Yes that is what I mean: each byte interpreted as LSB first (i.e. the first bit is least significant bit of first byte; 9th bit is LSB of second byte etc.), sum bytes 1 - 12, you will get byte 13.
Yes that is what I mean: each byte interpreted as LSB first (i.e. the first bit is least significant bit of first byte; 9th bit is LSB of second byte etc.), sum bytes 1 - 12, you will get byte 13.