I have bought a new 'SunFounder Arduino uno R3' and started learning, the first lesson was 'Blinking LED' of course.

I have done it all, connected Jumper-Wires and the Sensor and the LED light, I wrote the code:

const int ledPin = 9;
void setup()
void loop()

BUT NOTHING HAPPENS !!!, I checked out every thing over and over, it just does not work ??? Every thing is well about the board and the UNO R3 it is new. I have checked the code and the connections and checked the Device Manager to know that the serial port of the arduino is 'COM3'... I dont know what is wrong with it ?!!

  • have you tried the built in LED on pin 13? – BrettAM Jan 5 '16 at 21:46
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    No wire should be necessary; leave the arduino disconnected from everything but the PC and set ledPin to 13. – BrettAM Jan 5 '16 at 21:49
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    As mentioned by BrettAM, pin 13 is good for testing since nothing needs to be hooked up. Also, be sure that the Arduino IDE has been set to the correct COM port and that the model of the device has been set correctly in the menus before uploading the sketch. You did upload the sketch, right? (compiling is not enough) When you upload the sketch, does the serial transfer light blink rapidly for a brief moment to show that the upload is taking place? – Michael Jan 5 '16 at 21:58
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    Can you post a good quality, well focused picture of your setup, showing where all the wires are connected? – Ricardo Jan 8 '16 at 16:58
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    Oh sorry Guys I just figured out that the bread board sends electric power in line so I have to connect every wire with the same line that fits (+side of the LED or -side) yeah I didn't know that... So sorry for westing ur time and thanks u all. – Osama_Mrdoud Jan 8 '16 at 19:16

In these cases it helps to break down the problem in pieces.

If the internal LED on pin 13 blinks with your code it means that the software side is OK so far (code, Arduino type, compiling, uploading etc), so I suggest looking at the physical side of things.

Do you have a multimeter available? If so, connect it between pin 13 and ground and it should show you if the output works.

Finally, is the LED working? When you connect it between 5V and GND (with a resistor!) it should light up.

  • Sorry for westing ur time friend, I just didn't know that the bread board sends power in lines my bad sorry and Thank u... – Osama_Mrdoud Jan 8 '16 at 19:17

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