Connected LED to 3V3 instead of GND

Troubleshooting
1

Hi,

I just got my core.

I was trying out the first project “Blink and LED”. See http://docs.spark.io/examples/

However, instead of connecting the LED to GND, I connected it to 3V3. The LED lighted up.

Subsequently, when I correctly connected the LED to GND, the LED would not light up again.

Did I just spoil my core?

Can someone advise?

Thanks.

2

You probably reversed the LED but it’s fine since blinking still works! The core is OK :smiley:

3

Hi Kenneth,

Thanks for the prompt reply.

Would you know why the LED would not light up again when I connect it correctly and run the program? (I have verified that the LED is working)

When I do a spark call digitalWrite “D1,HIGH”, I get a -1. Not sure if that means anything.

4

Hi @Kane,

It’s really easy to burn out an LED if you overpower it, the Core is probably fine, but it’s possible you let out the magic smoke from the LED. :slight_smile:

Thanks,
David

5

Are you trying with Tinker App?

Check that you are connected like this:

D1 -----> LED+ (longer leg) ----------LED- ------------ Resistor ------- GND

A sample code to flash will be:

void setup() {
 pinMode(D1, OUTPUT);
 digitalWrite(D1, LOW);
}

void loop() {
 digitalWrite(D1, LOW);
 delay(500);
 digitalWrite(D1, HIGH);
 delay(500);
}
6

Hi @Dave,

I have checked that the LED is working fine.

However, I cannot get the LED to blink or light up when I run the program. Just wondering if the pins are ok?

Regards

7

Hi @Kane,

Although it’s unlikely, you could destroy a GPIO pin by shorting 3v3 to that pin while it’s set to OUTPUT and being pulled LOW.

Thanks,
David

8

Dear @Dave,

I see. Is there a way to check the pins using a multimeter or any diagnostic software?

Regards

9

@kenneth,

Ah, I see what is the problem. I connected the resistor between D0 and LED+.

The LED is flashing now. :smile:

Thanks so much for your help. I was stumped for so long.

Regards

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