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Topic: UNO dead, not detected on USB, latest sketch not running (Read 3328 times) previous topic - next topic

ArduTinker

Aug 27, 2011, 08:40 pm Last Edit: Aug 27, 2011, 08:44 pm by ArduTinker Reason: 1
Hi, I'm afraid that I just bricked my Arduino Uno.

I bought it about 10 days ago and tried out several things so far.

I was playing around with unipolar stepper motor, the corresponding lib and the recommended schematic to control it (ULN4004, 2-wire mode) when the Arduino stopped working after I plugged in another motor. I was driving the motor via USB power, parts of the time I also had an additional power supply attached to the Arduino.

It is getting power via USB (power LED on), but is not detected as a USB serial device any more (MacOS X). The last sketch (a simple one to drive a motor back and forth) seems not to be running.

So far I've tried the following:
- Detaching everything except USB from the Arduino
- Rebooting the computer
- Different Computer (Windows)
- Different USB cable
- Different USB hub

So it seems that something is seriously broken.

I do have simple electronics measurement equipment (multimeter, 40 MHz USB oscilloscope), but no possibility to re-flash the boot loader, etc., except if I'd build a parallel programmer. I could also exchange the Atmel 328P, as my local electronics store has them on stock.

Is there anything else I can do, except buying a new Arduino?

Bye, Matthias

CrossRoads

Does anything else work using that same USB port?

"is not detected as a USB serial device any more" infers you took out the 8U2 chip that does the PC interface.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

ArduTinker

#2
Aug 27, 2011, 08:48 pm Last Edit: Aug 27, 2011, 08:50 pm by ArduTinker Reason: 1
Hi,

Quote
Does anything else work using that same USB port?


yes, it does. I've also tried different ports.

Quote
...infers you took out the 8U2 chip that does the PC interface.


Is there anything I can try about this?

And somehow I believe that that's not all, because otherwise the last sketch should still be running, shouldn't it?

Bye, Matthias

CrossRoads

Connect the Rx 8 Tx pins (D0/D1) with '328 removed. Open the IDE's serial monitor.  Your typing should be repeated back, if not the USB interface is gone.
The '328 can work still work even if the USB interface is gone.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

ArduTinker

#4
Aug 28, 2011, 10:32 pm Last Edit: Aug 29, 2011, 04:23 pm by ArduTinker Reason: 1
Hi CrossRoads,

thanks for your time. I'm afraid that it did not work and I'll have to buy a new one.

By the way, the chip below the quartz is getting quite hot, even if the 328 is removed.

Before the Arduino went broke, I noticed something odd: The unipolar stepper control circuit did not work when the Arduino was powered by an external power supply (12V), only when powered via USB. The only difference I could detect was that with USB, the 5V voltage was 4,9... V, with external power supply only 4,7... V. Any ideas what could have caused that, maybe the problem is the power supply on the board?

Bye, Matthias

ArduTinker

Hi,

one Arduino later, I just learned two things:

1. The Arduino seems to require a well-stabilized power supply. It did not work reliably with a simple "wall wart"-style 12 V power supply, but it did with a laboratory power supply.

2. I am quite sure now that I killed the Arduino with a shortcut between Vin (12V) and 5V. Can someone tell me which parts need to be replaced now?

Bye, Matthias

CrossRoads

There's only a couple of parts - the ATMega328, and the AT8MU2.
Hard to do either without a hot air rework station.

If the '328 is a DIP, that is easy.
The other one, if you can get it off, you can wire in one of these as a replacement
http://www.ebay.com/itm/USB-2-0-UART-TTL-6PIN-Module-Serial-Converter-CP2102-/370532286388?pt=PCC_Drives_Storage_Internal&hash=item564571ffb4

Or use it with one of these & assemble yourself a board.
http://www.nkcelectronics.com/arduino-runtime-board-rev-b.html

Or something smaller if you want - I have 50 of these bare boards on order, 27 spoken for so far:
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

retrolefty

1. The Arduino seems to require a well-stabilized power supply. It did not work reliably with a simple "wall wart"-style 12 V power supply, but it did with a laboratory power supply.

Well many many do use a simple unregulated 12vdc wall wart to power their arduino successfully. Your specific one may be different?  

2. I am quite sure now that I killed the Arduino with a shortcut between Vin (12V) and 5V. Can someone tell me which parts need to be replaced now?

That would do it, shorting 12 volts onto the 5 volt bus will take out both the 328 and the 8u2 chips, maybe even the on-board +5vdc regulator chip. I think you will probably be better off just buying a new board, unless you have the tools and experiance with removing and replacing a SMD chip.

Lefty

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