Bluetooth is the term used to describe the protocol of a short range (10 meter) frequency-hopping radio link between devices. These days many products already use bluetooth to communicate for example :Mobile phone with ear phone
Hi-fi with MP3 player
PC with Mobile Phone
Air-conditioner with Mobile Phone
Many microcontroller such as PIC and Rabbit already integrate Bluetooth with their product to enable fast design and development.
Bluetooth radio modules operate in the unlicensed ISM band at 2.4GHz, and avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet.
Bluetooth is the name given to a new technology using short-range radio links, intended to replace the cable(s) connecting portable and/or fixed electronic devices. As a result there is no more hassle to use cable that need to be link at a short distance.
Its key features are robustness, low complexity, low power and low cost. Designed to operate in noisy frequency environments, the Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust.
Compared with other systems in the same frequency band, the Bluetooth radio hops faster and uses shorter packets.
There are 7 layers in Bluetooth protocol stack:
1. Radio Layer
The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2.4 GHz ISM band.
2. Baseband Layer
This layer describes the specification of the Bluetooth Link Controller (LC) which carries out the baseband protocols and other low-level link routines.
3. LMP Layer
The Link Manager is used by the Link Managers (on either side) for link set-up and control.
4. HCI Layer
The Host Controller Interface provides a command interface to the Baseband Link Controller and Link Manager, and access to hardware status and control registers.
Logical Link Control and Adaptation Protocol supports higher level protocol multiplexing, packet segmentation and reassembly, and the conveying of quality of service information.
The RFCOM protocol provides emulation of serial ports over the L2CAP protocol.
The SDP provides a means for applications to discover which services are provided by or available through a Bluetooth device. It also allows applications to determine the characteristics of those available services.