Troubleshooting Dim LED

Using Arduino LEDs and Multiplexing
1

I'm working on this project where I have correctly wire 9 LEDs to the arduino and make certain LEDs flash so that it corresponds to a song.

My problem is that when I edit the code to turn on/off certain LEDs they all work perfectly fine, except for port 10 which instead of blinking bright like the rest of them blinks very very dim.

I have tried everything to fix this

-change LED
-change resistor/wires/arduino/breadboard/computer

Code:

int ledPins[] = {2,3,4,5,6,7,8,9,10};

void setup()
{
int index;

for(index = 0; index <= 7; index++)
{
pinMode(ledPins[index],OUTPUT);

}
}

void loop()
{
digitalWrite(ledPins[8], HIGH);
delay(500);
digitalWrite(ledPins [8], LOW);
delay(500);
}

If anyone could help me get my light bright again, please let me know

Thanks in advance

2

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OK, so you have 9 pins in the array:

greg81200:

int ledPins[] = {2,3,4,5,6,7,8,9,10};

then you only set the first 8 pins to OUTPUT:

greg81200:
for(index = 0; index <= 7; index++)
{
pinMode(ledPins[index],OUTPUT);

}

greg81200:

 digitalWrite(ledPins[8], HIGH);  

delay(500);
 digitalWrite(ledPins [8], LOW);
 delay(500);

Since the 9th item in the array wasn't set to ouput, you are turning the internal pull-up resistor on and off with the above code rather than setting the pin HIGH and LOW as you expected, thus the dim LED.

Here's how you can make your for loop automatically handle any number of items in the array:

for(index = 0; index < sizeof(ledPins) / sizeof(ledPins[0]); index++)
3

Thanks so much for the help, this worked!

I was also able to finish my project, if anyone wants to see it the link is: