My Arduino Uno board is different

Hi to all,

I suppose I don´t have a hardware problem but my Arduino Uno board is different from the one on the site and several other sites that sell it. Some components are missing but they don´t seem to have fell off.

My Arduino Uno board:

Arduino One board on the official site:

Does someone know why is it different? Thank you.

Regards,
Luis Sismeiro

The big question is "Does it work?"

It could be that the crystals are double footprinted to allow for alternative components in case of component shortage. My UNO is like the bottom one with a crystal on the USB chip and a resonator on the main processor.

@PaulS: It works rather well. It's my first Arduino board and all the example sketches from several tutorials work and my own sketches work without problems.

Is this a new revision of the Arduino board? I bought it last week from a seller here in Portugal and listed in the Arduino site.

I wouldn't worry about it.

I highly doubt it is any kind of clone (especially as the silkscreen is exactly the same and that's not avaliable anywhere).

Boards often get small changes and new revisions.

If it works fine then I say go with it. ;)

Picture of the bottom of yours for comparison?

@biocow: From what I can see, I don't find any difference between the bottom of my board and the image on the site, but I am not an expert.

Your board has 16MHz "resonators" for both the main AVR and the USB chip, while the early Unos had a resonator for the main AVR and a "real crystal" for the USB chip. The boards are laid out to accept either one in either position. I dunno why they switched (actually, I dunno why the original Unos had one of each; that was weirder than your board's configuration.)

I think some of it has to do with concerns about emissions for FCC / CE testing, etc.

Just bought an Arduino Uno from a local supplier here in Torino, Italy. 30 Km from where they build the Arduino.

My board looks exactly like your's Luis (no crystal) and I'm pretty sure that mine isn't a fake.

I wonder if this could be related to cost savings.... While the cost difference between a crystal and a resonator is quite small but it could add up to be quite significant consider the number of boards they build.

probably a cost savings thing. In addition to being slightly cheaper, resonators eliminate the need for external capacitors, and are SMT parts that won't require hand assembly after the pick&Place machine is done.

and are SMT parts that won't require hand assembly after the pick&Place machine is done.

Well it would be just as easy to get an SMT crystal.

So, what are the drawbacks of having a resonator instead of a real crystal?

It is not as accurate, that is a crystal can be closer to the frequency marked on it. It is deemed that a resonator is "close enough". This affects timing critical stuff like the serial baud rate.

This affects timing critical stuff like the serial baud rate.

Well it’s not as if anyone seems to use anything but 9600 or 19200 which aren’t exactly perfect at 16MHz anyway ;D

Fabio Varesano said: Just bought an Arduino Uno from a local supplier here in Torino, Italy. 30 Km from where they build the Arduino.

My board looks exactly like your's Luis (no crystal) and I'm pretty sure that mine isn't a fake.

I never though it could be a fake Arduino since it was bought in a "official" seller mentioned on the arduino.cc page, just a different board revision.

The strange thing is that on the official arduino.cc page doesn't mention anything about this change and I think it should be public like everything else is.