1

I have an assignment wherein we have 8 LEDs connected to an Arduino Uno which has a switch. These LEDs light up according to the johnson counter but every time I turn the switch off it should reset back to the start. An example is if I turned the switch off while the pin is at 8 going back to 1 , then when i turn it on it should be back to 1 again. I got the 1 to 8 reset part right but the 8 to 1, I'm having trouble solving.

Here is my code:

int pin;
int sw3 = 10;

void setup() {
  // put your setup code here, to run once:
  for (pin = 2; pin <= 9; pin++) {
    pinMode(pin, OUTPUT);
  }
  pinMode(sw3, INPUT);
}

void loop() {
  pin == 2;
  if (digitalRead(sw3) == HIGH) {
    for (pin = 2; pin <= 9; pin++) {
      digitalWrite(pin, HIGH);
      delay(200);
    }
  }
  else {
    digitalWrite(pin, LOW);
  }

  delay(200);

  for (pin = 2; pin <= 9; pin++)
  {
    digitalWrite(pin, LOW);
  }
  delay(200);

  if (digitalRead(sw3) == HIGH) {
    for (pin = 9; pin >= 2; pin--) {
      digitalWrite(pin, HIGH);
      delay(200);
    }
  }
  else {

    digitalWrite(pin, LOW);
  }

  delay(200);

  for (pin = 9; pin >= 2; pin--) {
    digitalWrite(pin, LOW);
  }
  delay(200);
  {
    if (digitalRead(sw3) == LOW) {
      digitalWrite(pin, LOW);
    }
    else {
      digitalWrite(pin, LOW);
    }
  }
}
  • I'm not able to comprehend what your problem is. The code also doesn't seem to do a johnson counter. Could you rephase your question, and maybe mark in your code where your problem is? – Gerben Sep 2 '18 at 18:36
1

Some fixes:

pin==2; should only be 1 = here. == is a comparison.

pinMode(sw3,INPUT); make this INPUT_PULLUP, to turn on the internal pullup resistor

if(digitalRead(sw3)==HIGH){ change this to LOW, and wire your switch/button to connect the pin to GND when pressed. The internal pullup will unsure the pin is HIGH when not pressed, and the button/switch makes it LOW when pressed. The pin is thus not allowed to 'float' and return a random HIGH or LOW.

  • 1
    I think they are using an external pull-down. – Gerben Sep 2 '18 at 18:29
  • the pin == 2 is probably the problem. – CrossRoads Sep 2 '18 at 23:30

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