Creative Commons images are CC BY-NC-SA 3.0


added to your
shopping cart

25 available 25 in stock
19.95 1+ units
17.96 10+ units
15.96 100+ units

Description: Here at SparkFun, we refuse to leave 'good enough' alone. That's why we're adding to our line-up of Arduino-compatible microcontrollers once more! The Pro Micro is similar to the Pro Mini except with an ATmega32U4 on board. The USB transceiver inside the 32U4 allows us to add USB connectivity on-board and do away with bulky external USB interface.

This tiny little board does all of the neat-o Arduino tricks that you're familiar with: 4 channels of 10-bit ADC, 5 PWM pins, 12 DIOs as well as hardware serial connections Rx and Tx. Running at 8MHz and 3.3V, this board will remind you a lot of your other favorite Arduino-compatible boards but this little guy can go just about anywhere.

This is the 3.3V version so, as always, keep in mind the limits of system voltage and so forth. The lower system voltage also has its advantages, though, like ease of use with many common 3.3V sensors. There is a voltage regulator on board so it can accept voltage up to 12VDC. If you're supplying unregulated power to the board, be sure to connect to the "RAW" pin on not VCC.

Not sure which Arduino or Arduino-compatible board is right for you? Check out our Arduino Buying Guide!

Note: See the GitHub link below for support with the Arduino IDE.

Dimensions: 1.3x0.7"


  • ATMega 32U4 running at 3.3V/8MHz
  • Supported under Arduino IDE v1.0.1
  • On-Board micro-USB connector for programming
  • 4 x 10-bit ADC pins
  • 12 x Digital I/Os (5 are PWM capable)
  • Rx and Tx Hardware Serial Connections
  • Our Smallest Arduino-Compatible Board Yet!


Comments 20 comments

  • Following the instructions in the Hookup Guide Tutorial but so far no luck installing driver on Windows 7 64. Downloaded driver ZIP-file from Device is detected properly as ‘USB IO Board’ in Device Manager but when I point the driver installation to the SF32u4_boards-master\driver directory I keep getting ‘Windows was unable to install your USB IO Board… Windows could not find driver software for your device’. Anyone know what’s up?

    • Figured it out with help of this: Sparkfun should update their tutorial and driver (INF) files. The rest of the tutorial looks ok.. I can upload the sample program to the board and it works ok.

  • Hi, I work with the Arduino Pro 3.3V “DEV-10914” and the FDTI basic 3.3V “DEV-09873.” Today, I want to work with Pro Micro 3.3V “DEV-12587” or fio v3 “DEV-11520.” How to flash my new board without the port USB converter 5V/3.3V ?

  • Does anybody know if the Pro Micro can support a display? If yes, what kind of display and how? (what kind of connection and how to program it) I have attached the pro micro with a bluetooth serial port module in order to send some dummy readings to an android app via bluetooth and I would like to have these readings shown on a display as well. Thank you

  • Has anyone run into problems using the EEPROMex library on these Pro Micro boards? I used that library flawlessly on an Arduino Uno, but I think using it bricked by Pro Micro 5V (I was able to recover it by reflashing the bootloader:—easy-way), but I’m wary of trying again. Any ideas on how to easily use EEPROM memory would be fantastic! Thanks!

  • after my initial prototyping with Pro Mini’s, I bought a couple of Pro Micro units because it would eliminate the external power supply. following the instructions for the Addon files, i was able to program both units (one via a Mac, the other via Linux both with Arduino IDE 1.0.5) using an example from RF24 library to verify my wiring. the functioning setup was disconnected overnight and now neither board is recognized (i.e. the Mac and the Linux setup exhibit the same behavior). i’m stuck. this seems to be a known issue (e.g. and and is there a documented solution to this?

    • Update: Using windows 7 and arduino IDE 1.0.5 + the above addon files, I tried the recommended remedy for getting into bootloader mode and loading a sketch; i’ve not been able to get into bootloader mode (50+ tries).

      • last update synopsis: i’m able to see/program the boards again, but i don’t know why. long version: after unsuccessfully trying to get the IDE to see the board under windows via the bootloader mode reset x 2 sequence, i rebooted the mac into OS X and noticed that the serial port (/dev/tty.usbmodem1411) has reappeared. i was able to download the blinky test sketch into the board, switch to the second board and perform the same thing. i rebooted the linux and it was able to see the board again. my w-a-g is that there’s an issue with the USB dialect that the board uses.

        • Did you ever determine the cause and resolution? I have MANY styles of 5v Arduinos that appear fine on my Mac. I have exactly two 3.3v devices and neither show up in the IDE, but this one (the DEV-12587) doesn’t even show up in system information.

          When I first connected it, it showed up as a keyboard and I sent a modified blink code to it. Since then I can’t see it in the IDE port list anymore. This is on two different computers (both running Mavericks, though).

          Would love to find a fix.

          • I’m having the same problem. I was programming it one day and all of a sudden it stopped showing up in my Windows 7 Device Manager (regardless of the USB port I was using [I’ve had trouble using it on my USB 3.0 port]). When I do the “double tap” reset trick to get it into bootloader mode, my Windows 7 Device Manager flickers as if it were recognizing a new device, and the Arduino IDE see it on Port 9 for a few seconds. I haven’t been able to successfully upload a sketch to the Arduino while doing this though. I wish we could find a fix.

  • Could you please specify the quiescient current at poiwer down? Thank you

  • I’ve got a few of these, and was wondering if I could convert one of them to 5V by simply changing the Crystal to 16Mhz, soldering the jumper closed, and flashing with the Caterina_promicro16.hex bootloader?

  • I developed HID keyboard using example source.

    However, BIOS does not work on the problem. (Mac, Windows in normal operation.)

  • This is a fantastic deal!

  • I’m looking at the schematic and it looks like there’s either an error in the board or the schematic:

    The silkscreen on the board has pins on the bottom corner labeled 10, 16, 14, 15, A0, etc. The schematic shows those same pins as D10, MOSI, MISO, SCK, A0, etc. This is mostly ok as D16==MOSI and D14==SCK. However, D14 is not the same as MISO. According to the schematic, D14 is connected directly to the RX LED. Either the schematic or the silkscreen should be updated.

    • I think the schematic is wired correctly, but labelled wrongly: PB0(SS) is Arduino pin D17, and PB3(MISO) is Arduino pin D14. The PCB is correct.

    • I agree that the confusing naming is, well, confusing. Basically you’re thinking ‘Pin 14 on the header, that must be the same as D14 in the schematic’, while it’s not. Gets even more fun when you try to figure out which pin number that would be on a various traditional arduino boards :)

  • What type of micro-USB connector are you using on this? It looks MUCH easier to solder than the ones I’ve been messing around with!

    • The easier to solder connectors are not necessarily a good thing. I’ve had several micro-USB connectors snap off of 5V Pro Micros while attaching a USB cable, lifting traces in the process and generally being a big pain to repair. Maybe the solder pads to the left and right of the connector should be made a little larger to give the connector a little more footing on the board.

      • That’s one of the reason for the change. The new boards have a new connector with a more secure footprint to help prevent that accidental removal.

Related Products