... split it to bytes.

If this means you want to end up with an array (or string) of byte values for each pair of hex digits, consider pack:

c:\@Work\Perl>perl -wMstrict -MData::Dump -le
"my $s = '00000FFEDFF6';
 print qq{'$s'};
 ;;
 my @bytes = split '', pack 'H*', $s;
 dd \@bytes;
"
'00000FFEDFF6'
["\0", "\0", "\17", "\xFE", "\xDF", "\xF6"]
[download]

Update: Another validation test to make sure you have an even number of hex digits in the source string might also be a good idea.