01
0000 0001 XOR = 0000 0001 = 01
0000 0001
0000 0010 = 02
0000 0011 XOR = 0000 0011 = 02
0000 0011
0000 0011 = 03
0000 0000 XOR = 0000 0000 = 00
0000 0000
0000 0100 = 04
0000 0100 XOR = 0000 0000 =4
bcc = 04 for UID of 01020304