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Topic: Question about loop back test (Read 322 times) previous topic - next topic

marcovaldor

Hey,
When i type data in the serial monitor I see only the RX LED blink but not the TX LED
Do you have any idea what the problem could be ??
i would appreciate any help

CrossRoads

You have D0 and D1 connected, with Reset grounded?
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.

marcovaldor

yes the D0 and the D1 are connected together and the Reset pin is connected to the ground

CrossRoads

Did you try changing the USB cable? They are flexible wire & do break occasionally.

Does it do the same if you remove the 328P chip from the board (on the Uno?)?

Do any chips on the board feel warm?

May come down to the USB/Serial chip got zapped somehow.
You can try reloading it.
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.

marcovaldor

Yes about the cip getting warm
My board is an Arduino Rev3 and the chip right next to the TX and RX LEDs gets really warm .

CrossRoads

It's dead then. It should not be warm at all.
The only thing that should feel at all warm is the 5V regulator.
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.

marcovaldor

I changed the USB cable and yet nothing changed
I also tried the same without the 328p chip and it's the same result

CrossRoads

Dead 16U2 then. Unless you have SMD replacement capability, you are out of luck.
You should be able to use an FTDI Basic and connect to +5, Gnd, DTR thru a 0.1uF cap to Reset, and Tx/Rx connected to D0/D1 (or D1/D0) and get serial comm's back that way.
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.

marcovaldor

Then you mean that the arduino is dead?
and what solutions do you think would work ? Could you plz use more simple words , I'm new in arduino .

CrossRoads

Well, it appears the USB/Serial interface chip is dead, the small square one. I don't know about the Atmega328P, the large DIP part.
You can get a bootloaded '328 and an FTDI Basic
https://www.sparkfun.com/products/10524
https://www.sparkfun.com/products/9716

Replace the chip, connect the FTDI Basic as  I discussed earlier, and see if that will get you back in business.
Do you have a voltmeter? You could also check to if 5V and 3.3V are still okay on the board, or if you managed to take out the regulators also. In which case, get a new board and be more careful next time.

This place often has slightly older hardware that will do just fine, such as
http://www.nkcelectronics.com/arduino-duemilanove.html
I still use my Duemilanove for checking out stuff, and I use FTDI chips for my '328P & '1284P designs.
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.

marcovaldor

Do you know what did i do wrong ? So i i'll be careful next time

CrossRoads

Shorted something to something, I don't what you had going on.
The 2-3 chips I zapped on promini's all got brushed with a 12V supply line, killed 'm nice & quick!
My boards use FTDI chip, never had one of those die.
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.

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