Interaction of two bricks on one robot?

A reader of Die NXTe Ebene has asked the following question:

In order to control more than three motors resp. more than four sensors on my robot, I'm using two NXT bricks. How can these two bricks interact?
One answer that I know of is Bluetooth. Are there other ones?


Brian Davis said…
I can think of a number of ways. First and formost, I'd say use BlueTooth, as that can be used to send complex imformation fairly rapidly, and not use any of the other input/output ports. But since that has already been mentioned...

2) Have one NXT "beep" in morse code to the other NXT, which uses a sound sensor. Of course, this needs to use an input port and sensor on each NXT for two-way communication, and might have problems in noisy environments.

3) Use a light sensor to "look" at the LCD screen of the other NXT. The NXT can communicate by changing the state of the LCD screen, all black or all white (the light sensor probably needs to be at an angle, to avoid direct reflection issues). Again, this takes a sensor & port on each NXT for two-way communication.

4) Have each NXT control a light sensor, and point the light sensors at each other. By toggling the light sensor state from "ambient" to "reflected" (turning the LED on/off), you can again send binary messages between the bricks. But, again you are taking an input port on each.

5) Don't have an input port? If you have a free output port on each NXT, have each connected to a motor, and the two motors mechanically coupled. Now to send a message, a NXT sends a series of "Motor" commands to turn the shared mechanism back and forth. Again, two-way communication, using output instead of input ports.

6) For one way communication, the number of ways goes up dramatically: all of the above methods, but also things like using a motor to turn a multi-shaded disk in front of a light sensor to send information. Or using a motor under control of one NXT to push a touch sensor on another, etc.

To paraphrase LEGO... what will you build/invent? :-)

Brian Davis
Anonymous said…
Sounds like he's just trying to find ways to make three NXTs communicate, like we've been doing for months.

The guys on the other side of the pond are already struggling...
Unknown said…

Not bad, Steve, not bad. :-)
Yet, in this particular case, the "reader" asking the question was a genuine one (and not connected to the Great Trans-Atlantic MCP Challenge at all). As a matter of fact, we aren't in need for cheap tricks on this side of the pond. ;-)

Unknown said…
Can anybody help me? I'm trying to connect my 2 nxt bricks using bluetooth, but I am not been able to do it, because I can only send messages in one direction. Thanks

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