The $250 Presentation Remote
A pretty simple idea: to use the NXT as an input device to a computer or
laptop. Here is how to accomplish this.
Currently the code uses the NXT as a presentation remote. Its left and
right buttons are used as the left and right buttons on the computer's
keyboard. This allows you to control PowerPoint and Adobe Acrobat presentations.
In the future I plan to implement mouse functionality and other human-interface
To use this code, follow these steps.
Download the NXT program to the NXT.
Both are simple programs.
Find out the port number of serial communication coming from
the NXT. To find out the port number, right click on the bluetooth icon
in the Windows tray, select "Advanced Configuration",
select the "Local Services" tab, and note the COM port of the serial service.
On my machine, it is COM14.
The Windows program is a console program. Run it from
a command shell (start -> run -> cmd). Give the name of the COM port
as an argument. If you run it with no arguments, it will give you
instructions as to how to run it.
Once the system works, you can minimize it.
Use the Bluetooth menu on on the NXT to connect to the computer,
and use channel 1 (the default). You can use "search" under the
bluetooth menu, but you can probably also use the list of connections
(if you already used this NXT with this computer). For the system to
work, you must initiate the communication from the NXT; NXT bluetooth
communication is not symmetric.
Run the NXT program. Clicking the left and right buttons should behave
just like clicking on the keyboard.
It would be wonderful if Lego added instructions or system calls on the NXT to
perform the bluetooth connection; currently you must use the NXT menus
to reconnect everytime you turn it on.
On the Windows side, it should be possible to detect the bluetooth configuration
automatically, but for now I didn't manage to do that.
I assume that the batteries on the NXT would last a long time when it is
only running a program and using bluetooth (that is, when it is not running
any motors), but I don't know that for sure. If anybody finds out how long
they last when the next is used as a remote, let me know.
© 2006, Sivan Toledo