IF statement doesn't work (using Arduino, Firmata, controlP5)

rkxkzk

IF statement doesn't work (using Arduino, Firmata, controlP5)

in Integration and Hardware • 4 months ago

I'm using Processing 1.5.1 on a Windows7-64bit machine.

import controlP5.*;
import processing.serial.*;
import cc.arduino.*;
Arduino arduino;
ControlP5 cp5;
int ledPin = 12;
color mycolor = color(0);
int sliderValue = 100;
boolean sliderValueLargetThanHundred = false;
void setup() {
arduino = new Arduino(this, Arduino.list()[0], 57600);
arduino.pinMode(ledPin, Arduino.OUTPUT);
size(700, 400);
cp5 = new ControlP5(this);
cp5.addSlider("sliderValue")
.setPosition(20, 200)
.setRange(0,255)
.setSize(255, 20)
.setValue(100)
;
}
void draw() {
background(mycolor);
if(sliderValue > 100) arduino.digitalWrite(ledPin, Arduino.HIGH);
else arduino.digitalWrite(ledPin, Arduino.LOW);
}
public void sliderValue(int value) {
sliderValueLargetThanHundred = value > 100;
}

When I run this code, even if i change sliderValue by dragging slider, there is no change to the LED connected to Arduino board.

If I use a boolean variable(sliderValueLargerThanHundred) instead of "sliderValue > 100", the light is turned on and off as I expected.

Why does that IF statement only works with a boolean variable?

Replies(4)

GoToLoop

Re: IF statement doesn't work (using Arduino, Firmata, controlP5)

4 months ago

Perusing your code, I can't see any place where field variable sliderValue

happen to have its stored value changed!

So, it's eternally = to its initial value of 100!

Now, something that is slightly frowned upon. You have both a field & a function sharing the same name!

Thus, sliderValue refers to both an int field variable & also method sliderValue(int value)!

Of course, Java knows how to differentiate a variable from a function

for the lack or presence of open parenthesis just after its label name!

Although for other languages like JavaScript that wouldn't be allowed at all.

So pay attention when coding elsewhere!

Well, although I dunno much about library controlP5,

I believe you've registered method sliderValue() as a trigger event.

So it is there you should change the value of field sliderValue:

void sliderValue(int value) {

sliderValue = value;

}

That would probably fix your code!

Now, a cool trick! Replace block if/ else @ lines # 32 & 33 by this 1:

arduino.digitalWrite(ledPin, sliderValue > 100 ? Arduino.HIGH : Arduino.LOW);

And, this recent post below is also related to Arduino. If you wanna take a look there...:

http://forum.processing.org/topic/help-me-optimize-my-code-please-arduino-serial-firmata

Well, that's all!

rkxkzk

Re: Re: IF statement doesn't work (using Arduino, Firmata, controlP5)

4 months ago

I know it sounds strange, but since I added a slider controller with a name "sliderValue", the function and the variable with the same name are automatically linked to the controller. So dragging the slider changes the value of int "sliderValue". This is how controlP5 works.

Thanks for your one line solution, I could save one line :) but still it doesn't work with "sliderValule > 100". It works when I change it to the boolean variable.

GoToLoop

Re: IF statement doesn't work (using Arduino, Firmata, controlP5)

4 months ago

Well, you still can try to debug current value of variable sliderValue!

Insert this line below just before my compact 1-line if/else statement.

And check out whether it ever changes from its initial 100 value:

print(sliderValue + " - ");

rkxkzk

Re: Re: IF statement doesn't work (using Arduino, Firmata, controlP5)

4 months ago

Actually I have code for checking the value, just omitted here. It's definitely changing.

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