We have been having problems with our UNO's (a few year old version 1, or 0.00). I've been going through the forums and managed to:
1) download the newest firmware (Arduino-usbserial-uno.hex - this was really tricky to find - or to download! Also using the firmware inside the Arduino software did not update the UNO),
2) download the dfu-updater,
3) set the UNO to DFU mode, which was recognized by the system (os x 10.6.8, more info-usb: Arduino Uno DFU). The two cords from ground to reset pin and a capacitor seemed to do the trick.
4) Use the dfu-updater to do some command-line magic to clear, flash and reset the firmware.
5) Finally unplugging, getting back to UNO.
This works on some of our UNOs, but not all. First I thought the boards were from the same batch, but on closer look the other (working) one looks a bit more greenish-blue, especially on the back. The component layout looks the same (non-SMD, no pins soldered to the reset-area on the top left). But how would I recognize the difference between UNO v.1 and UNO v.2? (MEGA8U2 in these ones, right?, the v3 uses a different chip).
So after updating the firmware the other UNO is working, but the other one still gives the "avrdude: stk500_recv(): programmer is not responding" message. Needless to say, the port, the board and cables should not be the problem since I am comparing them side by side and making sure everything is correct. On the working one, using verbose debugging everything seems to go smoothly, but on the not-working one I don't even get this line:
AVR Part :ATMEGA328P
Both are recognized now in the Apple Menu > System Profiler > More info as Arduino UNOs, Version: 0.01. Yes, I did refresh after plugging a new device in.
So I think this UNO is gone. But perhaps I could write some other Firmware to it? All the interesting ones I found (midi, HID) required a program to be uploaded to Arduino first, and then updating the firmware (some back and forth if I understood correctly). And this I cannot do now. So if there are some useful firmware that can replace the Arduino-usbserial-uno.hex without uploading some program to the board, I'd like to try those out.
Any similar experiences? Is the Leonardo better than the UNO's? We've never had these kind of problems with Duemilanoves.