Problem making new "Illumination Fraction" variable for Color Mixing Lamp tutori

Projects Programming
1

I've successfully completed the "Color Mixing Lamp" tutorial on page 53 of the Arduino Projects Book. Now I'm just tweaking the code to see if I can make some improvements.

I would like to show how much each of the photoresistors contributes to the overall sensor voltage, so that I can express the value in an "Illumination Fraction:" field.

To do this, I've added a few new float variables to the code:

int totalSensorValue = 0;
float redFraction = 0.00;
float greenFraction = 0.00;
float blueFraction = 0.00;

I've also added this to the void loop() section:

totalSensorValue = redSensorValue + greenSensorValue + blueSensorValue;
  redFraction = redSensorValue/totalSensorValue;
  greenFraction = greenSensorValue/totalSensorValue;
  blueFraction = blueSensorValue/totalSensorValue;
  Serial.print("\t Total Sensor Value: ");
  Serial.print(totalSensorValue);
  Serial.print("\t Illumination Fraction: \t Red: ");
  Serial.print(redFraction);
  Serial.print("\t Green: ");
  Serial.print(greenFraction);
  Serial.print("\t Blue: ");
  Serial.println(blueFraction);

Here's the problem. The values I get back are all zero:

 Total Sensor Value: 1062	 Illumination Fraction: 	 Red: 0.00	 Green: 0.00	 Blue: 0.00

What's going on here? I'm using an Arduino Ono R3 with the Aduino IDE 1.0.6. I will post the entire sketch if you need more info.

2

Try something like:

  redFraction = (float) redSensorValue/totalSensorValue;
  greenFraction = (float) greenSensorValue/totalSensorValue;
  blueFraction = (float) blueSensorValue/totalSensorValue;
3

Yes! It's working beautifully now. Thank you luisilva :smiley:

4

Did you know why now work?
In your original code you did an integer division where 3/5 = 0 (with remaining of 3).
By adding the cast for float, you are saying that one operator is float, and so, the operation must be made in float.

5

Yes I can see that now! It was given integers and trying to keep the same format, even though I declared "redFraction, bluefraction, and greenFraction" as floats. I will remember this for future projects. Thank you so much :smiley: