Example sketch Blink looks like not working.

I tried to run the example sketch Blink but I saw that the led L was already blinking before to run the sketch. Further, changing the sketch's values (times delay of High and Low) nothing changed. After closing the sketch, the led was still bilinking. What is the trouble?

The led at pin 13 is also called the system led. When the Arduino is reset (or powered on, or the serial monitor is opened) the bootloader blinks the led a few times. After that the sketch starts running.

Changing the delay for the led should change how the led blinks. Did you see an error message ? Have you selected the board and the microcontroller and the serial port ?

When you close the sketch, it it still running on the Arduino board. So as long as the Arduino board is powered with the USB connected, it keeps on running.

There is no such thing as "closing a sketch" so I wonder if you have got some of your concepts mixed up.

You need to open the blink example in the Arduino IDE. Then you need to upload the sketch to your Arduino while it is connected via the USB cable. The LED connected to pin 13 will flash quickly while the program is being uploaded as will the Tx and Rx LEDs. When the upload is completed the LED on pin 13 will flash slowly all the time the Arduino is connected to the PC - including if you disconnect it and reconnect it without uploading the program again.

If it does not work like the above, post the actual code you are using in case there is some error.


Hi, I'm with Robin2 too!! Is your sketch being uploaded to the Arduino? Have you set the IDE for verbose output on compile and upload, in which case you should see something happening at the bottom of the screen, including any ERROR messages.

Check the TX & RX leds on upload...



For Robin2

I did the exact steps you said above, of course (the same ones recommanded in the guide), so I worried. Ad I said in my post, the led L blinks indefinitley (not just few times) and changing times delay it blinks with the same frequency. The code I used is that one included in the examples of Arduino IDE 1.0.6, that's

// the setup function runs once when you press reset or power the board void setup() { // initialize digital pin 13 as an output. pinMode(13, OUTPUT); }

// the loop function runs over and over again forever void loop() { digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level) delay(1000); // wait for a second digitalWrite(13, LOW); // turn the LED off by making the voltage LOW delay(1000); // wait for a second }

After having loaded the sketch, the state bar shows this message: avrdude: stk500_getsync(): not in sync: resp=0x00


After having loaded the sketch, the state bar shows this message: avrdude: stk500_getsync(): not in sync: resp=0x00

This means your code is NOT being uploaded to the Arduino!! Have you selected the right board and serial port from the Tools menu?? you may have to try 2-3 ports until you find the right one.

Hope it helps, Regards


For Cactusface

You're right, the port was wrong. Because when I opened the first time the IDE, it reported already COM1 I tought it recognized by itself the correct COM. Now all seems ok.

Thank you

Hi cirochiaiese, Glad to hear it worked, we all get this problem, especailly I find with Windows (7) as it seems to re-asign USB ports everytime you power the PC up. It's a bit dumb really.