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Topic: Lost USB Communication (Read 193 times) previous topic - next topic

krgoodwin

My Arduino was working fine all day, as it has for years. I disconnected USB cable, added an Ethernet shield, connected the USB cable back and I could no longer connect via Serial Monitor. I disconnected the Ethernet shield and it worked again. Connected the shield and it went back to no connection. COM3 was in the Device Manager, everything looked like it should work but the IDE was telling my COM3 is not available and Tools/Port menu was greyed out. Did this a couple more times, then thought I would restart the computer with the shield attached. Now I still cant connect in the IDE and have no entry in Device Manager anymore.

The internet tells me its the firmware on the MEGA8U2. Seems odd as before the restart it worked without the shield. In any case Arduino's help page is super useless. The link's broken but FLIP isn't too hard to find. However touching the pins on the header doesn't seem to do anything and there is no option to simply "upload the hex file" as the page suggests. There is also no option for MEGA8U2 or even AT90USB82 as this guy's video shows in FLIP.

Speaking of that guys video, I follow his instructions to get the device into DFU mode, which are different than the other page's. The lights flash but I still get nothing in the Device Manager like he does in the video. Even if I did, FLIP doesn't have AT90USB82 listed as an option for me anyways like it does for him. Maybe it shows up after drivers get installed but I can't do that since it doesn't show up in the Device Manager.

Does anyone have any thoughts on how to get this thing working again before I throw it out?

sterretje

Can't help how to get your board working again.

Your shield might draw too much power. It might also use the Arduino's TX and RX pins, but that would (to my knowledge) not explain why it's not recognised; it might / will interfere with uploads though.
If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.

DrAzzy

Is the bottom of the shield shorting against the metal frame of the USB connector? I've heard that that is sometimes an issue.
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krgoodwin

#3
Jan 14, 2018, 05:38 pm Last Edit: Jan 14, 2018, 05:45 pm by krgoodwin
Your shield might draw too much power. It might also use the Arduino's TX and RX pins, but that would (to my knowledge) not explain why it's not recognised; it might / will interfere with uploads though.
The shield may very well have drawn too much power. It's a clone of the standard Ethernet shield. As far as I knew it should have worked fine off USB power. The shield is supposed to use the ISP communication not TX and RX. The store I bought the shield from said they have never gotten complaints about it...

Is the bottom of the shield shorting against the metal frame of the USB connector? I've heard that that is sometimes an issue.
No, the pins on the shield were long enough that they bottomed out in the headers and there was significant clearance.

I have solved the problem. Below are the steps I took to do so for anyone in the future experiencing this issue and are frustrated with the lack of documentation.

After starting my computer this morning I now have a "Arduino Uno DFU" device in my Device Manager. Seems like either the Arduino or the PC needed a power cycle for it to kick in.

Still not home free yet as apparently the drivers I got with the FLIP install are either not for the Arduino or not for Windows 7. The FLIP version in the video and other tutorials is 3.4.7. I was only able to find a 2.4.6 package for download.

I downloaded dfu programmer 0.7.2 which included the proper drivers. So now I have a AT90USB82 in the Device Manager but FLIP still don't seem to like it.

I abandoned FLIP and with the hex file that comes with Arduino, entered into the command line two lines:

dfu-programmer AT90USB82 erase
dfupprogrammer AT90USB82 flash Arduino-usbserial-uno.hex

Now my COM port is back and the Arduino is functioning like nothing ever happened.

I still don't know how or why the processor crapped out. Still don't know exactly which procedure kicked it into DFU mode. But at least it's working and hopefully this will be useful to someone in the future.

The firmware update page on this site really needs some updating. It's linking websites (ATMEL) that don't exist anymore and software that doesn't work, or at least the version that works isn't hosted anymore. For a problem that seems fairly common and a device that is supposed to be entry level noob friendly this seems like this would be an issue.

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