Got an Arduino 2009 but where is the RESET-EN ?

I have read this page about the Arduinos Auto-Reset feature:
I can see the RESET-EN line on the image next to the usb port.

But now, looking and the Arduino I received today there is none! It is the Arduino 2009 with the ATmega328 (at least it is written on it :slight_smile: )

But the missing RESET-EN which I cannot spot anywhere seems to be quite annoying.

Were there different board revisions and I got an old one?

The RESET-EN is a solder pad on the underside of the board. You use it to re connect the auto reset circuit if you have cut the link round it.

Is there an image of that? I double checked the underside of the Arduino and nothing to resolder or to cut there

Sorry it is on the top of the board just behind the USB socket labelled RESET-EN.
There is a photo of it here:-

is your board different?

As I mentioned in my first post I have compared it already with the image and there is no such pin next to the USB socket.
I have contacted my supplier and he told me, that his older version have this RESET-EN but are now shipped without it.

They probably decided to ditch the solder pads for RESET-EN, most people love the auto-reset feature, so they just leave it like that permanently. I think my new Duemilanove is missing it too.

As i searched this forum there were some other topics concerning boards before the RESET-EN. there was another way to disable that. Is this gone too? And if not, where is it? :slight_smile:

There is a trace you can cut to disable auto reset, though I'm not sure where it is on the newer boards. I'll have a look at the schematic and post back if/when I find it.

some other topics concerning boards before the RESET-EN.

Pretty picture :

You cut the little track between the solder pads to disable it, you solder across the pads when you realise losing the auto reset due to cutting the track is a pain......... :smiley:

"Mature Duemilanove" the new ones apparently don't have it :frowning:

As you stated by yourself "mature" version of it does definitively not have them there

Never let it be said that the latest version of something is the best..... :frowning:

Looks like they found a cheaper way of doing the auto power switching as well.

Heh heh- that little teeny component looks kinds funny, where they didn’t bother to get rid of the old soldering points.

Now that is interesting. Removing a feature that doesn't add to manufacturing costs.

Seeeduino here I come.

Now that is interesting. Removing a feature that doesn't add to manufacturing costs.

I dunno, think about all that solder sitting on the pads.......

I read somewhere that someone disabled the auto reset by desoldering the .1uF capacitor in the reset circuit and theres a dodge with sticking a 100 ohm resistor between 5v and the reset pin to keep the pin high by brute force despite the best efforts of the auto reset to drag it low.

True it might cost the factory some more but it isn't going to charge the customer any more. :wink:


About 1 1/2 years ago I was complaining heavily about auto-rest. It's a perfect thing while developing, but once done it's a curse. I used an arduino diecimila board in a lab device. I needed a working device quickly, no time for custom boards. Rapid prototyping :wink: Finally I chose to desolder the SMD cap. Using a strong pull-up just by sticking a through hole resistor into the headers is a no-go in the real world. Things tend to come loose. Bare metal wires floating around inside an electronics device... the joy!

Maybe the reset-en pads fell victim to a new and secret EU regulation.

"Removal of apparently useless soler pads."

Is it just me or do I smell a fake, where did you guys buy from?


Nahh, this is a fake :

The old Duemilanove picture I posted is a real one, bought from SK Pang, an official dealer linked from the buy page on the Arduino homepage. The picture of the new one is lifted off the same site.

The one above is one I bought off Ebay at around half the cost of a real one.

Ahh ok, I just wondered why they would put a sticker instead of made in italy and why they would change the design. I suppose mainly the RESET-EN just caused confusion or issues.