use Data::Dumper;
my $counter = 'a0000000';
my @x= unpack('(B3)(B3)(B2)(B)(B)(B)(B2)(B3)BBBBB(B11)', pack('H*', $counter));
print Dumper(\@x);

##</code><code>##

$VAR1 = [
          '101',
          '000',
          '00',
          '0',
          '',
          '',
          '',
          '',
          '',
          '',
          '',
          '',
          '',
          ''
        ];