Robotics+Communication

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Bluetooth 1. Once Bluetooth is enabled on the NXT bricks, devices are able to see other Bluetooth-enabled devices in the vicinity of 10m, including cell phones, PDAs and other teams' bots. Thus, it is very vital for you to assign unique names to your NXT bricks by using the LEGO Mindstorms software. Names can be assigned through the tool in the Mindstorms software that is used for controlling the connection between your NXT and the computer. 2. After the NXT brick is turned off, the Bluetooth connection is lost. After turning the NXT brick back on, the connection can be reestablished between any two bricks by using the "search" utility under the Bluetooth menu of the NXT brick. If a Bluetooth connection has previously been established between two NXT bricks, then passphrases do not have to be entered again (see tip #3). There are two vital initialization steps. One is to provide a passphrase between any two communicating NXT bricks for security and sync purposes. Here, an initial passphrase is exchanged between the two NXT bots. After passphrases are set once, the bricks will remember them even if they are turned off. The other step is done after the initial exchange of passphrases, where the NXT needs to do a search for setting up the communication channel. A communication channel is chosen between the two devices having the same passphrase. (Please see the 4 [|th] tip below as well.) An NXT bot is able to see (i.e., "search") other NXT and Bluetooth-enabled devices in its vicinity. However, an NXT has no capability to discern other Bluetooth devices before the passphrase setup, except by name. Thus, the need for naming as in tip #1. 3. NXTs communicate over channels. There are 4 different channels for Bluetooth communication. Please make sure that the connection channel chosen in your software program is the same as the one chosen when setting up the connection between the two bots. 4. NXT bricks have a built-in functionality to send files (such as compiled code) to other NXT bricks. However, please note that transfers are only possible from a master to its slaves.

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