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Bluetooth Packet Formats

 

A standard blueooth packet

ACCESS CODE [72]

HEADER [54]

PAYLOAD [0-2745]

* size in bits

ACCESS CODE	Access code is used for synchronization, DC offset compensation and identification.
HEADER	Header contains link control (LC) information.
PAYLOAD	Payload carries voice and data fields of upper layers.

Access code format

PREAMBLE [4]

SYNC WORD [64]

TRAILER [4]

* size in bits

PREAMBLE	Preamble is a fixed zero-one pattern of 4 symbols used to facilitate DC compensation.
SYNC WORD	Sync word is a 64 bit code used for timing synchronization.
TRAILER	Trailer is a fixed zero-one pattern of four symbols. Trailer may be used for DC compensation also.

Header format

AM_ADDR [3]

TYPE [4]

FLOW [1]

ARQN [1]

SEQN [1]

HEC [8]

* size in bits

AM_ADDR	3-bit active member address to distinguish active members in a piconet.
TYPE	4-bit type code to distinguish between 16 different types of packets.
FLOW	1-bit flow control over ACL link.
ARQN	1-bit acknowledgement indication of success of transfer of the packet.
SEQN	SEQN bit provides a sequential numbering scheme to order the data packet stream.
HEC	8-bit header error check to check the header integrity.

Payload format

HEADER [8-16]

BODY [Indicated in header]

CRC CODE [16]

* size in bits

HEADER	Header is one or 2 bytes longer. Only data fields have a payload header.
BODY	Payload body includes the user host information. The length os the body is indicated in the length field of the payload header.
CRC CODE	The 16-bit cyclic redundancy check code is generated by the CRC-CCITT polynomial 210041 (octal).

Payload Header for single slot

L_CH [2]

FLOW [1]

LENGTH [5]

* size in bits

Payload Header for multi-slot

L_CH [2]

FLOW [1]

LENGTH [9]

UNDEFINED [4]

* size in bits

L_CH	L_CH determines the logical channel used.
FLOW	Flow indicator is used to control the flow at the L2CAP level.
LENGTH	Length indicator indicates the number of bytes in the payload excluding the payload header and the CRC code.

DV packet format

ACCESS CODE [72]

HEADER [54]

VOICE FIELD [80]

DATA FIELD [32-150]

* size in bits

ACCESS CODE	Access code is used for synchronization, DC offset compensation and identification.
HEADER	Header contains link control (LC) information.
VOICE FIELD	Voice field contains synchronous (voice) content carried like a SCO packet.
DATA FIELD	Data field contains data carried like a ACL packet.

Format of FHS payload

PARITY BITS [34]

LAP [24]

UNDEFINED [2]

SR [2]

SP [2]

UAP [8]

NAP [16]

CLASS [24]

AM_ADDR [3]

CLK_(27-2) [26]

PAGE SCAN MODE [3]

* size in bits

PARITY BITS	The 34-bit parity bits form the first part of the sync word of the access code. These bits are derived from the LAP.
LAP	The 24-bit LAP contains the lower address part of the unit that sends the FHS packet.
UNDEFINED	Undefined as of now.
SR	SR is the scan repetition field and indicates the interval between two consecutive page scan windows.
SP	SP is the scan period field and indicates the period in which mandatory page scan mode is applied after transmission of inquiry response message.
UAP	UAP contains the upper address part of the unit which sends the FHS packet.
NAP	NAP contains the non-significant address part of the unit which sends the FHS packet.
CLASS OF DEVICE	Class of device has not been defined yet.
AM_ADDR	This 3-bit field contains the member address the recipient shall use if the FHS packet is used at call-setup or master-slave switch.
CLK_(27-2)	This field contains the value of the native clock unit that sends the FHS packet.
PAGE SCAN MODE	This field indicates which scan mode is used by default by the sender of the FHS packet.