Very small microcontroller Arduino rogrammable? Answered


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Hey all!

I really need some help! Ok, so I want to make a very small circuit and put it in my watch, but I don't have any microcontollers small enough tor with enough pins. I want around 16-20 I/O pins but I want it to be in a very small package. Like the flat square ones with 10 pins, or the long thin rectangular ones. It also has to be able to be programmed using my Arduino.

Several suggestions and help on how to find my own would be a great help!



Getting a µC in a very small package is not a problem, for example, see page 637 of the ATmega µC. 32 pins and only 5x5mm small.

The question is: Can you handle a device that small? The pad pitch is 0.5mm.

You can et almost any popular µC in very small packages. In fact, some interesting devices are only made in packages that are too small to be handleable by hobbyists.

Yeah but not that small. I found something like this, that may work.


Its small enough to fit in my project, has enough pins but big enough so that I can solder it to a PCB.


Yep, that looks reasonable for a hobby project.

But hey, you said 'very small' - I gave you small! :-) The smallest µC I ever saw was 2x2mm and had 16 ball grid contacts on the bottom. Was not allowed to use it in a design - we couldn't find someone to manufacture the PCB reliably and cost effectively.

The web sites of the manufacturers have quite good selectors like here.
To find the dimensions of the packages check the data sheets. Those data sheets are an invaluable (and the most definitive) source of anything you want to know about the devices.

After a bunch of searching I decided to try the Attiny2313 in the smaller package, the same as shown in the picture (I forgot the actually package name). Since I already have the bigger 2313 I figured it would be easy for me to program it.

> Since I already have the bigger 2313 I figured it would be easy for me to program it.

Yes. The function is the same regardless of the package (99.99% of the time, sigh..). That way you can test your design and code on a breadboard with the bigger IC and design a PCB for the slimmed down version.

Good Luck and post an Instructable when you're done.

Alrighty thanks! Okaydokey I might, it if amounts to anything!

You can get the same atmega as on But it is not an easy part to solder. Assuming you already have an Arduino Uno there is this instructable on programming the device Which uses an adaptor.

You might also be able to find a smaller device on this list but they might not have the same features (and the page warns that they are not well documented)