The Arduino Pro Mini is a small board with all surface mount parts. It has all of the I/O of the Arduino Uno, plus the addition of two more analog inputs. There are a couple of models of this card, one 5V/16MHz, and one 3.3V/8MHz.
There is nothing on it that doesn’t contribute to the basic functionality of the ATmega328. You could buy a knock-off Arduino Uno for a little less, but in fact it has too much on it! If you are doing basic R&D – use the Uno. It allows us to use shields, which provide modules we may need. When the R&D is done, out come the Arduino Pro Minis for the actual finished project.
The pins on the Arduino Pro Mini and the Arduino Pro Micro are about the same, upto the SPI port on 11, 12, and 13. At that point, the Pro Micro changes to 14, 15, and 16. The PWM pins on the Pro Mini are identified by circles around the pin, just like the Pro Micro.
It must be someone else’s favorite, too, because it is one of the most copied boards out there. Not every copy is an exact copy, though, even the originals! For an example, see the image below:
As you can see from the image, there are four different boards, with different pinouts, all calling themselves Arduino Pro Mini. The ones that actually are Pro Minis are identified by the Sparkfun logo to the left of the ATmega328. Yet even they are different. The one in the lower left has A0-A7, while the one in the lower right has only A0 through A5. The one in the upper left has A0-A7 and an SPI port. The one in the upper right has A0-A7, but A6 & A7 are on the end of the board.
The small-form-factor boards are similar, but all significantly different. This comparison puts the differences in one place to make them easier to see.
The Pro Mini and Pro Micro of any brand of Arduino compatible board seem to be very popular. But choosing between them can be tough. There seem to be so many, and it is hard to distinguish between them. Here is a comparison on the size and features.
$7 – $10
$6 – $20
$12 – $35
$7 – $25
The prices given above are a range from the cheapest clone to the most expensive genuine article in January 2014. Used in a development environment, where things are plugged and unplugged, powered up and down, jerked around on cables, the clones don’t hold up as well. Reports show failures from all of them clones or downright forgeries, and all from abuse. There has been no reports of failure in the field of either a clone or an original.
The Deek-Robot Pro Mini is nearly identical to the Sparkfun Arduino Pro Mini. It has all of the I/O of the Arduino Uno, plus two more analog inputs. There is only a 5V version of the board. The “extra” I/O is at the end opposite the programming connector. This is slightly different than the Sparkfun Arduino Pro Mini boards, which have the analog pins in an unhandy position in the interior of the board. Either way, you can’t put pins in them and use them on a breadboard (the pins would need to point up). With the Deek-Robot Pro Mini, the extra pins at the end are at least on the same 0.1″ centers as the rest of the connectors, even though A4 and A5 are off by 0.05″.
The Deek-Robot Arduino Pro Mini is probably the most ripped off board there is. Everyone is counterfeiting the board, or at least stealing the name. That is likely because it is the most popular of the small form factor boards by far.