Arduino Mega LOW voltage pin wont drop to Zero

Development Tools IDE 1.x
1

Hi all;
Two pins of my Arduino mega won't drop to zero voltage in LOW state (A1 and D48)

:frowning: :frowning: :frowning:
Any idea???

2

Show the code that you're using to test. Is anything connected to those pins?

3

Nothing connected to all pins;

I tried many codes:

use this code to put all the pins at the low state:

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:
  for (int X = 0; X<=68; X=X+1)
  {
  pinMode(X, OUTPUT);
  digitalWrite(X, LOW);
  }
}

void setup() {

  pinMode(48, OUTPUT);
  digitalWrite(48, LOW);

}

void loop() {


  
}
4

Sorry, forgot to ask earlier. How do you know that they don't drop? Multimeter? Which voltage does it read?

5

Thanks for your response;
I read voltage with a voltmeter
A1 = 2.2 v
D48 = 4.8 v

All other pins = 0.2 ~ 0.5 v (in low state)
:confused:

6

Sounds like the part has been damaged, probably through electrical abuse (voltages higher than Vcc, lower than ground on pin, or excessive current through pin; the former is very good at doing that, the latter less so)

7

Try as suggested here, or just try configuring and testing pin 48 independently to see if it makes a difference.
I don't think you want to mess with pins 0 and 1 (RX/TX) and pin numbers above 53.