sub frame2packet {
    my @frame = @_;

    my $packet = '';
    foreach my $byte (@frame) {
        my $lowbyte = ($byte & 0x0f) + 65;
        my $highbyte = ($byte >> 4) + 65;

        $packet .= chr($highbyte);
        $packet .= chr($lowbyte);
    }

    return $packet;
}

sub packet2frame {
    my $packet = shift;

    my @chars = split//, $packet;
    my @frame = ();

    # Decode to bytes
    while(@chars) {
        my $high = shift @chars;
        my $low = shift @chars;

        my $val = ((ord($high) - 65) << 4) + (ord($low) - 65);
        push @frame, $val;
    }

    return @frame;
}