I just recieved my arduino UNO a few days ago. My problem is, that with digitalWrite LOW I get 1.2V and digitalWrite HIGH I get 3.6V on pin13, set as output. If I get it right, these voltages should be 0v and 5v respectively. What can the problem be?
Are you loading the pin with any circuit? The on-board LED will pull pin 13's HIGH
to a little bit less than 5V, but not that much.
How are you measuring the voltage?
BTW post the code you are using...