Arduino does not work When I try to upload a sketch to my Arduino Uno R3 then sometimes I get the following issue:

At the beginning the RX LED flashes three times and then I get errors:

    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xd1
    avrdude: stk500_recv(): programmer is not responding
    avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xd1


Sometimes I get this:

    avrdude: ser_open(): can't open device "\\.\COM3": Odmowa dostępu.


And sometimes Windows does not see the Arduino.

At this site Have I bricked my Arduino Uno? Problems with uploading to board I read that to check the programmer I must to connect RX with TX and GND with RESET pins and then plug Arduino to my computer, open Serial Monitor and write anything and if you receive the same characters from the Arduino, then the programmer and USB cable are OK. It worked for me.

And I have got one more info. When I plug Arduino with USB to my laptop the L led lights. When I press Reset on Arduino nothing happens, it still lights.

I recently bought a new USB cable, and it worked one day and then I could not upload sketches again. I uninstalled and installed drivers, but nothing changed.

This is a short video with my Arduino https://drive.google.com/file/d/0ByeWvrEgy2gRbWdHQ3d5RWU3Mmc/view?usp=sharing





I will buy USBasp programator is it a good idea?
It's normal that the L-LED is steady on after the USB connection is established. However, after pressing and releasing Reset it should flicker for a second, then go back to on again.

Check https://www.arduino.cc/en/Guide/Troubleshooting#toc1 for reasons why you can't upload.

On http://www.arduino.org/products/boards/4-arduino-boards/arduino-uno I've found:


  The Arduino Uno has a resettable polyfuse that protects your computer's USB ports from shorts and overcurrent. Although most computers provide their own internal protection, the fuse provides an extra layer of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break the connection until the short or overload is removed.


I haven't found out so far, how to read the current values of the fuses.