Chinese board review: The Arduino Pro Mini 3.3V

The Arduino Pro Mini is one of the lesser known board as it isn’t designed by the official Arduino team. Instead, it is designed by hobbyist shop Sparkfun and is available on their website for $9.95.

On this review, we will take a look at the Pro Mini clone from ElectronicFans, one of the better known Chinese electronics hobbyist shops; offering them at $1.70.


Arduino Pro Mini?

One of the particularities of the board is that it is available in both 5V and 3.3V; the difference being the regulator used on the raw power supply. Other than that, if you provide a regulated power supply you could technically run the 5V version at 3.3V; it’s however not really recommended. Indeed, the 5V version has a 16Mhz crystal resonator while the 3.3V boasts a 8Mhz version. At 3.3V, the microntroller might not be stable at 16Mhz. Besides, 8Mhz is a smart choice for low power embedded products.

Other than that, the Arduino Pro Mini will behave exactly like an Arduino Uno, as they both embed the Atmega328P chip.


Chinese Clone

The board came in a static protection bag, and is exactly as described. It contains header pins if you wish to make it breadboard friendly.


A quick review of the components on board allow us to see that the 3.3V regulator used on this clone is a MIC5219-3.3BM5. It’s a pretty good linear voltage regulator that accepts raw voltage from 2.5 to 12V; with a maximum current of 500mA. This should be plenty enough to power the board.


One small comment that can be made though: as the 5V and 3.3V are almost identical, a small marking at the back of the board is supposed to be etched with the board version. They were blanks. If you get both 5V and 3.3V within the same order, it might be very difficult to tell them apart!



Powering it on, I was pleasantly surprised that the board comes pre-programmed with a blink sketch that will blink the onboard LED (and output on pin 13). This is a neat feature if you want to know if something is wrong with the board from the get go. Some Chinese Arduino clones also sometimes forgo entirely the on board LED, so this is a nice touch.

Uploading your own sketch is a piece of cake. From the Arduino IDE, select “Arduino Pro or Pro Mini” and “ATmega328 (3.3V, 8Mhz)” as processor, select the correct COM port then click upload.


… Wait; there is something missing! The Pro Mini does not come with a USB port. It must be programmed with a USB to Serial converter. ElectronicFans also sell these for $1.60 so be sure to pick one up if you don’t already have one.

The serial adapter can be inserted directly on the Pro Mini and act as a temporary power source. You don’t need jumpers or any solder, the contacts touching should be enough to program successfully your Arduino Board.

The Pro Mini on a breadboard, with the USB to Serial adapter attached.
The Pro Mini on a breadboard, with the USB to Serial adapter attached.



This Pro Mini clone is very high quality. It rivals without any issue with the original board, and the only difference is the position of the A6 and A7 pins. It is otherwise an identical twin; well made and with good soldering.

If you plan on using an Arduino Uno for your next project, consider the Pro Mini instead.

Verdict: GoodScore - Good

The Good The Bad
  • Good soldering job & quality components
  • Pre-loaded blink sketch
  • 100% compatible with the official design
  • Beware of the A6/A7 pins different placement




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