Introduction: Microduino: a Small and Stackable Arduino

About: Microduino: small, smart, stackable Arduino compatible boards

In November 2012, I designed the first version of Microduino, a compact size Arduino Uno compitable board. it's small and stackable.

The idea of Microduino is building Arduino Uno circuit in two seperate boards: an arduino minimum system (named as Microduino-Core) and a ttl2usb board (named as Microduino-FT232R). the pinout of two boards is well defined as a U-shape 27 pinout, 27 signals is carefully arranged and utilized, so that the two board can be stacked together, functioning as an Arduino-Uno board. 

the size of Microduino is as 1.0inch x 1.1inch, just like a quarter. it's very small. the pin heads and socket can be stablely connected, it means Microduino can be used in a low volume design production!

it's intersting expeirence, I'd like to share it with you. All Microduno boards are completely open source, check here and find more information! . if you want to know more information about Microduino, please check my facebook

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Step 1: The First Vesion Microduino

The purpose of designing Microduino was to build a small device to monitor server room temperature remotely. I actually had already built a prototype with Arduino. However, as you know, the size of Arduino was really big. I searched for smaller Arduino compatible board with no luck, and decided to design my own.

To decrease the board size without sacrificing performance, usability, and extendibility, I split the Arduino-Uno circuit into two parts: the -Core circuit, functioning as an Arduino minimum system, and the -FT232R circuit, communicating between PC and -Core. A U-shape 27 pinout was also well defined and utilized for better functional extension.

Microduino-Core and Microduino-FT232R stacking together matchs the power of Arduino-Uno. the size is small .

Step 2: Remote Temperature Monitor With the First Version Microduino

Afterwards, I designed several other extension boards: -Enc for Ethernet communication; -nRF24 for wireless communication in 2.4G frequency; and a -SD card for recording temperature history.

I stacked the boards together and connected temperature sensor in a standard hole board – BTW, Microduino is compatible with a standard hole board, but Arduino is not. Then, Arduino program was developed to make the device work. With this small device, temperature data can be automatically pushed to internet; so I can even real-time monitor the server room temperature at home. I built 8 sets of this device, and they have been working well till today.

Step 3: The Final Version of Microduino-Core and Microduino-FT232R

Microduino is Arduino compatible and completely open-source. Microduino is small. The board is only 1.0 inch X 1.1 inch, the size of a quarter. It's stackable, every Microduino board can be easily stacked together through U-shaped pins.

Over several months testing, we have made several revising, the boards are finalized. Microduino-Core + Microduino-FT232R both match the power of an Arduino-Uno board. it's completely compatible with Arduino development environment.

the boards are completed open source, you can find source files here:

Microduno-Core Assembly variant:
Part     Value                             Package             Library  Position (mil)        Orientation
C1       0.1uF                             0603-CAP            00my     (362.5 500)           R270
C3                                           0603-CAP            00my     (868 293)             R45
C4                                         EIA3528             00my     (312.5 300)           R90
KEY1     KEY-TES-018                       KEY-TS-018          00my     (87.5 712.5)          R90
LED1     L-AMBER                           0805-LED            00my     (100 512.5)           R180
R1       510                               0603-RES            00my     (212.5 525)           R270
R2       1000                              0603-RES            00my     (262.5 737.5)         R270
R3       0                                 0603-RES            00my     (125 262.5)           R90
R4       0                                 0603-RES            00my     (200 262.5)           R90
U$1      PING-MICRDUINOPIN-MICRODUINO-1009 PIN-MICRODUINO-1009 00my     (0 0)                 R0
U1       ATMEGA328P-AU                     TQFP-32             00my     (657.5 735)           R225
Y1       16MHz                             RESONATOR-SMD       00my     (511 762)             R45

Microduino-FT232R Assembly variant:
Part     Value                             Package             Library  Position (mil)        Orientation
C1       0.1uF                             0603-CAP            00my     (437.5 525)           R270
C2       10uF                              EIA3528             00my     (325 637.5)           R270
C3       0.1uF                             0603-CAP            00my     (450 275)             R90
C4       0.1uF                             0603-CAP            00my     (650 800)             R0
D1       MBR0520                           SOD123              00my     (512.5 700)           R90
GREEN-TX                                   0805-LED            00my     (125 237.5)           R90
IC1      FT232RLSSOP                       SSOP28DB            00my     (712.5 387.5)         R180
R1       1k                                0603-RES            00my     (887.5 687.5)         R90
R2       1k                                0603-RES            00my     (787.5 687.5)         R90
R3       330                               0603-RES            00my     (312.5 787.5)         R0
R4       330                               0603-RES            00my     (300 262.5)           R0
R5       4k                                0603-RES            00my     (675 687.5)           R90
RED-RX                                     0805-LED            00my     (125 762.5)           R90
U$7      PING-MICRDUINOPIN-MICRODUINO-1009 PIN-MICRODUINO-1009 00my     (0 0)                 R0
USB1     MICRO_USB-B                       USB_MICRO_B         00my     (95.5 500)            R270

Step 4: Microduino Extension Modules

consequently, I designed a series of Microduino extension modules. Every Microduno module adapt uniformed UPin-27 pinout, and it's well configured across different modules, without any signal conflict.

it's very easy for designers to append various features in your design prototype and idea realization.

all modules are open source ! check eagle file at


The Microduino-Enc features an Ethernet port.
The Microduino-nRF24 enables wireless communication in 2.4GHz frequency.
The Microduino-SD features an SD card slot.
The Microduino-BM manages Li-ion battery operation.
The Microduino-BT is for bluetooth communication.
The Microduino-10DOF is for vector meter, which can be used in Robot and QuadCopter
The Microduino-RTC is a RTC module
The Microduino-LM4863 is a D-Class amplifier.
The Microduino-A3986 is a motor driver
The Microduino-NEO-6M is a GPS module
The Microduino-CC3000 is a Wifi module
The Microduino-[BT] is BLE shield

Step 5: The U-Shape Pinout of Microduno: UPin-27

A U-shape 27 pinout is used and well configured to make these boards well connected without any functional signal conflict.

Step 6: Various Applicaitons With Microduinos

with Microduinos modules, you can easily design your own applications. 
like a network gate, a music box, a robot, smart your room and garden, a quadcopter and anything interesting.

enjoy the journey of Microduino!

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