Access code: It identifies the master so that slaves within the radio range of two masters can tell which is traffic for them. It is a 72-bit field, that contains synchronization bits.
Header: The 54-bit header contains an 18-bit header that is repeated 3 times for a total of 54 bits. It allows the receiver to remind all three copies of each beat and reject the ones that do not have a majority.
Address field: The address field in the header identifies which of the eight devices the frame is intended for.
Types field: Types field identifies whether it is an ACL, SCO, pull or null frame types, the types of error correction used in the data field and how many slots long the frame is
Flow bit: It is used for primitive types of flow control and is asserted by the slave when its buffer is full and cannot receive any more data.
ACK bit: ACK bit is used to piggyback an acknowledgment onto a frame
Sequence bit: It is used to number the frame to detect re-transmission in a stop and wait for a protocol. It is followed by an 8-bit checksum.
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| Bluetooth frame structure |