I blew my arduino uno atmel controller.. 'again'

The problem is as follow, i have:
2 NO/NC/common switches (define maximum and minimum position of the motor
1 bluetooth hc05
1 l298n
1 potentiometer
1 temp sensor
1 psu 12v 2.5A
1 motor dc 12v 1A

It's a PID, with the possibility to view it through processing

The problem is that 'something' happens to the 5v line, because the usb/ttl converter dies and the DAC converts analog input start giving erratic value's, the arduino is not programmable after that.

I put a schematic with it it's exactly connected as shown. The only difference is the common of the switches have a 10k resistor between de arduino digital and the common on the switch.

NO is connected to 5v and NC is connected to ground. So when it switches it reads as a HIGH on the digital input which stops the motor. I will include the code later.

There is no smell of burning or components running hot. I just dies in silence.

The motor drive board is being fed from the Vin pin powered through the barrel jack. There is a diode between the two with a rating of 1A.

With two motors running you take 2A which will blow this diode.

Sorry, i forgot to mention, i supply the arduino through the Vin, because of that reason


AS @Grumpy_Mike has explained in your configuration, you are running motor current through the UNO and the protection diode.
The diode is not rated at the current needed to run your motors.
Nor would the pcb tracks.

Suggestion is to supply the motor driver directly to the 12V supply, not the UNO board Vin pin.

If you are worried about reverse connections, fit a separate 5A diode in series with the motor 12V wire.

Tom.... :smiley: :+1: :coffee: :australia:

Thanks for the info ;), but what i dont understand if i would have as an example a motorshield, would the Vin pin connected to the shield? And would this give problem's with an inductive load?

No it would not. There is normally a separate connection for the voltage supply for the motor. Unless of course it was stupidly designed, or limited to say 800mA as the total you could drive with it.

But on this you can just hookup a supply of more then 1A.

I tried another arduino and the same, but i noticed the problem started when connecting the bluetooth module. The strange thing is it works.. i can connect to it, and see through processing the value's and can sent even data. The only thing i noticed that i couldn't upload code through the serial of bluetooth.

COM in/outgoing is set in windows

Sorry but no idea what you mean by this.

If you apply a power supply to the Vin pin then yes you can get more than an amp if you connect the load direct to that pin as well, but that is not what you had before.

I found the culprit in the bluetooth module, the moment i hook the thing up, the analog value's start reading max value around 1023 and the led on pin 13 dimmed up but on a very low luminosty. Even by turning the potentiometer the value's stay the same, onhooked every thing except the potentiometer, still the same.

So the i think the DAC converters get blown all the time

I think at this time you draw YOUR circuit out in a diagram.
Reverse engineer your circuit.
Hand draw it using labels on all pins and components and post an image.

Thanks.. Tom... :smiley: :+1: :coffee: :australia:
PS. Fritzy picture do not cut it when it comes to troubleshooting, draw your circuit.

Sorry that makes no sense at all.
So like Tom asked can we have a real schematic.

I hope the drawing will clarify some. I connected the bluetooth module to Rx and Tx directly, i dont need the usb interface after programming and

i didn't use a level shifter.

You are connecting the potentiometer the wrong way.
The wiper should be connected to analog inputs, the ends to 5V and gnd.

The way you have it you will short the 5V to gnd when you turn the pot to one end.

What NTC do you have that has three terminals?
Please post a link to specs/data.

Can you please post picture(s) of your project so we can see your component layout?

Thanks.. Tom... :smiley: :+1: :coffee: :australia:![circuit|543x500]

The potmeter is connected the right way the drawing is a little of.. sorry for this. I will take a picture of the project when i get home ;).

Thanks for the support.

Not a good start! :roll_eyes:

And powering an Arduino project via "Vin" or the "barrel jack" with 12 V is also a bad start. Get a proper 5 V power supply.

Do you really have the diodes on the motor lines connected to the +5V going to the arduino instead of the +12V supply?


Good catch, that would be putting 12PWM on the 5V supply rail when ever the motor is running.

Tom... :smiley: :+1: :coffee: :australia:

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