Inputs:  Light and Touch Sensors

Student Activity Instruction Sheet 1.10

The RCX has three outputs labeled 1, and 3.  You can connect sensors to these ports since your Lego kit comes stocked with two touch sensors and a light sensor.  The touch sensors have a yellow button sensor that connects to the RCX with the same connectors used with motors. The light sensor is a blue brick that has a built-in connector permanently attached.  The RCX can sense the light intensity picked up by the light sensor and measure it on a scale of one to one hundred. 

Procedure 1:  Light Sensor

1.      Press the On-Off button on the RCX to turn it on

2.      Connect the light sensor to Port 2

3.      Notice how an arrow appears pointing to Port 2

4.      Press the Run button

5.      What happens?  Does the light turn on?

6.      Press the PRGM button once

7.      Press the Run Button

8.      What happens?  Does the light turn on?

9.      Press the PRGM Button

10.  Press the Run Button

11.  What happens?  Do you see a light this time?

12.  What appears on the screen as you move the light sensor around

13.  Press the PRGM button

14.  Press the run button

15.  What happens?  Do you still have a light on the light sensor?

16.  What appears on the screen with this program?

17.  Take note that when the light sensor gets closer to an object, arrows appear on the screen.  This is a testing activity, once programming of the RCX units is done with the computers, those light sensors will create a number on the screen above the arrows that you were seeing appear on the RCX screen. 

Procedure 2:  Touch Sensor

1.      Locate two Wire Connectors from the Kit

2.      Locate the two touch sensors in the kit.

3.      Make sure that the two motors are connected to Outputs A and C on the RCX Car (this should already be completed based on the RCX car - Activity 1.8)

4.      Connect the two Wire connectors to Ports 1 and 3 on the RCX

5.      Connect the other end of the wire connectors to the two Touch Sensors

6.      Press the PRGM button until program 2 is selected.

7.      Pres the green RUN button.

8.      The two motors should start to rotate.

9.      Press the touch sensor connected to port 1.

10.  Next, touch the sensor connected to port 3.

11.  What happens to the motors?

12.  Press the run button again.

13.  Disconnect the touch sensors and reconnect them in different orientations (connect them in different locations than before)

14.  Press the RUN button once more.

15.  Has anything changed?

16.  How would the touch sensors be used on a car?  What is their purpose?