use constant {
 
    DEFAULT_QUEUE       => 0x03,  # bits 1-0 (0-3)
    MAX_QUEUE           => 0x03,
 
    DEFAULT_POLARITY    => 0x00,  # bit  3
    MAX_POLARITY        => 0x08,
 
    DEFAULT_RATE        => 0x00,  # bits 7-5
    MAX_RATE            => 0xE0,
 
    DEFAULT_MODE        => 0x100, # bit  8
    MAX_MODE            => 0x100,
 
    DEFAULT_GAIN        => 0x200, # bits 11-9
    MAX_GAIN            => 0xE00,
 
    DEFAULT_CHANNEL     => 0x4000, # bits 14-12
    MAX_CHANNEL         => 0x7000,
};