Blink problem

Hi. newbie to Arduino I bought the ONE and lcd keypad shield. Trying to make someting I have two leds (red and green) and for a stupid test I modified the blink example /* Blink Turns on an LED on for one second, then off for one second, repeatedly.

This example code is in the public domain. */

void setup() { // initialize the digital pin as an output. // Pin 13 has an LED connected on most Arduino boards: pinMode(9, OUTPUT); pinMode(12, OUTPUT); }

void loop() { digitalWrite(9, HIGH); // set the LED digitalWrite(12, LOW); delay(1000); // wait for a second digitalWrite(9, LOW); // set the LED off digitalWrite(12, HIGH); delay(1000); // wait for a second } The problem is that leds blink all together...Where is the problem???? I also tryed to compile with an old software version but it is the same

How did you connect them?

Gnd is common with a resistor and one to pin 9 and other to pin 12. I also notice that if i dont use one of the two led and tell the arduino to blink pin 13 and other pin, if i use only the led on the board the leds blinkright...if i connect the normal led on the pin 13 also , the two leds blink as one....

Gnd is common with a resistor and one to pin 9 and other to pin 12.

A picture is going to be necessary, because this description is not any where near adequate.

"Ground is common with a resistor" is nonsense. We expected that you connected one LED to pin 9 and the other end to pin 12. But, which leg of the LED is connected to the pin? Where is the other leg connected?

I have not an image at the moment

I'll try to explain better.

pin 9 ------------------- led green gnd------resistor-------- led red pin12 --------------------

I think is clear. Thank you

(disclaimer: sw guy speaking here)

That way the current flowing through the resistor is different if one or both leds are on. And that's a Bad Thing (tm), as the v=ri across R will vary too. Is this correct ?

It should be like this:

pin 9 -----resistor-------- green LED -------- ground

pin12 -----resistor-------- red LED ------------ground

Be sure you have the LED anode (long pin) to the resistor, and the cathode (flat spot) to ground.