CSC 161 Grinnell College Fall, 2013
Imperative Problem Solving and Data Structures

Laboratory Exercise: Using the Scribbler 2


The goal of this lab is to introduce the Scribbler 2 robot to students.

Getting Started with the Scribbler 2

In this lab, you will experiment with the Scribbler 2 robot's sound capabilities, as well as practice writing and compiling programs that use the robot.

For every program using the Scribbler 2 robot, you first must connect to the robot. At the end of the program (before return 0;), you will disconnect from the robot. The command to connect to the robot is rConnect("/dev/rfcomm0") . This opens a connection to the robot using the port /dev/rfcomm0 . Later in the lab, you will experiment with what happens when the port is not included. The command to disconnect from the robot is rDisconnect() . Here, you do not need to state any port.

Hint: Don't forget to include the library MyroC.h at the beginning of every program.

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 to 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 emacs with the command:

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

  4. Compile the program by typing in the terminal:

      gcc -lMyroC -o scribblerlab scribblerlab.c 
  5. Run it in your terminal by typing:


Experimenting with Connections

  1. 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.

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


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

  /* function for sending tone to the robot */
  void rBeep (double duration, int freq);
  1. 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?

  2. 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.

Write your own program: Music

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

    • Hint: The pitches for various notes can be found using Wikipedia or in the example programs for today.

For those with extra time...

  1. Look in the MyroC.h header file and 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.

Feedback Welcome

Development of laboratory exercises is an iterative process. Prof. Walker welcomes your feedback! Feel free to talk to him during class or stop by his office.