README.txt

These are the labs for the University of Texas BeagleBoard Open Source Design Challenge training (www.ti.com/beagleboardchallenge).

README.txt

The SYSFS entries for the BeagleBoard LEDs are mounted
at "/sys/class/leds".  You'll find "beagleboard::usr0"
and "beagleboard::usr1".  Each of those directories will
have "trigger" and "brightness" entries.

For this lab exercise, attempt to stop USR0 from blinking
and then turn it on steady, then off, then back to the
blinking state.

You'll need two common Unix/Linux tools called "echo"
and "cat".  "echo" allows you to create output to be
sent to the SYSFS entries and "cat" allows you to read
them.  Not all SYSFS entries can be read or written.

1) Start by using "cat" to print out the current state of
"trigger".

2) Change the state of the "trigger" to "none" using "echo".
The syntax of "echo" is roughly:

echo "text to write" > file_to_be_written

3) Change the state of the "brightness" to "1" using "echo".
Observe the USR0 LED.

4) Change the state of the "brightness" to "0" using "echo".
Observe the USR0 LED.

5) Restore the state of the "trigger" to "heartbeat" using
echo.  Use "cat" to see that the state is restored and
observe the USR0 LED.

lab2

lab2.cpp

/****************************************************************
**
** Lab 2
**
** My references in creating this (starting with most recent):
** http://doc.trolltech.com/4.6/qabstractbutton.html#signals
** http://doc.qt.nokia.com/4.6/widgets-groupbox.html
** http://lists.trolltech.com/qt-interest/1997-06/thread00071-0.html
** http://doc.trolltech.com/4.7/moc.html
** http://lists.trolltech.com/qt-interest/2007-06/thread01171-0.html
** http://cartan.cas.suffolk.edu/oopdocbook/html/
** http://doc.trolltech.com/4.3/signalsandslots.html
** http://doc.trolltech.com/4.3/tutorial-t2.html
** http://doc.trolltech.com/3.0/toggleaction-example.html
** http://sector.ynet.sk/qt4-tutorial/my-first-qt-gui-application.html
** http://doc.trolltech.com/4.3/tutorial-t1.html
** http://www.gidforums.com/t-13690.html
** http://doc.trolltech.com/3.0/t1.html
**
****************************************************************/

#include <qapplication.h>
#include <qpushbutton.h>
#include "lab2.h"

void myQtObj::doSomething(bool checked)
{
    // Put your code here to toggle the state of the USR0 LED
    if(checked)
    {
        system("echo 1");
    }
    else
    {
        system("echo 0");
    }
}

int main(int argc, char **argv)
{
    QApplication a(argc, argv);

    QPushButton b("Push me!", 0);
    b.setCheckable(true);
    b.setChecked(false);
    b.resize(100, 30);

    myQtObj c;

    QObject::connect(&b, SIGNAL(toggled(bool)), &c, SLOT(doSomething(bool)));

    b.show();
    return a.exec();
}

lab2.cpp

/****************************************************************
**
** Lab 2
**
** My references in creating this (starting with most recent):
** http://doc.trolltech.com/4.6/qabstractbutton.html#signals
** http://doc.qt.nokia.com/4.6/widgets-groupbox.html
** http://lists.trolltech.com/qt-interest/1997-06/thread00071-0.html
** http://doc.trolltech.com/4.7/moc.html
** http://lists.trolltech.com/qt-interest/2007-06/thread01171-0.html
** http://cartan.cas.suffolk.edu/oopdocbook/html/
** http://doc.trolltech.com/4.3/signalsandslots.html
** http://doc.trolltech.com/4.3/tutorial-t2.html
** http://doc.trolltech.com/3.0/toggleaction-example.html
** http://sector.ynet.sk/qt4-tutorial/my-first-qt-gui-application.html
** http://doc.trolltech.com/4.3/tutorial-t1.html
** http://www.gidforums.com/t-13690.html
** http://doc.trolltech.com/3.0/t1.html
**
****************************************************************/

#include <qapplication.h>
#include <qpushbutton.h>
#include "lab2.h"

void myQtObj::doSomething(bool checked)
{
    const char * fileName = "/sys/class/leds/beagleboard::usr0/trigger";
    FILE * fileTrigger = NULL;

    if(!fileTrigger)
    {
        fileTrigger = fopen(fileName, "w");
    }

    if(!fileTrigger)
    {
        printf("ERROR: unable to open %s", fileName);
        exit(-1);
    }

    if(checked)
    {
        fprintf(fileTrigger, "none");
        fflush(fileTrigger);
        printf("trigger: none\n");
        fflush(stdout);
    }
    else
    {
        fprintf(fileTrigger, "heartbeat");
        fflush(fileTrigger);
        printf("trigger: heartbeat\n");
        fflush(stdout);
    }
}

int main(int argc, char **argv)
{
    QApplication a(argc, argv);

    QPushButton b("Push me!", 0);
    b.setCheckable(true);
    b.setChecked(false);
    b.resize(100, 30);

    myQtObj c;

    QObject::connect(&b, SIGNAL(toggled(bool)), &c, SLOT(doSomething(bool)));

    b.show();
    return a.exec();
}

lab2.h

#include <QObject>

class myQtObj : public QObject
{
    Q_OBJECT

public slots:
    void doSomething(bool);
};

lab2.h

#include <QObject>

class myQtObj : public QObject
{
    Q_OBJECT

public slots:
    void doSomething(bool);
};

lab2.pro

######################################################################
# Automatically generated by qmake (2.01a) Sat Jun 5 06:07:15 2010
######################################################################

TEMPLATE = app
TARGET = 
DEPENDPATH += .
INCLUDEPATH += .

# Input
HEADERS += lab2.h
SOURCES += lab2.cpp

lab2.pro

######################################################################
# Automatically generated by qmake (2.01a) Sat Jun 5 06:07:15 2010
######################################################################

TEMPLATE = app
TARGET = 
DEPENDPATH += .
INCLUDEPATH += .

# Input
HEADERS += lab2.h
SOURCES += lab2.cpp