Many of the embedded systems developed today need some sort of wireless communication. Many of them do not require long distance communication and are designed by hardware engineers who are not RF specialists. To answer this particular need, serial port to Bluetooth adapters have appeared on the market.
The Bluetooth link ensures a reliable connection, and is already embedded in many applications that exist. Therefore, adding such a Bluetooth module to your application would enable it to communicate over a decent distance of up to 100m to a great variety of laptops, PDAs or desktop computers. These modules are designed in such a way that they take the design strain completely off the hardware guy: he does not need to have any prior knowledge of Bluetooth. Al he needs to do is to interface its embedded design to one of these off-the-shelf available modules through simple UART or RS232. The module does the rest!
The National Semiconductor LMX9838 Bluetooth Serial Port module is a fully integrated Bluetooth 2.0 baseband controller, 2.4 GHz radio, crystal, antenna, LDO and discreets, combined to form a complete small form factor (10 mm x 17 mm x 2.0 mm) Bluetooth node. It has the appearance of an IC and it is the smallest such serial to Bluetooth adapter that I have found and used. It provides a broad range of configurations and it may be used in a large variety of applications, from simple cable replacements to more sophisticated communication systems based on UART frames and checksums. The entire weight and seriousness of National Semiconductor is behind this module and its small factor and versatility recommend it for many applications. Bear in mind to put solder mask in between the pins, when designing the PCB footprint.
Just a bit bigger than the LMX9838, the RN41 from Roving Networks is still a small form factor, low power, highly economic Bluetooth radio for OEM’s adding wireless capability to their products. The RN41 supports multiple interface protocols, is simple to design in and fully certified, making it a complete embedded Bluetooth solution. With its high performance on chip antenna and support for Bluetooth® Enhanced Data Rate (EDR), the RN41 delivers up to 3 Mbps data rate for distances to 100M. Designers can easily customize their application using up to 8Mbits of flash memory. The RN41 is the perfect product for engineers wanting to add wireless capability to their product but don’t want to spend significant time and money developing Bluetooth specific hardware and software.
The eb101 surface mount Bluetooth serial module from A7 is a highly integrated and easy to use Bluetooth solution designed for low cost and reliability. All components of the Bluetooth stack are implemented onboard so that additional host processor code is not required. Once a connection to another Bluetooth device has been established, the link has the appearance of a cabled serial connection eliminating the need for special wireless protocol knowledge. Simple UART communication facilitates the interface between the host processor and the eb101 radio. This UART interface may be used to discover, connect, and communicate with other Bluetooth devices through simple ASCII commands. EasyConnect provides the option for a drop-in cable replacement solution without having to issue commands. The addition of a simple push button and LED provides all the control necessary to establish and maintain a wireless connection.
Bluemore106 from the Italian company Eikon is a compact Bluetooth dongle based on Bluesmall202 module especially designed for wireless UART/RS232 cable replacement. It's provided with a standard 2,54mm male connector where are available 5V/3,3V Input, UART signals (3,3V and 5V TTL levels), RS232 and 3 I/Os. You can wire it or add a Female connector on your PCB to add Bluemore106 as wireless option.
The HPS-110 produced by Data Link Communications is a ready-to-use short-range wireless connectivity solution for industrial applications. It provides an economic and powerful way of cable replacement for the serial communication systems. Amongst it features we may count: Bluetooth v1.1 compatible, Bandwidth: 1Mbps, Output Power: max +20dBm(100mW), Rx Sensitivity : -84dBm, Coverage : 100m, Temperature Range : -20 ~ 75° C. Warning: this module does not include an antenna, it only provides an SMA connector to which you may attach one. Given this fact and its current price, I would qualify it as rather expensive…
This BlueCOM Bluetooth module commercialized by Merlin Wireless is supplied as a plug-in daughter board, and can be easily integrated into existing board level designs. The Bluetooth module incorporates all the software and hardware you need to implement a wireless link. No specific knowledge of Bluetooth is required and the wireless link is 'transparent' to the host system. From a PC or PDA the link becomes a virtual COM port. Antenna is integrated on the board.
The LM400 surface-mount modules (designed by LM Technologies), is a user-friendly device which has a 12-pin UART configuration. This enables the engineer to upgrade his equipment to a Bluetooth SPP RS232 configuration far more easily than re-designing the PCB. It also means you can build one board and retro-fit the Bluetooth module, making upgrades quick and easy.
Price: £29.99 (from Merlin Wireless)
The Sena manufactured Parani-ESD200 and Parani-ESD210 are a Class 2 type of Compact Embedded Bluetooth Serial Modules for RS-232 cable replacement. By default, they support 30 meters of wireless transmit distance. The Parani-ESD210 has an extension option so that users can extend the transmit distance up to 300 meters using optional antennas, but the ESD200 has a simple onboard chip antenna which makes using this module a breeze.
Price: £35 (from Merlin Wireless)
Grid Connect manufactures the FIREFLY, which is an economical Serial-to-Bluetooth wireless cable replacer that can quickly and easily be added to many devices with a RS232 serial port, providing a wireless connection to another Bluetooth or FIREFLY adapter. All Grid Connect Bluetooth devices are CLASS 1 which means they have a distance range of 330 feet (100 meters). The FIREFLY is simple to use and plugs directly into your male (DTE) or female (DCE) port of your computer/device and connects using wireless Bluetooth technology to another FIREFLY, BluePort, BluePlug, or other Bluetooth compatible device. Although the antenna is included, bear in mind these are rather RS232-to-Bluetooth, rather than UART-to-Bluetooth adapters, so if you want to use them on embedded systems you will need voltage level conversion. The price is quite high.
The OEM SERIAL PORT ADAPTER™ 311/331 series designed by Connectblue is a complete set of different Bluetooth modules specially designed to make the integration an easy task. Interesting enough, it is advertised for the automotive temperature range (which to my knowledge is -40 to +85 Celsius) but then it explicitly indicates a range of only -30 to +85Celsius. The antenna is integrated and the interface voltage levels are suited for UART rather than RS232. Apart from the common SPP profiles this module includes a series of other Bluetooth profiles too, like DUN, FTP and OPP. The price is not specified.
Repost: May 19th, 2009