Is Arduino Nano the smallest Arduino?

I only need about 2 output pins for my project and would like the smallest Arduino as possible. I got a Nano but I wonder if there are even smaller options nowadays? One thing that is important is that it must have Micro-USB for ease of programming.

I googled it and saw the Beetle, but it looks nothing like a typical Arduino board. Not sure about the quality. Advice?



The Attiny85 is just a barebone chip. I need something that I can program using the Arduino IDE via an on-board USB connector.


Attiny85 vusb

No you don’t you program an Arduino to act as a programmer and load your software with that.

I have one, it is very good. It is based on the same processor that is in the Leonardo, but with not so many pins brought out. On the underside there are more pins tracked out if you need them. Quality is fine, better than any cheap Chinese nano I have seen.

I’ve settled on the Arduino Pro Mini.

You need a FTDI board ($3-4) to connect to the USB for programming.


You might like to give some thought to one of these:

I use one to insert an 8 digit random number at the current cursor position on my PC when I press a button; it works like a charm.

I power it via a header-to-microUSB cable I bought via AliExpress.

Hope this helps.

Why is it a requirement to have an onboard USB connector ?

Any other requirements ?

OK if you can say without then needing to kill me, why what for?


Just so long as you keep this just between you and me so not a single other living soul finds out :wink: (just kidding) ...

Two reasons:

  1. I used random numbers for invoice numbers so one particular customer couldn't work out what (high) percentage of all invoices of mine were for them ... and use that to leverage a better rate, and

  2. I use them to generate "search tags" on Google drive. Case in point - I upload footage from my dash cam on my motorbike - I like to be able to quickly locate footage of people doing idiotic things so whenever there's an incident I simply record it in a document of incidents along with one of my random number sequences - and use the same number as part of the file name. That way I can find any incident in a few seconds simply by copy/pasting the number into the search field.

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Using random invoice numbers will cause you no end of grief when it comes to tracking orders by their number alone .
Better to be honest with your customers even at this stage , not a great business strategy to deceive .

The random function in Arduino is not truly random !

They will smell a rat anyway when you send a second invoice with a lower number than the first .
What happens when you start generating numbers you’ve already used ??

If you must , add a constant extra digit to the start to impress /deceive …

Invoice 30XX

Back on topic,
This is the smallest processor board I have with a USB connector. Low cost as well, in the UK they are less than £5.

ATTiny13 or ATTINY85?

It hasn't and it won't; I've been doing it this way for about 5 years now and it works just fine. And it will continue to work just fine.

I'm not deceiving anyone; I really don't think that if my customer got invoice number 28763276 one week and invoice number 95377867 the next week that they would be deceived into thinking that I'd sent 66,614,591 other invoices inbetween.

Which is why I seed it with a random number generated by compositing the least significate bit from multiple analog port reads of a floating input (with time to drift between reads); you can read more about the technique I use here:

Nobody "smelled any rats" because there were no "rats to smell".

First up, the accounting system would tell me. Second up, it's highly unlikely to ever happen (and it would take about 2 seconds to generate another one if it did) because I only send out around 200 invoices a year and an 8 digit number covers 100,000,000 possible numbers - so the chances of getting a duplicate are statistically highly improbable; about a 50% chance every 1/2 a million years.

Again, I'm not trying to impress - or deceiving - anyone. There is ZERO requirement for invoices to have sequential numbers; it is completely my decision as to what numbers I put on my invoices.

Apologies to the OP, but I felt compelled to respond to this.

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Why don't you use Digispark USB Development Board
or its clone with Micro USB

The ATtiny85 module shown above can also be programmed using a usbasp AVR programmer (plugs into usb just the same as a TTL programmer) and using following connections, it will program without the bootloader.
AVR .....ATtiny85
Gnd ...... Gnd
Vcc ........ 5V
MOSI..... P0
MISO..... P1
SCK........ P2
You'll need the board manager to include David A Mellis

Easy just follow instruction here under "Martin" ........

But OP wants to program through micro-USB.
Your link is not working.

If they get any smaller we'll have to start attaching Tiles or Air Tags to keep track of them!

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Can you power the Beetle with a 9V battery?