BluetoothTM General Information White Paper is the registered trademark of Atmel Corporation, 2325 Orchard Parkway, San Jose, CA 95131 Rev. 1993A-11/00 White Paper Introduction The Bluetooth wireless technology is the world's new shortrange RF transmission standard for small form factor, lowcost, short-range radio links between portable or desktop devices. The technology promises to eliminate the confusion of cables, connectors and protocols confounding communications between today's high tech products. Mobile phones, pagers, laptops, PDAs, digital cameras and more, all now have a common structure for communicating across their product platforms. Bluetooth wireless technology provides a solution to a continuously increasing need for mobile freedom. The increase in the number of users, and the constant shrinking, of portable computers, as well as the trend towards the replacement of desktop computers from portable ones, form an ideal market environment for a solution that eliminates the annoying cable and its limitations regarding flexibility and range. Bluetooth is a low-cost, low-power, secure and robust standard for short-range connectivity. The technology has been designed for ease of use, simultaneous voice and data and multi-point communications. It supports a range of 10 meters, which can be increased up to 100 meters with the use of an amplifier. The initiative for the specification belongs to the Bluetooth Special Interest Group (SIG) (www.bluetooth.com) which was founded in February 1998. At the start, it consisted of Ericsson Mobile Communications, Intel, IBM, Toshiba and Nokia Mobile Phones. This group represented the diverse market support that was needed to generate good support for the new technology. With over 2,000 companies now part of the Bluetooth Special Interest Group (SIG), tomorrow's products will fall into one of two categories: those that are enabled with Bluetooth and those that are not. Apart from the definition of the radio and link protocols, the job of the Bluetooth SIG is to ensure the same interpretation of the Bluetooth standard by all future vendors. Therefore, it has defined a number of user models and prot oc o l pr o fi l e s , a s w e l l as s p e c i fi c p r o c e d ur e s fo r interoperability verification. 2 White Paper How Does It Work? Any Bluetooth system has four basic parts: a radio (RF) that receives and transmits data and voice; a baseband or link control unit that processes the transmitted or received data; link management software that manages the transmission; and supporting application software. The Bluetooth radio is a short-distance, low-power radio that operates in the unlicensed spectrum of 2.4 GHz. This spectrum is shared by other types of equipment (e.g. microwave ovens). In order to avoid interference, the Bluetooth specification employs Frequency Hopping Spread Spectrum (FHSS) techniques. Using a nominal antenna power of 0 dBm, the range is 10 meters (33 feet). Optionally, a range of 100 meters (328 feet) may be achieved by using an antenna power of 20 dBm. Data is transmitted at a maximum gross rate of up to 1 Mbps. Protocol overhead limits the practical data rate to a little over 721 kbps. Interference or being out of range may further decrease the achievable data rate. Baseband is the hardware that turns received radio signals into a digital form, which can be processed by the host application. It also converts digital or voice data into a form that can be transmitted using a radio signal. The baseband processor takes care of converting data from one form to another (such as voice to digital data), compressing it, putting it into packets, taking it out from packets, assigning identifiers and error correction information and then reversing the entire process for data that is received. In Bluetooth, the baseband function is called the link controller. The link manager software runs on a microprocessor and manages the communication between Bluetooth devices. Each Bluetooth device has its own link manager, which discovers other remote link managers, and communicates with them to handle link setup, negotiate features, authenticate QoS and to encrypt and adjust data rate on link, dynamically. The application software is embedded in the device that operates an application over the Bluetooth protocol stack (see Figure 1). This software allows the PDA, mobile phone, or keyboard to do its job. All Bluetooth devices must have compatible sections in their Bluetooth stack, so that all Bluetooth devices will be able to interoperate with each other. Figure 1. The Bluetooth Protocol Stack Service Discovery Protocol (SDP) Applications & OS Drivers Link Control & Adaptation Protocol (L2CAP ) Host side Host Controller Interface Driver Host Controller Interface Transport layer (HCI transport ) Host - BT device boundary (PCMCIA, USB or UART) Host Controller Interface Transport layer (HCI Transport) Host Controller Interface (HCI) Link Manager Protocol (LMP) BT device side Link Controller (LC) Bluetooth PHY (Baseband Processor and RF ) 3 The Components of a Bluetooth System All Bluetooth designs require an antenna, a transceiver and a baseband controller that meet the Bluetooth specification (see Table 1). A microcontroller (MCU) to run the link control, link manager and Host Controller Interface (HCI) and/or Logical Link Control and Adaptation Protocol (L2CAP) firmware, as well as memory to store the firmware, configuration information and short-term operating information are also needed. Alternatively, developers can choose to implement protocols up to and including, HCI on the microcontroller, and to implement the HCI driver and L2CAP on the machine that hosts the Bluetooth chipset. Quite a few combinations for the Bluetooth hardware are possible. These range from single-chip solutions (RF, Baseband, Microcontroller and memory integrated into one chip), up to four-chip solutions (RF, Baseband, Microcontroller and memory in separate chips). Table 1. Bluetooth V1.0 Specification Summary Radio Frequency 2.45GHz (ISM band) Spread Spectrum Technique Frequency Hopping Hop Frequencies 79 (spaced 1 MHz apart) Hop Rate 1,600 hops/sec (625 s dwell time) Transmitting Power 1 - 100 mW Max. Range 10 m (0 dBm)/100 m (20 dBm) Max. Gross Bit Rate 1 Mbps Max. Practical Bit Rate (ACL-Symmetric) 433.9 Kbps Max. Practical Bit Rate (ACL-Asymmetric) 723.2 Kbps/57.6 Kbps Bit Rate (SCO) 64 Kbps Max. Piconet Units 8 (1 master - 7 slaves) Power Save Modes Hold-Sniff-Park 4 White Paper Atmel Offering Atmel, a Bluetooth SIG member, is one of the world's few companies that offers systems designers a complete, single-vendor Bluetooth solution - RF, baseband/ microcontroller, Flash, software and firmware. Atmel has its main chip fab facilities in Colorado Springs, Colorado, in Rousset, France and Heilbronn, Germany and has extensive experience refining its process technologies to achieve the system-level integration of all the components of the Bluetooth standard. Currently, Atmel offers a complete three-chip solution: baseband and microcontroller functions into one chip, RF transceiver and Flash memory. Our roadmap includes the eventual integration of these three chips into a single-chip solution. Figure 2. Atmel's AT76C551 Bluetooth Module White Paper Atmel's Bluetooth ICs Atmel's Bluetooth baseband controller, in conjunction with a 2.45 GHz transceiver, provides a low-chip count solution for a wide range of digital communication devices and comp u t e r p e r i p h e r a l s . T h e b a s e b a n d i s b a s e d on a n AR7TDMI TM processor, includes 64K bytes of internal SRAM and supports three different interfaces: PCMCIA, USB and UART. Some versions will also include a 16-bit voice Codec capable of either log PCM or CVSD voice coding. For the RF part, Atmel offers T2901, which is a 0 dBm RF transceiver with integrated synthesizer and VCO. The transceiver supports Bluetooth's 10 meter "Pico-Cable" specification and features a proprietary image rejection mixer and advanced closed loop modulation. It does not require mechanical tuning. Also, Atmel offers T7024, which is a 20 dBm RF front end supporting Bluetooth's 100 meter "Mega-Cable" specification. The chip features 23 dBm POUT typ, low noise (2.0 dB typ), high gain and ramp controlled output. Atmel's Bluetooth Firmware and Software ATMEL provides customers all firmware on the device side. L2CAP and Service Discovery Protocols on the host side can be made available to qualified customers. Software is available up through the HCI transport layer, as well as drivers for PCMCIA and UART interfaces. Drivers for the USB interface will soon be available. Figure 3. ATMEL Bluetooth Firmware Architecture Model non-critical modules non-critical modules executed by ARM in executed by ARM in user mode user mode Bluetooth Bluetooth Device Device Bluetooth Bluetooth Link Link Manager Manager Host Host Control Control Interface Interface Logical LogicalLink Link Control & Control & Adaptation Adaptation Protocol Protocol Host Host Bluetooth Device Bluetooth Device Driver Driver Voice VoiceCodec Codecdriver driver time-critical modules time-critical modules executed by ARM in executed by ARM in interrupt mode interrupt mode Bluetooth Bluetooth Link Controller Link Controller USB USBdriver driver UART UARTdriver driver PCMCIA driver PCMCIA driver USB USBdriver driver UART driver UART driver PCMCIA driver PCMCIA driver data Path data Path control path control path 5 Atmel Headquarters Atmel Operations Corporate Headquarters Atmel Colorado Springs 2325 Orchard Parkway San Jose, CA 95131 TEL (408) 441-0311 FAX (408) 487-2600 1150 E. Cheyenne Mtn. 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Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimhatsui East Kowloon Hong Kong TEL (852) 2721-9778 FAX (852) 2722-1369 Japan Scottish Enterprise Technology Park East Kilbride, Scotland G75 0QR TEL (44) 1355-803-000 FAX (44) 1355-242-743 Atmel Grenoble Avenue de Rochepleine BP 123 38521 Saint-Egreve Cedex France TEL (33) 4-7658-3000 FAX (33) 4-7658-3480 Atmel Japan K.K. 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan TEL (81) 3-3523-3551 FAX (81) 3-3523-7581 Fax-on-Demand North America: 1-(800) 292-8635 International: 1-(408) 441-0732 e-mail literature@atmel.com Web Site http://www.atmel.com BBS 1-(408) 436-4309 (c) Atmel Corporation 2000. Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company's standard warranty which is detailed in Atmel's Terms and Conditions located on the Company's web site. The Company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel's products are not authorized for use as critical components in life suppor t devices or systems. Bluetooth is a trademark owned by Telefonaktiebolaget L M Ericsson Sweden and is licensed to Atmel. All other marks bearing (R) and/or TM Printed on recycled paper. are registered trademarks and trademarks of Atmel Corporation. 1993A-11/00/xM Terms and product names in this document may be trademarks of others.