Arduino UNO R3 atmega16u2 can't enter DFU mode

Development Tools IDE 1.x
1

Hey everyone,

I have been trying to enter DFU mode on my UNO r3 without success.
After searching for an answer for hours I've decided to ask on here and see if anyone can help me out.

I'm using windows 8.1 on a laptop that has both USB 2 and 3 as well as OSX Yosemite using VMware. I wanted to try all these combinations as well as another pc to see if it made a difference.

As far as I understand it you have to connect the Ground and Reset pins of the headers closest to the USB port when the Arduino is plugged in or while plugging it in. After which the device should disappear from device manager and show as an unknown device or the name with DFU in the title.

This is a photo from another post showing these pins:

There seems to be different ground pins that are usable for this according to multiple posts and sites. Like the following:

800×556 158 KB

If I use the pins in the second method the led titled L flashes three times then pauses and flashes one more time. During this the Arduino disconnects from windows and will only reconnect when these pins are disconnected. It always shows up as Arduino UNO (COM4) though so I'm not sure if this just causes a reset because it behaves the same as if the reset button is pressed.

I have read many posts about this issue and none of the methods or suggestions have helped me at all.
I also read on a thread that the atmega16u2 could be empty on my board in which case they suggested to use an ISP programmer to flash the firmware. I don't happen to have a programmer or a second UNO as you can use that instead. What I do have is a Arduino Due but I'm not sure if I can use that as a programmer for the UNO.

Anyway, I hope someone can help me out with this as it's driving me nuts.
I wanted to include links to the specific threads that I read but I can't seem to find them anymore.

I'm pretty sure that the UNO I have is a genuine one but I will attach photos anyway in case there is a difference with my board.

The 16u2 is titled:
ATMEL
MEGA16U2
1440 PH
4W4604KJ

The other is:
ATMEL
1437
ATMEGA328P-PU

Feel free to ask for any other information that you think would be useful!

Thanks in advance!
RubenA

2

Just an update on my issue above.

I was able to finally enter DFU mode on my UNO.
After a lot of research/searching I was able to flash the atmega16u2 on the UNO using ArduinoISP on my DUE.

This took quite a while because of all the research and searching I had to do regarding ArduinoISP on a DUE.
The voltage difference between the DUE and UNO was also a problem when attempting this.

I also had to run the flashing commands for AVRDUDE using CMD as the Arduino IDE was not working for some reason.

I will post more details about the steps involved in getting this to work tomorrow as I have run out of time today.

I guess my problem was that the atmega16u2 was not flashed during production and that was why I could not enter DFU mode using the traditional methods.

Ruben A

3

That is good news, you are resourceful. I think there is somebody out there producing boards without programming the ATmega16U2. There have been several topics on the forum where people have had to either return the boards or program the ATmega16U2 on brand new boards. If the board came this way, I recommend contacting the seller to let them know they are shipping boards with unprogrammed ATmega16U2's.

Your board is a counterfeit: https://www.arduino.cc/en/Products/Counterfeit