THE PARTICLE COMPUTER DOCU
XBridge:       (Bridge to Ethernet)                   

 

               

What is it?

The network environment

Particles are able to communicate ad-hoc. If two Particles are comming together they instantly can talk to each other. No infrastructure, backbone, configuration or set-up is needed. Additionally Particles can profit from services in the environment if they come near a so called "XBridge" device, that connects the Particles RF AwareCon communication to the Internet world. The XBridge offers full Ethernet connection (100 MBit) and Smart-Its AwareCon communication.

The main task of a XBridge is to offer any Internet enabled device to connect to a Particle and to collect information send by a Particle device. The XBridge also enables Particles to access services and information on the Internet. When transferring information from Particles to the Internet, XBridges add the location to the transferred information so that applications running on the Internet are able to locate Particles. This feature is later used by development tools to maintain an overview over Particles.

Additional services can be placed in the local environment to further support the Particles environment by utilizing the XBridge infrastructure device. E.g. the Particle database service holds history information from all Particles in the environment for later debugging or maintenance reasons. This database can be queried either via a Web-Interface or directly via SQL queries from applications.

The XBridge device provides Internet access to and for Particles. Wireless coverage from one room to 50 meters in house - this depends on the environment and building conditions AND on the antenna. Currently we use "wire" antenna. You can replace this antenna with another 868.35 MHz antenna.

The Functionality

Because the format of Particles packets are not suitable for IP based communication (espcially smaller in size), the XBridge converts the format from the Ethernet to AwareCon and back. Doing so, it enters additional location information of the Particle. These information can later be used by other programs to locate or track Particle devices.

Practical Issues

To let the Xbridge work you simple attach power from a AC/DC converter to it (see power section) and attach a straight Ethernet cable to the XBridge (the same type of cable you use for your PC or laptop computer). Select an input voltage between 4.5 and 12 V and ensure you are using a high quality AC/DC converter. If the XBridge does not start up change the polarization (you can not harm the XBridge device by providing the wrong voltage polarization). A start of the XBridge is indicated by flashing LED lights. It takes some seconds before the XBridge has started. This is indicated by a change of the LED blinking. The XBridge assumes that you have DHCP running on your network. If not, you have to

Some Details

XBridge is part of the Particle infrastructure. The infrastructure supports Particle based applications and provide access for applications to Particles. These applications can run on large variety of computers as PCs or PDAs. Infrastructure is optional for the functionality of the Particles itself but may be required for certain services such as wireless development and maintenance of Particle applications.

The above figure shows a setting with several Particles distributed among rooms of a flat or office environment. Particles can access the Internet by using XBridges infrastructure devices. The main task is to offer any Internet enabled device to connect to a Particle and to collect information send by a Particle device. The XBridge also enables Smart-Its Particles to access services and information on the Internet. For doing so XBridges strip off the RF part of an incoming packet from the Particle RF network, then add a UDP part to the packet and sent it into the network. On the other hand, XBridges receive UDP packets - e.g. from PCs, PDA or laptops - strip off the UDP part, add some RF part and send it to the particle devices.

When transferring information from Smart-Its to the Internet XBridges add the location in RAUM format to the transferred information so that applications running on the Internet are able to locate Particles. This feature is later used by development tools or other services to maintain an overview over Smart-Its Particles. Additional services can be placed in the local environment to further support the Smart-Its environment by utilizing the XBridge infrastructure device.

The Parts

The above picture shows an opened XBridge device. The XBridge device basically consists of 3 parts: The Particle that ist stacked onto the XBridge via an Conan Connector, the Bridge Core and the XPort (fixed soldered onto the XBridge). Each of the components comes with its own CPU and can be programmed separately.

XPort

The XPort contains a ethernet interface, an own CPU, memory etc. and can be used to run user programs. A description of the XPort is available at Lantronix. For configuring the XPort you need a programm called XPort installer, which con be downloaded at the Lantronix site. The XPort is also the place where Particle specific information is configured. Read the Word-Doc description file for more information. Information on how to upgrade the newest firmware of the XBridge can also be found here.

Particle