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I have an arduino that I programmed a PWM signal on pin 5. When I power the arduino with 12v or USB5v, pin 5 has the PWM signal. Iam checking it with a oscilloscope. Oddly enough the arduino is not recognisable to a windows PC or MAC, the device never shows up on the usb. The LED on the device seem to give all the right signals. The Green ON LED is on. And the L LED is also on. The program is not using serial so the RX and TX are not on.

When I try another Arduino it works fine.

What could I have broke? I am guessing the ATmega328 is fine?

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    Try reflashing the ATMega16u2 that does the usb-to-serial. Try it using the DFU option. If that fails use another arduino to reflash using ISP (using the ISP header right near the chip in question. If that also fails most the atmega16u2 is probably broken the board is beyond economical repair
    – Gerben
    Commented Oct 6, 2015 at 20:12
  • Tried that, with no luck. Yeah I am not trying to fix for $$ reason, just trying to understand what went wrong.
    – Vitaly Babiy
    Commented Oct 7, 2015 at 1:09
  • with no luck. Could you expand on that. Were you unable to update the firmware, or did it not have any effect.
    – Gerben
    Commented Oct 7, 2015 at 8:23
  • I was not able to use DFU option because the UNO is not detected by the pc or mac. I tried the ISP option and burned the bootloader, but it still is not detected by the computers.
    – Vitaly Babiy
    Commented Oct 7, 2015 at 12:03
  • Did the ISP programmer successfully verify the flashed rom?
    – Avamander
    Commented Feb 3, 2016 at 19:20

1 Answer 1

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Just a guess, if anything else work fine, my (first) guess would be the serial to usb adapter. I damaged one a while ago on a breadboard but also dont know how. But it could also be almost everything else. The pwm sketch, in which language is it written and burned? Does the Atmega have a bootloader on it?

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  • The sketch was really simple, just doing a analogWrite(5, 100);
    – Vitaly Babiy
    Commented Oct 6, 2015 at 16:44
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    And how have you load it onto the arduino?
    – BrainWorx
    Commented Oct 6, 2015 at 16:47
  • Using the arduino IDE
    – Vitaly Babiy
    Commented Oct 6, 2015 at 16:48
  • have you seen any error message inside the status window? would be nice if you tell a bit more..
    – BrainWorx
    Commented Oct 6, 2015 at 16:52
  • The only error I see is the it can't find the usbmodem because the computer is not seeing the uno
    – Vitaly Babiy
    Commented Oct 6, 2015 at 16:52

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