3.3V pin isn´t working

Official Hardware UNO Family UNO R3
1

Hello, I´m new to arduino and I might have broke my 3.3V pin. I unfortunately dont have a voltmeter so I can´t tell exacli what is going on, but any LED I connect to it wont work, whitch isnt the case for any other pin. I think that I either accidentally connected it to ground or 5V from external source. Do you know what could be wrong? And how to fix it?

2

Did your LED have a current limiting resistor?

Connect your 3.3V pin up to the A0 pin and run this sketch a few times. If the serial monitor consistently displays a value in the neighbourhood of 675 (assuming a 5V board), your 3.3V pin is likely just fine.

void setup() {
   Serial.begin(115200);
   Serial.println(analogRead(A0));
}

void loop() {
}
2 Likes
3

You can get an inexpensive one for less than the cost of two packs of cigarettes, plus shipping. It's an essential tool that's hard to do without when working with electronics.

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4

The serial monitor showed around 1000. I´ve changed the codde a bit, because it didn´t work for me.
the code:

void setup() {
 pinMode(A0, INPUT_PULLUP);
}
void loop() {
  Serial.begin(115200);
  Serial.println(analogRead(A0));
  delay(100);
}
5

You've just enabled the pullup resistor on A0, ensuring that your analogRead value is meaningless. The default configuration for A0 is fine for this test.

6

Sorry, after removing it it shows value around 60.

7

Then it's toast. Time to buy a new board and be more careful with this one. Or buy two and have a spare.

1 Like
8

Is there any way to save it?

9

It's still good, you just don't have 3.3V

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10

Since you're able to upload sketches, most of the board is still okay(ish - I wouldn't trust it for anything critical). I wouldn't try powering it from the barrel jack, since the 3.3V output is used to determine whether or not to cut off the USB power in that configuration.

But unless you have a hot air station and your SMD rework skills are honed (which, if you're asking the question, the answer is no), the 3.3V output is history.

11

Ok, thank you.

12

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