Control Multiple LED Brightness/Dim with One Potentiometer

Other Hardware LEDs and Multiplexing
1

Hi. I am trying to dim multiple LED's using one potentiometer. I am first completing this in TinkerCad. I am able to turn the LED's on and off, but I seem to be missing something as far as controlling the amount of electricity is going to the LED's to control how bright it is. I am trying to keep the code simple, but any advice would be helpful. I am trying to not use the map function.

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image1092Ă—807 161 KB

//Pin Definitions
const int RedPin1 = 4;//Red1 connected to pin 4
const int RedPin2 = 6;//Red2 connected to pin 6
const int GreenPin1 = 8;//Green1 connected to pin 8
const int GreenPin2 = 10;//Green2 connected to pin 10
int potPin = A0;     // Potentiometer pin
int inputValue = 0; // int to keep track of the values coming from the Potentiometer

void setup() {
  // LED pins 
pinMode (RedPin1, OUTPUT);
pinMode (RedPin2, OUTPUT);
pinMode (GreenPin1, OUTPUT);
pinMode (GreenPin2, OUTPUT);
pinMode (potPin, INPUT);
   
}

void loop() {
  // Program multiple LED Lights to Turn ON and OFF
inputValue = analogRead(potPin);    // gets value from sensor

digitalWrite (RedPin1, HIGH);
digitalWrite (RedPin2, HIGH);
digitalWrite (GreenPin1, HIGH);
digitalWrite (GreenPin2, HIGH);
delay (3000);

digitalWrite (RedPin1, LOW);
digitalWrite (RedPin2, LOW);
digitalWrite (GreenPin1, LOW);
digitalWrite (GreenPin2, LOW);
delay (1000);
  
 
}
2

To control the brightness of LEDs you must use analogWrite() instead of digitalWrite().

analogWrite() only works with the Arduino pins that have the ~ symbol next to their pin numbers.

So far, you have succeeded! But why do you not want to use that function?

3

Welcome to the forum

You are reding the pot then ignoring the value that you have read

when you read the pot into an int variable you will get a value between 0 and 1023. To control the brightness of the LEDs they must be connected to PWM pins and you must write a value between 0 and 255 using analogWrite().

To avoid the use of the map() function (why ?) just divide the value read from the pot by 4 and write it to the LEDs

1 Like
4

Thank you for the feedback. I wasn’t sure if the map function was need, but it appears that the map function must be included for the voltage divider and the analogWrite with the PWM pins. I appreciate the help.

Here is my working copy:

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image1444Ă—1308 271 KB

//Pin Definitions
const int RedPin1 = 3;//PWM Pin 3 - Red1 connected
const int RedPin2 = 5;//PWM Pin 5 - Red2 connected
const int GreenPin1 = 6;//PWM Pin 6 - Green1 connected
const int GreenPin2 = 10;//PWM Pin 10 - Green2 connected
int potPin = A0;     // Potentiometer pin
int inputValue = 0; // int to keep track of the values coming from the Potentiometer

void setup() {
  // LED pins 
pinMode (RedPin1, OUTPUT);
pinMode (RedPin2, OUTPUT);
pinMode (GreenPin1, OUTPUT);
pinMode (GreenPin2, OUTPUT);
//pinMode (potPin, INPUT);
   
}

void loop() {

  // Gets the Value from the Potentiometer 
inputValue = analogRead(potPin);  
  
// Map the potentiometer value to the LED brightness range (0-255)
  int brightness = map(inputValue, 0, 1023, 0, 255);
  

  
// Write brightness to each LED individually
analogWrite  (RedPin1, brightness);
analogWrite  (RedPin2, brightness);
analogWrite  (GreenPin1, brightness);
analogWrite  (GreenPin2, brightness);
  
 
}
5

No, use of the map() function is not necessary. Simply divide the value read from the pot by 4 instead, as I previously suggested

6

Also incorrect. There is nearly always more than one way to achieve a feature in your code.

For example

  // Map the potentiometer value to the LED brightness range (0-255)
  int brightness = inputValue / 4;

or

  // Map the potentiometer value to the LED brightness range (0-255)
  int brightness = inputValue >> 2;
1 Like