user3892: I am doing the following in setup:
 pinMode(13,OUTPUT);
 digitalWrite(13, HIGH);

When I check with the multimeter, I get an output voltage of 8V rather than 5V. What may be the problem and how do I troubleshoot it?. 

user4143: You have a badly calibrated multimeter. 
Try it on something where you know what the voltage should be, such as a 9V battery and see what it reads.

3892: <p>I am doing the following in setup:</p>

<pre><code> pinMode(13,OUTPUT);
 digitalWrite(13, HIGH);
</code></pre>

<p>When I check with the multimeter, I get an output voltage of 8V rather than 5V. What may be the problem and how do I troubleshoot it?. </p>
 4143: <p>You have a badly calibrated multimeter. </p>

<p>Try it on something where you know what the voltage should be, such as a 9V battery and see what it reads.</p>
