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I have an Arduino Mega 2560 which was working just fine a few days ago. I've just been working with it and now it's not being recognised by any computer, not even as an un-recognised device.

The power LED lights up and the L led near the USB port flashes briefly, but apart from that nothing much happens. I think it runs the code that was on it before it stopped working too.

The question is, have I fried something on it (like the USB controller) and can it be repaired, or is there something else I need to try to fix it?

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  • \$\begingroup\$ On Linux you can check with lsusb or dmesg | tail if your device registers with the operating system. In Windows ... Best guess is the device manager under control panel. \$\endgroup\$ – jippie Apr 5 '12 at 20:07
  • \$\begingroup\$ The circuit diagram looks a bit crowded, but it isn't too complex. Did you check it? arduino.cc/en/uploads/Main/arduino-mega2560_R3-schematic.pdf \$\endgroup\$ – jippie Apr 5 '12 at 20:11
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    \$\begingroup\$ Apparently you're very impatient: last time you visited here was 9 minutes after you asked the question. \$\endgroup\$ – stevenvh Jul 9 '12 at 14:39
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Even if the original USB-serial is bad (and can't simply be reflashed), if the main processor seems good you may have the option of communicating with it using an outboard USB-serial converter or level shifter (if you can still find a real serial port). For a plain arduino it would be barely worth it, for a mega with its substantially higher price it could well be worth the trouble.

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In the Arduino IDE does any serial port appear under Tools => Serial Port after you've plugged it in and then not appear after you've unplugged it? If so yes you can be fairly confident your USB-to-Serial chip has been damaged in some way.

Try all the usual debugging/isolation approaches before you conclude this (i.e. try with a different USB cable, try with a different computer, etc).

I also haven't used the Arduino Mega before, but I've heard that there are problems with the bootloader for it. I'd browse the Arduino Developer List archives if you suspect this is the problem (but I doubt it based on your description of the symptoms).

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I'm having the same problem, and by the time of this post I have not solved it. The problem seems to be the USB-serial converter chip being washed out, meaning it's firmware is no longer working correctly. Depending on your board this could be an ATmega 16u2 or (like in my case) 8u2. On the board you'll see two ICSP headers. One near the big chip, which is for loading the bootloader on the 2560 while the other is near the USB port, this is the one used for programming the 16u2/8u2. You'll need an STK500 programmer, the Atmel's Flip software (on windows) and the firmware .hex file provided on your arduino-1.0.x/hardware/arduino/firmwares/arduino-usbserial/ folder. Also you can use another arduino, loaded with the ArduinoISP sketch instead of the STK500 and the cmd prompt line

avrdude.exe -C [pathToArduinoFolder]\arduino-1.0.1\hardware\tools\avr\etc\avrdude.conf -c arduino -p at90usb82 -P [COM_Port_where_arduinoISP_is_connected] -F -U flash:w: [pathToArduinoFolder]\arduino-1.0.1\hardware\arduino\firmwares\arduino-usbserial\arduino-usbserial-mega.hex

This is as far as I have gotten, the program runs fine but the 8u2 I'm trying to program seems to be not responding. Hope this helps, if you fix your problem with the second approach let me know.

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