EncapsulationDay 11

Computer Programming through Robotics

CPST 410

Summer 2009

7/1/09 Harry Howard, CPST 410, Tulane University

2

Course organization

Course home page (http://robolab.tulane.edu/CPST410/)

Lab (Newcomb 442) will be open for practice with 3-4 Macs, but you can bring your own laptop and all robots.

Encapsulation

My Blocks vs. Functions

My Blocks in NXT-GKelly §26 ‘My Block is your block’

Open the Mindstorms app.

7/1/09 Harry Howard, CPST 410, Tulane University

5

A silly program

Tribot, do the following slowly (at 50% speed):Spin right for a rotation,and then show a happy face.Move forward for a second, and then beep.Spin left for a rotation,and then say “good job!”.

SillyProgram.rbt

7/1/09 Harry Howard, CPST 410, Tulane University

7

Analysis

Note that the program really has three parts,but the structure of the program does not

show this division.There is a way to encapsulate each part into

its own block, called a My Block.

7/1/09 Harry Howard, CPST 410, Tulane University

8

My Blocks

Select the first part (the first three blocks). Go to the Edit menu of the Mindstorms NXT application

and choose “Make a New My Block”. Give the block an informative name like StartUp and a short

explanation. Click the ‘Next’ button and choose a picture for it, such as one of

the motor icons. Click ‘Finish’.

You have just created your first MY BLOCK. It should have occupied the place of the originals in your

program, as shown in the next slide.

SillyProgram.rbt with StartUp

Keep on going

Note that if you double click on StartUp, it opens up in a new piece of graph paper, as if it were a program itself.

MY BLOCKS are stored in the Custom palette (aquamarine equals sign).

Now turn the other two pairs of blocks into My Blocks.

7/1/09 Harry Howard, CPST 410, Tulane University

11

SillyProgram.rbt with MY BLOCKS

Functions in NXC

Close the Mindstorms app,

and open BricxCC.

7/1/09 Harry Howard, CPST 410, Tulane University

13

SillyProgram.nxctask main (){ OnFwdSync(OUT_BC, 50, 100); Wait(1000); Off(OUT_BC); GraphicOut(0, 0, "faceopen.ric"); Wait(500);

RotateMotor(OUT_BC, 50, 360); PlayTone(440, 500); Wait(500);

OnFwdSync(OUT_BC, 50, -100); Wait(1000); Off(OUT_BC); PlayFile("Good Job.rso"); Wait(700);}

7/1/09 Harry Howard, CPST 410, Tulane University

14

Functions = My Blocksp. 149ff

Syntax: insert ‘void’ from Programreturn_type name(argument_list){

“statements”}

If there is no return type, use ‘void’.Define a function before the main task.

7/1/09 Harry Howard, CPST 410, Tulane University

15

SillyProgram.nxc with one function

void StartUp(){ OnFwdSync(OUT_BC, 50, 100); Wait(1000); Off(OUT_BC); GraphicOut(0, 0, "faceopen.ric"); Wait(500);}task main(){

StartUp();RotateMotor(OUT_BC, 50, 360);PlayTone(440, 500);Wait(500);OnFwdSync(OUT_BC, 50, -100);Wait(1000);Off(OUT_BC);PlayFile("Good Job.rso");Wait(700);

}

7/1/09 Harry Howard, CPST 410, Tulane University

16

SillyProgram.nxc with 3 functions

void StartUp(){ OnFwdSync(OUT_BC, 50, 100);

Wait(1000);Off(OUT_BC);GraphicOut(0, 0, "faceopen.ric");Wait(500);

}void ImportantStuff(){ RotateMotor(OUT_BC, 50, 360);

PlayTone(440, 500);Wait(500);

}void ShutDown(){ OnFwdSync(OUT_BC, 50, -100);

Wait(1000);Off(OUT_BC);PlayFile("Good Job.rso");Wait(700);

}task main(){

StartUp();ImportantStuff();ShutDown();

}

7/1/09 Harry Howard, CPST 410, Tulane University

17

Next time

Parallelism.