Laboratory Exercise: Using the Scribbler 2 and Basic Input

Goals

This lab introduces the Scribbler 2 robot to students, combines the Scribbler 2 with eSpeak, and provides practice with basic input.

Work Started in Class

Getting Started with the Scribbler 2

In starting work with a Scribbler 2 robot, this lab focuses on sounds (beeps). Later labs explore other capabilities of the Scribbler 2.

Connecting to and disconnecting from the robot

In this exercise, you will download the code for a program that connects to the Scribbler, beeps once, and then disconnects from the Scribbler. Read the program and its annotations to further understand what is happening. You will then copy the program into your emacs file and compile the program on your terminal. Finally you will run the program.
Here are the steps to do these:

1. Open a terminal window and move to the directory you are using for this course.

2. Start aquamacs and open a new file.

3. Copy the program scribblerlab.c to your aquamacs window. Don't forget to save it every time before you compile.

4. Compile the program by typing in the terminal. Two approaches are possible.

   • For the MyroC environment, use the line:

       
     gcc -Wall -Wno-deprecated-declarations -std=gnu99 -pthread -lMyroC -leSpeakPackage  -lMyroC -leSpeakPackage -framework OpenGL -framework GLUT   scribblerlab.c   -o scribblerlab
        

• Alternatively, you can use the command

    
      make scribblerlab 
    

5. With either approach for compilation, run the program in your terminal by typing:

   ./scribblerlab 
   

Experimenting with Connections

6. In the program scribblerlab.c , delete the /dev/rfcomm0  port that is in rConnect() . What happens when you compile and run? Now type hello  into the port. What happens when you compile and run? Do the same for the null string "" . Replace the port when you are done and save the program.

7. Delete the include statement. What happens when you try to compile? Replace the include statement and save.

Sound from the Scribbler 2 Robot

Here is the documentation for rBeep() from 3.1 version of the MyroC.h header file:

/**
 * @brief Beeps with the given duration and frequency
  * @param duration   length of note in seconds
   * @param frequency  frequency of pitch in cycles per second (hertz)
    * @pre              duration > 0.0
     */
     void rBeep(double duration, int frequency);

8. In the original program scribblerlab.c , copy the beep statement and change the frequency to 600, 700, 900, 400, 15000 and 200. Experiment with frequencies. Which frequencies are audible?

9. Now vary the length of the beeps. Copy the beep statement again and this time change the duration to 0.75, 2, 2.5, 3, 3.1, and 4. Listen to what happens.

Basic user input

10. Copy the program quarts-rev.c to your account and compile it (e.g., with gcc).

    1. Run the program several times, entering several integer values.

    2. Describe what happens if you enter a real number (such as 10.5 or 7.89)?

    3. Describe what happens if your input begins with a non-letter (e.g., "the number 23.5")?

    4. Initialize the quarts variable at the start of the program, by changing the declaration to:

       int quarts = 7; 
       

       Now repeat steps 10b and 10c. Can you explain what happens?

    5. What happens if you change the format string for "%d" to "%lf" (without changing any other part of the program?

11. Copy the program quarts-gallons.c to your account and compile it (e.g., with gcc).

    1. Run the program several times, entering integer values for quarts and gallons.

    2. Describe what happens if you enter two real numbers with decimal points (such as "10.5 2.7")?

    3. As with Step 10, initialize variables quarts and gallons to non-zero integer values, and repeat Step 10b. Describe what happens.

Homework

Write your own programs: Beeps and Music

12. Write a program that reads a frequency (an int) and a duration in seconds (a double) and then commands the robot to beep at the given frequency for the prescribed duration.

13. Write a program that connects to the robot, makes it beep a short tune that sounds good to you, then disconnects from the robot.

Scribbler 2 Robots and eSpeak

A challenge arises when trying to test a robot-based program, in which the robot performs several actions — including movement.

• Testing requires the programmer to look at the code to know what is supposed to happen.
• Testing requires the programmer to watch the robot to see what it does.

Even with two eyes, watching both the program and the robot can be difficult. The eSpeak package can help resolve this difficulty.

14. Examine the scribbler-espeak.c program.

    1. Open the scribbler-espeak.c program and copy it to your account.

    2. To compile the program with gcc, you will need to specify both MyroC and eSpeak. Since typing the locations of each package is error prone, you should use the make command:

       make scribbler-espeak
       

    3. Run the program and describe what happens.

    4. Edit the program, make some changes, and compile and run the revised program to check what happens.

Optional Activity: Playing a Duet

15. Look at the MyroC documentation.

    • MyroC data structures (Picture, Pixel)
    • MyroC header file (Web-based format)
    • MyroC header file (C-style format)

    Find the function rBeep2(). Write a simple program and test how rBeep2() works. If you finish this, go through the rest of the header file and see if there is anything else you want to try testing out.