I just got it and tried to use a parallax ping sensor when i first realized the heat issue, i know a little heat is okay but this is too hot to touch, i took off the ping sensor and reset the code (uploaded the blink code) and it still heats up , my power source is a usb so that can't be the issue , whats going on?
What part is getting hot?
If the ATMega heats up, that's usually a sign that a port or two has been blown, and is likely just a matter of time until the whole chip goes.
Do you have a link to the ping sensor? And how did you connect it?
yeah its the atmega i just connected it to the gnd pin 13 and pin 12 , 12 being the signal and 13 being power i tweaked the code so it would work with those pins
ping sensor link?
You connected the power to Arduino pin 13? If not, could you explain in more detail? What went where exactly?
no pin 13 Powered the ping sensor
the grnd is gnd the power is pin 13 then i used 12 as the signal pin
Pin 13, or any other pin for that matter, doesn't provide power. VCC does. Driving it HIGH doesn't constitute 'providing power' to whatever is connected to it. Connect your sensor to VCC (either 5V or 3V3) and GND, then use pin 12 to read the signal.
well thats what i did and it worked , idk if it messed it up or if it was like that
Yeah, you can also put untreated and unfiltered gasoline in your car and it will work. Doesn't mean it's the right way to make it work. Do things properly and you'll find things going a lot smoother. I don't know why it's overheating, but I would certainly start with the way in which you have things connected not being the correct way.
I never noticed heat before , but i never was looking for it , i got it as a present so i don't know what to do
The maximum current you can safely get from an arduino pin is 40mA. So it looks like you fried some of the internal wires inside the chip.
This is now causing heating during normal operation. I fear that the chip has not got long for this world.
Judging by some links I found the sensor uses between 20 mA and 35 mA for its power. That might explain why it worked for a while, but the chip is only designed to provide 20 mA continuously through an output pin.
I suggest you disconnect the power from pin 13, and connect to the pin marked "5V" on the Arduino board instead.
Grumpy_Mike:
The maximum current you can safely get from an arduino pin is 40mA. So it looks like you fried some of the internal wires inside the chip.
This is now causing heating during normal operation. I fear that the chip has not got long for this world.
i think it should work fine with just a high command , anyways , is there anywhere i can buy the chip itself cheap? i have the uno board revision 3
also , will it ruin the board if i keep using it until i get a new chip?
You can buy the Atmega328 from many places, here is one example:
also , will it ruin the board if i keep using it until i get a new chip?
Do you have any major objection to following our advice and powering the sensor from the 5V pin? If so, what is it?
I doubt the board itself will get ruined, I think there is a thermal fuse on the power supply. Having said that, you still need to take care with it.
no i dont but i think its kinda ridiculous that doing that ruined my chip(this is what i get from my understanding) forgive my lack of knowledge , im used to using basic stamps and this is how i was taught
I did a quick search for "basic stamp max current" and was directed to a datasheet for the PIC16C5X which says on page 67:
Max. output current sourced by any I/O pin ... 20 mA
So the Stamp itself can only source (provide) 20 mA (unless it has buffer chips on board). Now you have chosen to not tell us exactly what the part number of the device you are using is, but if it draws 25 mA you would be in trouble on the Stamp as well.
... this is how i was taught ...
I am hoping they did not in fact teach you to "power" your devices from data pins, without at least checking the current requirements. Data pins are for data. You have a power pin a few millimeters away, why not use it?
Having said that, I myself powered a clock chip from a data pin, because I wanted to be able to turn it on and off. But I checked the datasheet, and the clock draws 1.5 mA which is well under 20 mA. Even then people on this forum warned me that the "turn on" surge might damage my chip. That is, the initial "rush" of current to the device when it is powered on.
then why can you power leds?
This is a good question, I'm glad you are thinking about this. 
You can "drive" LEDs providing you use a current-limiting resistor. These are well-documented in various places. Here's an example:
Basically you need a resistor between the LED and the output pin to limit the current being drawn. Again, you shouldn't draw more than 20 mA, but preferably closer to 10 mA if you have a lot of them. There are various limits on the chip: the limit for one pin, the limit for a group of pins, the limit for the whole chip. Bear in mind that internally it has very very thin wires!
If you have been hooking up LEDs without a resistor, well I think I know now why your chip is getting hot! I would stop doing that. Purely as a guide, something like 330 ohms to 1 K ohms would be a ballpark figure for the sort of resistor to use.
Meanwhile, if you provide the part number for your ping sensor (or where you bought it from, exactly) we could explore what current it needs.
thnx , i dont have the part number as i got it from a neigbor who graduated college and gave it to me after ward , all it says is 5v , also would it make a difference if i took off the at mega and just bent pin 13 on the chip so it doesnt touch anything . im assuming not but just wondering
Huh? I think we must be talking about different things here. You have a ping sensor, which when I looked one up had three wires. Gnd, 5V and data.
You are so resistant to the idea of plugging the 5V wire into the 5V pin of the Arduino I am wondering what is going on, really. Can you take a photo?
Pulling the chip out, and bending up pin 13 sounds strange to say the least. Why don't you just not connect to pin 13? I'm not getting what the problem is. If you bend the pin, it is likely to snap and you won't get it back. Plus I doubt anyone here pulls out their chips, and bends pins out of the way.
... i dont have the part number ...
Is there anything at all printed on it?