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Topic: Nano getting pretty hot (Read 3837 times) previous topic - next topic

rva1945

I'm powering it with regulated +5V (coming from the L298n, powered with 7.4V) into pin27. It reads two RC channels and sends PWM to the L298n.

It gets really hot to the touch.

"The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source."

But in the UNO reference it says:

"Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it."

Does it apply to the Nano as well?

DrAzzy

The L298n does not provide a regulated +5v... unless it's on a board that has other parts on it. Where are you getting the +5v from? Are you sure you're not putting 7.4v into the 5v pin? Posting the schematic would be a good thing to do.

If you notice it getting hot again, what part is it getting hot? That is a *huge* clue as to what's going on - but as something is clearly very wrong, I don't avocate connecting it back up just to check this.


The Uno and Nano use different regulators and different circuits, it is not surprising that they have different behavior, and the documentation reflects that.
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rva1945

I'm using the L298n that comes mounted on a board and it provides +5V (provided there is a jumper shorting two specific pins, and there it is).

The Nano is so small that it is hard to tell where the heat comes from, but it gets hot not far from the built-in LED.

DrAzzy

I'm using the L298n that comes mounted on a board and it provides +5V (provided there is a jumper shorting two specific pins, and there it is).

The Nano is so small that it is hard to tell where the heat comes from, but it gets hot not far from the built-in LED.
Is it actually connected to pin 27? Did you measure what it's putting on pin 27 and confirm that it's actually 5v?

Just touch the board while it's hot and then you can feel what part is hot ;-)
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

jack wp

#4
Sep 25, 2015, 07:47 pm Last Edit: Sep 25, 2015, 07:56 pm by jack wp
You mention pin 27, pin 30, on the nano. My nano does not show those numbers, rather labels.

1. What are the labels of the pins you are using?

2. Did the nano just now start getting hot, after several days of being cool? What has changed?

3. How hot is it? warm, or to hot to hold you finger against for 20 seconds?

Boardburner2

#5
Sep 25, 2015, 08:37 pm Last Edit: Sep 25, 2015, 08:40 pm by Boardburner2
from memory 27 is a 5 v OUTPUT from the nanos regulator derved from vin.

Its connected on board to a resistor and led.

That was an official nano though.

Clones i have had , some had diferent pinouts

Boardburner2

#6
Sep 25, 2015, 08:46 pm Last Edit: Sep 25, 2015, 08:48 pm by Boardburner2
But in the UNO reference it says:

"Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it."

Does it apply to the Nano as well?

NO

Nano can be powered from 5 v but not 3.3 according to the blurb.

Ill have a look at one of mine later.

Boardburner2

OK

You need to check the 5v coming off the L298n.

A multimeter may not be good enough for this , you may need a scope.

I had similar problems.

Safest way is to power the nano separately using the 7.4v vin and onboard regulator.

I do not know what driver board you are using but i would not trust the 5 v derived from them espescialy the cheap clones.

rva1945

OK

You need to check the 5v coming off the L298n.

A multimeter may not be good enough for this , you may need a scope.

I had similar problems.

Safest way is to power the nano separately using the 7.4v vin and onboard regulator.

I do not know what driver board you are using but i would not trust the 5 v derived from them espescialy the cheap clones.
Now I'm powering the board with 7.4V using the Vin pin and it works ok, no heat.

Boardburner2

i had the same , i suspect the 5v has a high frequency as imposed on it, that happens with regulators often when there is insufficient decoupling.

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