Looks to me like you are trying to do what is commonly called BCD (for binary codes decimal). You are also actually converting a binary number which you happen to conveniently encode in hexadecimal for shorter typing.

Look at left and see button "Code Library". Click that and notice that there are two links to Binary to BCD convert routines. See below:



These are for 16-bit data but you should easily be able to adapt it to 8 bit data, even if that adaptation is as simple as passing your existing byte made into 16 bits by attaching another byte of zeros as the "upper byte".

Michael Karas