Reset 8u2 on Arduino Mega 2560

arduino

Another question along with this one.

The guide I've been following says that after you reset the 8u2 by connecting the two pins shown below, the board should be undetectable by the Arduino IDE. I have successfully done so, but the board is still using COM22 as an Arduino Mega in the device manager. This other guide I found shows the board becoming a LibUSB-Win32 device. Anyone know what's going on?

Pins to connect

Best Answer

I have confirmed that, on my UNO R2, if I bridge the two connections shown briefly, the 8U2 resets and enters DFU mode. Instantly, the logs on my Linux system that it is connected to show that the ACM device (what would be COM22 for you) has been removed, and replaced with a generic USB device. The dfu-programmer command can then communicate with it fine.

The bridging of the connection should be done:

  1. while the Arduino is connected to the computer and powered up,
  2. briefly, with a bit of wire, resistor leg, screwdriver, tweezers, etc - whatever you have to hand.

Removing power from the Arduino and re-connecting it returns it back to normal operation.

  • Incidentally, the UNO R2 has that block of 6 pins populated with a header - makes it easier...
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