Light leds using an array

Forum 2005-2010 (read only) Software Syntax & Programs
1

My C is very rusty and I'm trying to light a row of leds one at a time with a common ground. Any help is appreciated.

int ledPin0 =  13;    // LED connected to gnd digital pin 13

int ledR1 [8] = { 9, 3, 2, 12, 15, 11, 7, 6}; // LED connected to vcc for digital pin 13

int vcc = 255;
int gnd = 0;

// The setup() method runs once, when the sketch starts

void setup()   {                
  // initialize the digital and analog pins as an output:
 pinMode(ledPin0, OUTPUT);
 pinMode(9, OUTPUT);
 pinMode(3, OUTPUT);
 pinMode(2, OUTPUT);
 pinMode(12, OUTPUT);
 pinMode(15, OUTPUT);
 pinMode(11, OUTPUT);
 pinMode(7, OUTPUT);
 pinMode(6, OUTPUT);

}

// the loop() method runs over and over again,
// as long as the Arduino has power

void loop()                     
{  
  
  digitalWrite(ledPin0, LOW);   // set common ground for row 1 (pin 13)  
 
  for (int i=0; i < 8; i++)
  {
   if(i=4){                               //Analog pin 15 is controlled by analogWrite function
      analogWrite(ledR1[i], vcc);
      delay(100);
      analogWrite(ledR1[i], gnd);  
   }
      
    else{                         //light up the rest of the leds
        digitalWrite(ledR1[i], HIGH);    // set the vcc to turn on 1,i 
        delay(100);          // wait for a second
        digitalWrite(ledR1[i], LOW);   // set the gnd to turn off 1,i 
        delay(100);
        }
  }

I have it working with a whole bunch of repetition and I'm just trying to minimize this code:

 int ledPin0 =  13;    // LED connected to gnd digital pin 13

int ledPin1 =  9; // LED connected to vcc for digital pin 13
int ledPin3 =  3;
int ledPin5 =  2;
int ledPin7 =  12;
int ledPin9 =  15;
int ledPin11 =  11;
int ledPin13 =  7;
int ledPin15 = 6;

int vcc = 255;
int gnd = 0;

// The setup() method runs once, when the sketch starts

void setup()   {                
  // initialize the digital pin as an output:

}

// the loop() method runs over and over again,
// as long as the Arduino has power

void loop()                     
{
  pinMode(ledPin0, OUTPUT);
  pinMode(ledPin1, OUTPUT);
  digitalWrite(ledPin0, LOW);   // set common ground for row 1 (pin 13)  
  digitalWrite(ledPin1, HIGH);    // set the vcc to turn on 1,1 (pin 9)
  delay(100);          // wait for a second
  digitalWrite(ledPin1, LOW);   // set the gnd to turn off 1,1 (pin 9)
  delay(100);
  
  pinMode(ledPin3, OUTPUT);
  digitalWrite(ledPin3, HIGH);    // set the vcc for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin3, LOW); //
  delay(100);
  
  pinMode(ledPin5, OUTPUT);
  digitalWrite(ledPin5, HIGH);    // set the Ground for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin5, LOW);
  delay(100);
  
  pinMode(ledPin7, OUTPUT);
  digitalWrite(ledPin7, HIGH);    // set the Ground for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin7, LOW);
  delay(100);
  
  pinMode(ledPin9, OUTPUT);
  analogWrite(ledPin9, vcc);    // set the  for the LED
  delay(100);          // wait for a second
  analogWrite(ledPin9, gnd);
  delay(100);
  
  pinMode(ledPin11, OUTPUT);
  digitalWrite(ledPin11, HIGH);    // set the Ground for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin11, LOW);
  delay(100);
  
  pinMode(ledPin13, OUTPUT);
  digitalWrite(ledPin13, HIGH);    // set the Ground for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin13, LOW);
  delay(100);
  
  pinMode(ledPin15, OUTPUT);
  digitalWrite(ledPin15, HIGH);    // set the Ground for the LED
  delay(100);          // wait for a second
  digitalWrite(ledPin15, LOW);
  delay(100);
  
}
2

That is pretty easy.

int ledPins[] = {9, 3, 2, 12, 15, 11, 7, 6}; // LED pins
int ledCnt = 8;

void setup()
{
    for(int p=0; p<lenCnt; p++)
    {
        pinMode(ledPins[p], OUTPUT); // Set the mode to OUTPUT
    }
}

void loop()
{
    for(int p=0; p<ledCnt; p++)
    {
        analogWrite(ledPins[p], HIGH); // Turn an LED pin on
        delay(100);   // Twiddle thumbs for a while
        analogWrite(ledPins[p], LOW); // Turn an LED pin off
        delay(100);   // Twiddle thumbs some more
    }
}

Inside the for block in the loop function, you can take special actions for specific pins, if needed.

Remember, though, that "if(i = 4)" is always true, while "if(i == 4)" is only sometimes true.

Do you have the common connection for all the LEDs connected to a pin? If so, why? The common connection should be to ground.

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