I am not sure why the ON LED and the L LED keeps blinking on my Arduino.

I was just trying to implement a simple circuit using breadboard, and everything worked fine until I unplugged one wire with the power turned on. I accidentally made the wire touch something in the Arduino, and the LED in the breadboard became extremely bright. Then the ON LED and the L LED in the Arduino started to keep blinking, and I cannot download code to Arduino anymore. I am using IAR and IAR says AT91SAM3 reset: Communication breakdown after resetting target. Abort debug session?.

I think maybe there is a short cut when the wire touched the Arduino... But how can I determine what the problem is? Thank you very much, I am totally new to Arduino and has very limited knowledge about hardware...

  • It's dead. Buy another. – Majenko Nov 12 '17 at 13:19

You should split your problem in pieces. Like you cannot get communication with your Arduino again, so check first:

  • If you plug in the Arduino / USB, do you get a message on your computer?
  • Is it visible in the systems manager?
  • Is it visible by the IDE?
  • If you connect an adapter (12 or 9V), does it make a difference?
  • If you try another Arduino, does it work like it should be?

If you are a beginner, always make sure:

  • Never change any wiring with the Arduino on
  • Never have dangling wires, if you do not need a wire for the time being, either remove it completely or put it in a breadboard hole that is not used
  • Never change components with the Arduino on
  • After rewiring/adding/changing components, double check first

Update for comment below because it does not fit as comment: To buy a cheap/fake (but working) Arduino uno, e.g. Arduino Uno from Aliexpress

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  • Hi, thanks for your advice! The Arduino is visible to the IDE, and I will get another Arduino to check tomorrow. It worked fine before, everything changed since the touch. – Jiahao Cai Nov 12 '17 at 12:30
  • I'm afraid something is not working in the Arduino anymore ... and unless you are more expert it might be useful to try to fix it, otherwise buy a new one ... I bought some from China, much cheaper and if something breaks it cost just a few euro. – Michel Keijzers Nov 12 '17 at 12:32
  • What an expensive lesson:-( Is it proper to ask how buy it from China here, can you tell me? I am at Sweden. – Jiahao Cai Nov 12 '17 at 12:45
  • First I want to say not everybody likes it and it has some disadvantages. First you have to wait from 2 to 10 weeks, also they are fake (so might have some small differences, so far I didn't have many problems). But you can go to e.g. aliexpress and buy the one in my link (does not fit). Also these have a different chip and you probably need to install CH340G drivers (very easy to install). – Michel Keijzers Nov 12 '17 at 13:12
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    Another method to avoid having to buy a new board when you screw something up, is get one with a microcontroller that can be taken out. Half the time, you'll only have damaged the controller and the board survived. Controller is less expensive than a full board. All the first ones had it, not sure about the later ones. Often times you don't need the M3 and an Atmega would've been fine. – Mast Nov 12 '17 at 18:29

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