Arduino Dimmable LED - Linear Equations

 Dimmable LED Project

 

This brings up the subject of Linear Equations.

 0 to 1023 - this is the read value (potValue)

0 to 255  - this is the write value range. (LEDvalue)

 

we need to read one value range and convert to another value range. 

 

Led Val = y axis

Pot Val = x axis

m= (y2 -y1)/(x2-x1)

m = (LED Val2 - LED val 1) / (pot val2 - potVal 1)

m = (255-0) / (1023-0) = 255/1023

or

y-y1 =m(x-x1)

or

LED Val - LED val 1 =m(pot val - potVal 1)

LED Val - 0 =m(pot val - 0)

LED Val =m(pot val)

 LED Val =m * pot val

 

Thus 

LED Val = (255/1023)pot val

 

 

 The code:

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// declare your variables
int potPin=A1;// 0 to 255
int gPin=6; // green pin
int potVal; // 0 to 1023 - potentiometer
float LEDVal; // will calculate it depending on potVal
 
void setup()
{
  pinMode(potPin, INPUT);
  pinMode(gPin, OUTPUT);
  Serial.begin(9600); // opens serial monitor
 
}

void loop()
{
  potVal=analogRead(potPin);
  LEDVal=(255./1023.)*potVal;
  analogWrite(gPin,LEDVal);
  Serial.println(LEDVal);
}

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Thanks to Paul McWhorter (Tutorial 14)

https://www.youtube.com/watch?v=7wKdxsvXAFo

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