The two-button remote control is a very versatile program for controlling Lego robots. It uses a series of touch sensor Switches to determine which behavior you want to trigger. Since the Switches are between a set of Loops, the program loops infinitely, and the behavior of the robot will change every time a different touch sensor is hit.

In this program, the two-button remote is setup to control a car with motors connected to Ports A and C. When only touch sensor 1 is pressed, Motor A spins forward and Motor C spins backward. This will turn the car left or right. When only touch sensor 2 is pressed, the motors are reversed and the car will spin the opposite direction. If both touch sensors are held, the motors go forward. When no touch sensors are held, the car does not move. Remember, each branch of the Switch can control something different. It does not only work for a car. The touch sensors can trigger music, events, even mail to other robots. The possibilities are endless.

This is another version of the two-button remote. 

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Like its smaller cousin, the three-button remote control is a great way to define unique behaviors for your robot. The advantage to the three-button control is that there are now 8 possible behavior combinations, compared to just 4 on the 2-button remote. In addition to forward, left and right motion on our two motor car, it is now possible to move in reverse, and even control a third motor. With so many combinations, it is possible that you don?t need them all. In that case just leave one branch of the Switch empty.

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The advanced proportional control program works the same way as the basic version; however, this code allows the user to vary the proportionality constant. When run, the NXT first displays the current proportionality constant that the later "power" variable will be divided by. Thus, if 4 is shown on the NXT, the proportionality constant will be ? or .25. The constant can be changed by turning the rotation sensor. Only positive values will work. After the constant is set, a press of the touch sensor will "Switch" into the proportional control loop from the basic program. Experiment with different constants. Note the difference between very small constants and very large constants.

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This program uses two touch sensors combined with two Switches--all in an infinite loop--to display a number on the screen. Port 1 adds 1 and Port 2 adds 100. The "adder" variable is set to zero at the beginning of this program.

This code turns on Motor A for two seconds, and then turns it off. Similiar codes can be made by adding motors or changing times.

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There are many ways to stop a car at a black line. Using a light sensor attached to Port 1, the program takes the initial light reading, drives forward (one motor car) and waits for a difference greater than or equal to 5. Once this difference is reached, the Switch stops the NXT and exits the program.

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In this code, sound frequencies are played corresponding to changing light values. Light sensor readings, which fall between 0-100, are placed in a variable and multiplied by the constant 8. The value of that variable, which now falls between 0-800, becomes the frequency in Hz of the sound played. The frequency is also displayed on the NXT.

This program says "Hello." 

This program is works like the Line Follower: Wait for Dark program but it uses a Switch. The program runs a Switch--in a infinite Loop--that runs Motor A and makes sounds when reading light. The program stops Motor A then runs Motor C for 0.25 seconds when reading dark.