Arduino Uno with ATMega328P Processor.analogWrite is not working properly in if statement. It changes the brightness of the LED as if there wasn't any if statement at all.

There are 2 potentiometers to create an intervall in which to program increases of the LED brightness, starting at 40% of the maximum. When it's lower than the minimum value, the LED is turned off.

int ledPin = 6;
int sensorPot = 1; // it's a potentiometer for now
int maxPot = 7; // potentiometer 
int minPot = 3; // potentiometer
int fortypercent = 255*0.4;
int brightness = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(sensorPot, INPUT);
  pinMode(maxPot, INPUT);
  pinMode(minPot, INPUT);

void loop() {
  int start = analogRead(minPot);
  int maxVal = analogRead(maxPot);
  int sensor = analogRead(sensorPot);
  if(sensor/4 > start/4) {
  } else if(sensor = baslangic) {
  } else if ((start < sensor < maxVal)) {
    brightness = sensor/4 - fortypercent;
  } else if (sensor = maxVal) {
    analogWrite(ledPin , 255);
  • 1
    Can't execute how? What happens? – jose can u c Apr 9 '18 at 20:01
  • 1
    Of course it can. What problem are you having? What output do you expect from this program? What output do you have instead? – Edgar Bonet Apr 9 '18 at 20:04
  • Sorry, edited question – keser Apr 9 '18 at 20:04
  • Please, be more specific, like “If I set the pot XXX to position XXX I expect the program to do XXX and instead ot does XXX”. – Edgar Bonet Apr 9 '18 at 20:07
  • I updated my question – keser Apr 9 '18 at 20:22


You are comparing sensorValue to see if it's ever less than minValue.

However, you have mapped sensorValue to range from 0 to 255, and minValue is set at 0. How can anything from 0-255 be less than zero?


One of your if statements: else if(sensor = baslangic) is not comparing, but assigning baslangic to sensor. To compare, use ==.

Your other if statement: else if ((start < sensor < maxval)) is wrong. C++ doesn't work this way. Maybe you want: if ((start<sensor) && (sensor<maxval))?

Instead, your statement evaluates like if ( (start<sensor) < (maxval) ), which means you are comparing the TRUE or FALSE of (start<sensor) to the int that is maxval.

| improve this answer | |
  • I am analog reading minValue. – keser Apr 9 '18 at 20:08
  • Indeed. So, what is connected to pin A3 (minPot) and what values from analogRead() is it providing? Use debug statements. I will retract this answer, since I misread the question. – jose can u c Apr 9 '18 at 20:10
  • Sorry for asking not well explained questions... Newbie here... Updated the question – keser Apr 9 '18 at 20:22

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