With the possible exception of it's 5V sibling, this is my favorite Arduino board. It's small, it's inexpensive, and it does everything one would expect of an Arduino.

So removing the solder blob allows you to run the board off a 3.7V lipo. from full charge(4.2V) to discharge (~3.2V) the microcontroller runs its 8MHz quite happily with no complaints. Does really well in deep sleep modes as well.

The biggest problem with Sparkfun boards is, the AREF missing!!! So don't buy it if you want to scale the sensor readings or to improve the resolution of your measurement.

This is perfect if you want to embed an Arduino into a small project. The 3.3v version is awesome as you can directly connect to things like the small WiFi and nRF24 radio boards that are native 3.3v chips - no need for the Sparkfun 5-3.3v converter board.

Make sure you pick up a FTDI 3.3v logic board or cable. The 5v one you probably have lying around won't do you any good with this board.

Really great product. Reasonable cost, documentation sufficient, and great compatibility with Arduino family. Low power consumption, too less than 10ma - that along with the small size and easy hook-up (flexible use of header pins if desired) makes this my go-to Arduino platform.

I really like this and the 5V version. For many projects I prefer them to the UNO. My only beef and the reason for the loss of a star is the fact that pins A4 and A5 are not on the outside of the board and worse, they are offset. So for I2C you have to run wire or build your own board. Not the worst thing ever, but for a tiny bit bigger of a footprint, I personally would have preferred those pins on the outside.

Some of our local amateur radio folks (aka Hams) are supporting a climate change class taught at Williams College. Last year the class launched a balloon that reached 30K feet and we received telemetry data from the balloon. This year we plan to design a more capable payload for the balloon. The light weight, low cost, low power requirements, and availability of software make this product a great choice for generating telemetry data.

I'm using this as an ADC to convert an analog pot into a digital value which is then input into a Raspberry Pi. I had a 9V battery in my project case, so I tried powering this board up using the 9V line on the RAW pin. The product description for this board says the max voltage on RAW is 12V (and the schematic says 16V), but as soon as I connected 9V to RAW, there was a loud "POP" and the bitter taste of disappointment (and melted plastic) in the air. Happily, it was only the regulator IC which blew, and I'm able to power and use the rest of the board using the 3.3V pin on the Raspberry Pi driving the Vcc line on the FTDI header.

Another great SparkFun product, but I still wonder what happened with the voltage regulator. Anyone had a similar experience?

I built my wife a birthday card using this board and some red LEDs. The Pro Mini is the perfect size to hide in a piece of cardboard along with all the wiring and a coin battery. She loved the card.. I constantly look for opportunities to use one of these little guys.. Great product!

This low-voltage arduino can fit every tiny, cableless proyect you can imagine!

I'm currently hacking a PS2 remote controller, in order to use it to drive a RC DIY quadcopter. I emptied the controller, because I found the electronic inside very ugly, and wanted to make all the logic of the controller on my own. I like using Atmel microcontrolers, but I don't have the skills to solder CMS ones: indeed, any DIP-24 package don't fit in the controller. Then, the Pro Mini was the perfect board: it's tiny enough to fit in, and there's no need to CMS solder.

I seem to be collecting microcontroller boards and these are my newest acquisition.

I've used one of these very successfully in a micro/macrophotography stacking rig.

I power mine with 12V or 9V to the RAW pin. No smoke. If there is smoke, something is wrong with your unit or wiring. I always use these with external reverse polarity protection diodes (Schottky) or even MOSFETs. It's easier than you might think to wire things up backwards.

I am a bit perplexed, however, by the location of those four analogue input pins. I guess it makes the board a bit shorter by putting them there, but I'd rather a board that's 5mm longer with those pins placed in-line with the others, two per side.

Another thing to note is that the silk-screening for the TX and RX pins is quite confusing unless you consult the ATMega328 pinout. Arduino UNO, for example, labels their pins TX

0. Letting you know that TX (out) is pin 1, and RX (in) is pin 0. On this board, however, the pin numbers are missing - but to a casual observer, it may not appear that way. Instead, the letters I (in) and O (out) appear, which are easy to confuse with pin numbers. RXI is in fact pin 0, and TXO is in fact pin 1. So beware of that, if you plan to actually use those for something other than serial.

I bought 3/3V and 5 V versions of this and got an immediate download and run. Then they stopped taking downloads and it took 2 days to figure out what it was. In my circuit I was using one of the BT boards (Bluetooth) hooked up to the RX and TX pins. With that connected it will not program. Pull one of the two lines and it programs fine. It's a little irritating but it works and the mini pro is the exact right size and does a great job. The only other thing I can say is that you can't easily hook A4 and A5 to your breadboard if you want to use I2C. You have to solder wires in to A4 and A5 and plug the rest into your breadboard then plug the wires from A4 and A5 into your breadboard. A little irritating but if they were outside then the board would be bigger and it would not fit what I need. Overall I am happy with the mini pros I bought.

I've basically abandoned all Arduino models except this and the Moteino (which is basically a Pro Mini with a radio). I haven't done a project that needed a larger processor or more IO, and for $10, you can make a lot of really cool stuff!

This is a great way to get an MCU into a tiny project based on the easy-to-use Arduino platform. It's very powerful and has the same numnber of i/o pads as the big boards. Getting the program on is a bit tricky, but not too terrible once you have the right set-up.

I really like it. It is the best Arduino board for the small size projects. I recommend this product.

I was spending a lot of time trying to figure out why I couldn't get the Serial1 port to work as it kept screwing up and hanging the Serial data also. I finally looked at the specs and noticed that it has only one UART which is the same as the FTDI port. Actually it doesn't make sense to me. Why would there be wasted RX and TX when they are the same as the RX and TX on the FTDI?

The Pro Mini either in 3V or 5V is my goto Arduino when I don't need the traditional form factor for shields. They are just the thing for building into zombie costumes or tiny robots. These Sparkfun Pro Minis and well made and well supported.

I still could not believe the low current it takes in power down mode. (I hope I use the board correctly to measure the ultra low power down mode current) It is ~200 nA with out the power LED. I have seen others do many changes to the board to get 4.5uA, but just removing only the LED I was able to get it down to ~200NA. It is probably due to MIC5205 Vreg the board. Great Product, love it.

Yes, there's some additional educational overhead because it has less onboard, so this shouldn't be your first arduino. But! It's tiny and uses less power (good for batteries), and fits into wee little projects. This is my go-to device for my embedded systems projects, though I tend toward the simple, so I'm not driving huge light arrays or anything requiring a lot of computational horsepower. I mostly do small art projects or simple detectors. For those, this thing is way more than enough functionality.

This is the perfect little device, great for miniaturizing your projects. It did take me a while to figure out how to program (if programming with an Uno, for instance, you have to remove the ATmega).

Easy to get up and running with these guys, sufficient memory, compatible with a ton of 3.3V devices without the need for level shifting...same reasons everyone else loves them...and they aren't expensive at all...

The Pro Mini is a powerful tool in an incredibly small footprint. It took me a bit to get going with it but there really are no great mysteries to solve. Just carefully follow the "Getting Started Tutorial" and you'll be fine, even if you're a newbie like me. For the price this little device can't be beat!

The Arduino Pro Mini is a very powerful Arduino with lots of features and I/O in a very small package. If you need an Arduino that is physically small or has to run on batteries/low power this is a great choice. This comes in a 5v and 3.3v version, as well as an 8 or 16 MHz option.

One typical usage might be a remote sensor that needs to report data (say temperature or weight) occasionally. The Pro Mini may wake occasionally from h/w powerdown, power up a radio, report the data and then powerdown again. Depending on the factors you might be able to run a year or more on AA batteries.

The Pro Mini comes without headers (you need to add your own) and without a USB connector, so to program it you will need Sparkfun's serial adapter for that. Although it's small it does come with a voltage regulator that can feed peripherals as well as a handy reset button.

Note for ultra low power applications there are many tricks you can find online such as removing the power LED as well as the voltage regulator (assuming you don't need these). Removing one or both of these can have substantial impact on battery life.

Overall it's a great Arduino in a tiny package!

If you need to reduce the size or power of your project, graduate from the Arduino Pro to this board. Possible to power the MCU directly bypassing the on-board regulator if low power is the goal. I wish the LED wasn't on an SPI pin, but that's the same with the larger board too.

Perfect for my various embedded projects, and at amazingly low cost.

i find that the "Sketch" programming approach used by the Arduino folks is great for most applications, but that the ability to embed lower-level code in the applications is also helpful for specialized applications, and, if necessary, to reduce application footprint and save flash space.

The flash capacity of this device (32 KB) is pretty good and having purchased a few of these from Sparkfun, the quality is excellent. I have never received a DOA device.

My current project is using this device and Sparkfun's microSD level-shifting breakout to add an insane amount of storage (like 64GB) to an early 1980s industrial control Z80-based system that has just 16K RAM on board. Weird but fun. I have the hardware working and am developing the communication protocol and device driver routines.

I have also used this device with environmental sensors in a musical training application, where the device and sensors are embedded -within- a medieval instrument to provide wireless, real time feedback to the musician to help him/her improve their playing. Another "weird but fun" thing.

Versatile, I have used both the 3.3V and 5V versions for projects ranging from replacing a Dan Foss fan controller in diesel motorhomes to solar control to smart on/off switch functions in motorhomes.

Easy to program and very reliable, and cheap, what more could anyone ask?

Using it to miniaturize an Uno/ESP8266 design. Great partnership!

We apply it in academic experiment with Smart Sensors.

I'll give these a "5". With 4 smallish projects planned, these were "on sale" so I snatched up 5 (but two were the 5 volt version). Been using these for a few years, and they work better for my projects than an official size Arduino.

Minimal soldering easy programming multitude of great library's.

I use it for almost my project, I cannot imagine how I could do all I do without it. Its key-feature is the size. You can put it almost everywhere.

What is in my dreams? To have the Pro Mini with a larger built-in RAM. Sometimes 32K of flash memory can be a limit.

This is a great, affordable breakout board for my home automation and sensor project. It's very easy to breadboard or place into a PCB of my own making or even stripboarding. It's very easy to program and has more power than I need, I particularly like the lower voltage requirements over the 5.0 volt board. The fact that I bought them on sale for half price makes them particularly attractive.

I recently used the Arduino Pro Mini in a prototype because I needed the full power of the Arduino, but in a smaller form. The Mini has been great and did everything I needed. Specifically, I needed to use 10 digital pins and 1 analog pin.

I highly recommend reading the awesome tutorial in the documents section. This was my first time using the board and I ran into the following gotchas.

• To upload code, you need the FTDI Basic Breakout Board. See the tutorial in the documents section. It details how to upload code. You don't need the FTDI board once your code is uploaded (this saves on space).
• The digital D0 and D1 pins connect with the FTDI header's TXO and RXI pins. Because of this, they do wierd things when your board is connected to your computer via the FTDI breakout board. When you aren't connected to a computer, they work normally. I did some testing while connected to the computer, so I decided to use different digital pins (I had extra digital pins I wasn't using).
• It doesn't supply pins that give power for your components. Since I only needed 3.3v at a low amperage, I turned on an extra digital pin to supply power. If you need different voltages or more amps however, you'll need to add some external power to your components.

Thanks again to Sparkfun for this great component and tutorials!

The ATMega328P chip, crystal and bypass caps on an easy to use board. Already programmed with the Arduino bootloader.

Only one issue: I would put A4 & A5 on the edge and put A2 & A3 in the middle, because I2C is very popular, and the middle thing makes it awkward to use.

Otherwise, this is one of the best boards to use for low power - the leds and regulator are easy to remove, so the board draws the same current as a naked 328p. Perhaps I would also like to be able to solder a crystal to the board, rather than always use the internal 8 mhz oscillator.

I have built about a dozen projects with this board.

Excellent product and fast shipping to europe .

The support provided is amazing and enabled me to get up and running in minimal time.

Just wish they would re-do two things: OK, you had to stick A4, 5, 6, 7 in the middle: we're grateful to have them! But why stagger them off the .1" grid? Couldn't you put them on the .1" grid with the other pins so you can still pin them down in a .1" perf-board? Surely you could shuffle other components around by the .050" needed to keep them aligned. And please bring back the .062" thick PCB instead of the too-flimsy .032" boards used now. The old .062" thick ones were rigid enough to be sturdy when prying them back up out of a breadboard without deforming but when you try to pull the current Pro-Minis back out of a standard breadboard they flex badly, and that can't be good for the traces and solder pads. What do you gain by the thin boards? Other than that, (and please just view this as a constructive criticism) they are great, really handy when you need to throw a little smarts into a sensor or actuator project.

Yes it's "old". Yes, it's "limited".

So am I.

And this little beauty does what it says on the tin, is easy to use, never lets me down, and is inexpensive.

Yes, I have to use "bigger" Arduinos for some things. I have webservers running in the Dev Thing and a similar Huzzah. And smaller things are fun sometimes, too... I have the little Sparkfuns and some "Trinkets".

But for day to day things... I use this, or in some legacy situtions, the ModernDevice RBBB.

And if I need 3v3, there's the 3v3 version of this.

Just like @Member #162075 I too faced the dreaded magic smoke issue with a 9v - but in my case, it was working fine, until it wasn't. I'm pretty sure I must have accidentally reversed polarity though! It is so easy to accidentally do that, and a mere touch is all it takes the fry the puppy. And it is only the voltage regulator - the rest of the board is fine when connected via VCC from the FTDI header. Also, I disconnected the wires as soon as I saw a little whiff of smoke, but the damage was done. Connecting anything to RAW at that point just exacerbated the problem and caused a slow but sure death.

Just make sure to handle reverse polarity in the circuit connecting to RAW and GND. Even a simple diode (I used the IN4001) protecting the polarity, while not the best solution (you have to account for the voltage drop of about 0.5-0.7v across the diode), it is still infinitely better than directly hooking up the input source to RAW and GND. After that approach, a second Arduino Pro Mini is chugging along fine with the 9v battery, and you don't have to worry about accidentally touching the wrong 9v battery leads to the connector and shorting the whole thing!

In all, a great little board for making a permanent/semipermanent board that is cost effective and small.

I'm using this in a solar charger project I have and wanted to share my suggestions. 1) I cannot get the Serial RX to work or receive anything from Serial Monitor. I have confirmed with both a logic analyzer and oscilloscope that the RXI pin is being driven with proper 3.3V UART and the bytes and settings are correct. I can transmit (println()) just fine and see the output on the Serial Monitor. Not having serial RX is limiting my project to not being able to run a calibration routine (receive measurements from host and calibrate). I don't think it's possible that I damaged the RXI pin, because I can download code just fine. Serial.available is never > 0 no matter what I send, meaning that it never receives any serial, but testing shows it does have the proper signals.
2) There is no AREF pinout, this would be nice to have and essential. It's especially useful for my application where it would be safer to have a stable Analog reference to not accidentally misread the battery and solar voltages and create a charging safety issue (overdrive the battery, throw off MPPT algorithm and create instability, ...).

Overall it's a cool board and nice form factor!

I love these boards, getting the 8mhz version is an easy way to start a low power project!

I needed an inexpensive and physically small 3.3V processor for my project and this Pro Mini fit the bill.beautifully. Having the on-board regulator allows the system to be powered from a 12V source which was needed elsewhere in the system was also an advantage. However, because my system is battery-powered I did need to eventually disable the regulator and provide an external source of 3.3V. Fortunately the board provides an easy means to disable the power-hungry regulator.

is there anything better than this tiny, easy to use computer?

Works exactly like it should so 5 stars.

these are awesome little development boards. Highly recommend the FTDI breakout programmer, makes life very easy. This board is very thin, compact, and has plenty of IO options. Easy to solder.

Of course it's awesome, it's from Sparkfun.

Useful as low-cost and already-wired processor in testing data communication (RS232) programming with a PC serial port by assembly-language and by the Arduino IDE

If you need to integrate a small ready-to-use arduino/ATmega in your project this is a pretty great little board. this is made to be as small as portable as possible. Even the PCB itself is thinner then usual.

I've been using the Pro Mini boards since they were first introduced and they're just the ticket if you need a super small Arduino board for your project. I like to keep a few of both 3.3V and 5V versions on my bench as they're my go to board for quickly prototyping circuits.