Arduino Duemilanove: PWM Pins inconsistant

Forum 2005-2010 (read only) Hardware Troubleshooting
1

on pins 3, 5, 6, 9, 10, 11, the brightness of leds plugged into those pins are inconsistent when set using the command: analogWrite( pin , 255);

Pins 3 and 11 are at full brightness, while pins 5, 6, 9, and 10 seem to be the same brightness when pins 3 and 11 are set as : analogWrite( pin , 2 );

Is this normal, and if so, is it possible to fix?

2

Pins 3 and 11 are at full brightness, while pins 5, 6, 9, and 10 seem to be the same brightness when pins 3 and 11 are set as : analogWrite( pin , 2 );

i hope you meant analogWrite(pin, 255);

Read it with a voltmeter and post the results.

3

I'm unable to find a voltmeter. This is a new unit, and I only have 5 LEDs with the same type resistor on each.

4

You said the resistors are the same. Are all of your LEDs the same color and part type? If not, did you try swapping LEDs to see if it's due to differences? Not all LEDs have the same operating characteristics.

There might be slight differences between PWM pins, due to the differences in their internal timers and comparators, but I'm talking less than 1 or 2%. Shouldn't be noticeable on LEDs except in rare conditions.

5

All the LEDs are the same: Green. Whenever I switched the LEDs, it was the same result. 3 and 11 are bright while the others are dim.

6

Are you mixing the polarity of the LEDs?

7

No.

And when I do mix the polarity intentionaly, the LED that has been switched doesn't even get lit up.

Also:
Only having 1 LED at a time does not effect brightness.

8

Did you remember to set the pins to an output mode?

9

yes