Help with Arduino

[himelspike]

Hello everyone, I am working on a class project using labview with arduino uno to turn on/off a LED and also change the brightness using a virtual slider/knob directly from the VI. I am pretty new to labview so having really hard time. Can anyone suggest how to build the block diagram. I will greatly appreciate your feedback. Thank you.

[Ben_J1]

Himelspike,

  With the "slider" are you referring to some kind of linear potentiometer? So one easy to use way of controlling brightness of a single LED through LIFA is to use PWM to throttle the brightness of an LED. Here is a quick example of doing that:

The PWM functionality of LIFA takes advantage of Arduino's analogWrite function which is limited to only the PWM pins of the Arduino Uno.

Try it and let me know how it goes.

-Ben

[himelspike]

Thank you so much Ben for your reply. But are you saying that I have to connect a potentiometer to the arduino PWM pin? I was looking for a way to virtually control the brightness from the VI without actually using a potentiometer hardware.. Is it possible ?

[Ben_J1]

Himelspike,

  This method would not need a physical slider. The Duty Cycle of the PWM signal would change the brightness of the LED.

-Ben

[hrh1818]

The object in the block diagram labelled Duty Cycle ( 0 to 255 ) is your slider. You will need to add a control to your front panel that matches this functionality.

Your LED is connected to PIN 3,  In this block digram the output signal driving your LED is a pulse width modulated , PWM signal.  When  the duty cycle of the PWM signal is low  the LED will be dim and when the duty cycle is high the LED will be bright.  Duty cycle is the ratio of (On time)/On time + Off time). You will need to add a resistor in series with the LED when you connect the LED to Pin 3.  I suggest a 220 ohm resistor. The resistor limits the current through the LED.  Excessive current can quickly burn out a LED.   Don't forget the  ground connection for the LED and the resistor.

Howard

[himelspike]

Yes! It worked. Thank you so much Ben and Howard !!! You guys rock I never thought I will have my problem solved so quickly !! Amazing