The Control Byte is used as the primary packet byte in order to route the packet to the most appropriate interpreter. The format is as follows:

Bit 7:5 Bit 4:0
Packet Type Subsystem

Based in the following bit ordering, the bit mask for Packet Type is 0xE0, while it is 0x1F for Subsystem.

Following is the complete list of all possible Control Byte:

Control Byte ( Packet Type (7:5) / SubSystem (4:0) ) Packet Type (7:5) Subsystem (4:0)
0x00 ( 0b000 / 0b00000 ) Response General
0x01 ( 0b000 / 0b00001 ) Response Fusion
0x02 ( 0b000 / 0b00010 ) Response Power
0x03 ( 0b000 / 0b00011 ) Response GPIO
0x04 ( 0b000 / 0b00100 ) Response LED
0x05 ( 0b000 / 0b00101 ) Response ADC
0x06 ( 0b000 / 0b00110 ) Response DAC
0x07 ( 0b000 / 0b00111 ) Response I2C
0x08 ( 0b000 / 0b01000 ) Response SPI
0x0B ( 0b000 / 0b01011 ) Response Recorder
0x0C ( 0b000 / 0b01100 ) Response EEPROM
0x0D ( 0b000 / 0b01101 ) Response Sensor
0x20 ( 0b001 / 0b00000 ) Ack General
0x21 ( 0b001 / 0b00001 ) Ack Fusion
0x22 ( 0b001 / 0b00010 ) Ack Power
0x23 ( 0b001 / 0b00011 ) Ack GPIO
0x24 ( 0b001 / 0b00100 ) Ack LED
0x25 ( 0b001 / 0b00101 ) Ack ADC
0x26 ( 0b001 / 0b00110 ) Ack DAC
0x27 ( 0b001 / 0b00111 ) Ack I2C
0x28 ( 0b001 / 0b01000 ) Ack SPI
0x2B ( 0b001 / 0b01011 ) Ack Recorder
0x2C ( 0b001 / 0b01100 ) Ack EEPROM
0x2D ( 0b001 / 0b01101 ) Ack Sensor
0x40 ( 0b010 / 0b00000 ) Command General
0x41 ( 0b010 / 0b00001 ) Command Fusion
0x42 ( 0b010 / 0b00010 ) Command Power
0x43 ( 0b010 / 0b00011 ) Command GPIO
0x44 ( 0b010 / 0b00100 ) Command LED
0x45 ( 0b010 / 0b00101 ) Command ADC
0x46 ( 0b010 / 0b00110 ) Command DAC
0x47 ( 0b010 / 0b00111 ) Command I2C
0x48 ( 0b010 / 0b01000 ) Command SPI
0x4B ( 0b010 / 0b01011 ) Command Recorder
0x4C ( 0b010 / 0b01100 ) Command EEPROM
0x4D ( 0b010 / 0b01101 ) Command Sensor
0x60 ( 0b011 / 0b00000 ) Data General
0x61 ( 0b011 / 0b00001 ) Data Fusion
0x62 ( 0b011 / 0b00010 ) Data Power
0x63 ( 0b011 / 0b00011 ) Data GPIO
0x64 ( 0b011 / 0b00100 ) Data LED
0x65 ( 0b011 / 0b00101 ) Data ADC
0x66 ( 0b011 / 0b00110 ) Data DAC
0x67 ( 0b011 / 0b00111 ) Data I2C
0x68 ( 0b011 / 0b01000 ) Data SPI
0x6B ( 0b011 / 0b01011 ) Data Recorder
0x6C ( 0b011 / 0b01100 ) Data EEPROM
0x6D ( 0b011 / 0b01101 ) Data Sensor
0x80 ( 0b100 / 0b00000 ) Error General
0x81 ( 0b100 / 0b00001 ) Error Fusion
0x82 ( 0b100 / 0b00010 ) Error Power
0x83 ( 0b100 / 0b00011 ) Error GPIO
0x84 ( 0b100 / 0b00100 ) Error LED
0x85 ( 0b100 / 0b00101 ) Error ADC
0x86 ( 0b100 / 0b00110 ) Error DAC
0x87 ( 0b100 / 0b00111 ) Error I2C
0x88 ( 0b100 / 0b01000 ) Error SPI
0x8B ( 0b100 / 0b01011 ) Error Recorder
0x8C ( 0b100 / 0b01100 ) Error EEPROM
0x8D ( 0b100 / 0b01101 ) Error Sensor