Would like help figuring out what I've done to my Uno R3

Hello!

I've had my Uno R3 for a couple of weeks. Everything was going fine and then I think I accidentally sent 12V into the wrong pin(s).

So I've spent a few hours trying to figure out just which part is broken and whether the board is salvageable. It's pretty clear to me that I need help from this beneficent forum.

BTW, first post

Some data points:

• When I plug the board in to my mac, the usb device appears
• The green "on" led comes on. The orange L1 led comes on (the one on digital out 13).
• The reset button has no effect
• The orange led doesn't behave the way it used to. On power-on it stays steady rather than flashing for a little while before remaining steady.
• I can't upload sketches. I get: "avrdude: stk500_recv(): programmer is not responding"
• I can use the serial monitor to send text to the Uno and the RX light flashes but the TX light doesn't flash
• I tried the loopback test by connecting pins 0 and 1 (TX & RX) and RESET and GND and powering on the Uno. The text comes back to me as expected. So it looks like the 16u2 is working
• Just to be sure, I put the 16u2 into DFU mode and reflashed it with dfu-programmer (which I had to patch to support the atmega16u2) and that went fine
• On the chance that it's the atmega328p that's not working, I bought a replacement. I couldn't get a atmega328p right away (I'll have to order one online) but I did get an atmega8 which I inserted (the right way around).

I can't burn the bootloader. I've tried "Arduino Uno" and "Arduino NG or older w/ATmega8" but they both give the same result:

/Users/jeremy/Downloads/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/avrdude -C/Users/jeremy/Downloads/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega8 -cstk500v1 -P/dev/tty.usbmodemfa131 -e -Ulock:w:0x3F:m -Uhfuse:w:0xca:m -Ulfuse:w:0xdf:m

avrdude: Version 5.11, compiled on Sep 2 2011 at 18:52:52
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2009 Joerg Wunsch

System wide configuration file is "/Users/jeremy/Downloads/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"
User configuration file is "/Users/jeremy/.avrduderc"
User configuration file does not exist or is not a regular file, skipping

Using Port : /dev/tty.usbmodemfa131
Using Programmer : stk500v1
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding

avrdude done. Thank you.

"/dev/tty.usbmodemfa131" is the correct device and I can see the RX light flash. The TX light doesn't flash.

I'm out of ideas. Except getting another board!

Any thoughts?

Cheers,
Jeremy

By the way, I'm in Sydney Australia so, while I'm pretty motivated to fix my Uno (or at least diagnose it), I may not reply right away if it's the middle of the night here

Is five volts present at the 5V pin?

Is 3.3 volts present at the 3.3V pin?

I can't burn the bootloader.

You have to have a programmer or another Arduino board acting as a programmer to burn a bootloader.

For what you've described, the board itself is OK but the processor has either lost the bootloader or has been damaged. The next step is to get a replacement processor with a bootloader already installed.

Is five volts present at the 5V pin?

Is 3.3 volts present at the 3.3V pin?

Yes to both of those. Which I assume means the voltage regulator is still okay.

You have to have a programmer or another Arduino board acting as a programmer to burn a bootloader.

For what you've described, the board itself is OK but the processor has either lost the bootloader or has been damaged. The next step is to get a replacement processor with a bootloader already installed.

Oh, that makes sense. I'll go ahead and do that. Thanks for the quick response!

Cheers,
Jeremy

jezparov:
Except getting another board!

Another board isn't the end of the world. I regularly use two boards, eg. to send from one to the other.

Also if you have a second board you can set it up to program the bootloader on the first board, once you get the replacement chip. From the sound of it you zapped the processor with your 12V.

The replacement chips are only about $5 so you have probably only wasted that.

Another board isn't the end of the world. I regularly use two boards, eg. to send from one to the other.

Also if you have a second board you can set it up to program the bootloader on the first board, once you get the replacement chip. From the sound of it you zapped the processor with your 12V.

Yeah, seems like that would be handy. (Like now for example!)

The replacement chips are only about $5 so you have probably only wasted that.

Yep, that's what I'm hoping!

Robotics Australia has them with the bootloader for $5 but postage is $6.95.

Jaycar has the Uno-compatible "Eleven" for $39.95, so it might be worth the extra $28 to get the board in addition to the ATmega328p

Cheers and thanks for the reply!

The two Arduino scenario does play nicely on the bench since troubleshooting quickly is best done with two identical boards. As far as the "preloaded bootloader", I have one that I keep nice and healthy in the parts drawer. All the rest are naked 328s that I flash... at about 2::1 pricing, the naked chips are quiet nice especially if you are building your own hardware for projects and do not wish to sacrifice a nice UNO.

• Ray

A new 328 with a bootloader pre-installed just arrived in the post from Australian Robotics and all is well with my Uno.

In the long term, I'll get another board but for now I'm happy that I'm back up and running.

Thanks all for your help!