Using the Scribbler 2

This lab introduces the Scribbler 2 robot to students and combines the Scribbler 2 with eSpeak.

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:

Open a terminal window and move to the lab directory you are using for this course.
Start emacs with the command:
```
emacs scribblerlab.c &
```
Troubleshooting: If your emacs editor opens with a split screen, and if you find the split screen annoying, you might want to review the section on Modifying emacs in the lab on Linux basics.
Copy the program scribblerlab.c to your emacs window. Don't forget to save it every time before you compile.
Compile the program by typing in the terminal. Two approaches are possible.
- For the MyroC environment, use the line:
```
clang -I/home/walker/MyroC/include -L/home/walker/MyroC/lib -lMyroC -lbluetooth -ljpeg -o scribblerlab scribblerlab.c
```
- Alternatively, you can use the command
```
make scribblerlab
```
  Troubleshooting:
  - If the clang command prints errors that there are undefined references to `rConnect', `rBeep', and/or `rDisconnect',
    - Be sure you have included the library flags -lMyroC -lbluetooth -ljpeg in your clang command.
    - Be sure you included the MyroC material into your .bashrc file, as described in the early parts of the lab on Linux Basics
  - If the clang command works, but the make command indicates errors with undefined references to `rConnect', `rBeep', and/or `rDisconnect', be sure you have copied the Makefile file to your current directory, as described in the Makefile section of the lab on Linux Basics
With either approach for compilation, run the program in your terminal by typing:
```
./scribblerlab
```

Experimenting with Connections

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 empty string "". Replace the port when you are done and save the program.
Delete the include statement. What happens when you try to compile? Replace the include statement and save (you could do this with Emacs' undo command).

Sound from the Scribbler 2 Robot

Here is the documentation for rBeep() from the development 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 freq);

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?
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

Write a program that connects to the robot, makes it beep a short tune that sounds good to you, then disconnects from the robot.
Note: The pitches for various notes can be found on numerous online sources or in the example programs for today.

Optional Activity: Playing a Duet

Look at the MyroC documentation.

Find the function rBeep2(). Write a simple program and test how rBeep2() works. If you finish this, go through the rest of the documentation, explore, and test other procedures that interest you.