KiCad Arduino Library: Uno, Nano, Mega & Pro Micro Footprints

Designing custom PCBs that interface with Arduino boards should be straightforward, yet finding reliable KiCad Arduino libraries has frustrated makers and engineers for years. Arduino officially provides EAGLE files for their boards, but KiCad users have been left to rely on community-maintained libraries of varying quality.

The good news is that the ecosystem has matured significantly. Today you can find well-maintained KiCad libraries covering everything from the classic Arduino Uno to the compact Arduino Nano, the powerful Arduino Mega 2560, and the keyboard-favorite Arduino Pro Micro. This guide walks you through the best library sources, installation methods, and practical tips for using Arduino footprints in your PCB designs.

Whether you’re creating a custom shield, designing a carrier board, or building a complete project with an embedded Arduino module, understanding which library to use and how to install it properly will save you hours of frustration and potential board respins.

Understanding Arduino KiCad Library Types

Before diving into specific libraries, understanding the different footprint types available helps you choose the right one for your application.

Shield vs Socket vs Tile Footprints

Footprint Type	Description	Use Case
Shield	Arduino plugs in from beneath your PCB	Creating add-on boards that stack on top of Arduino
Socket	Arduino plugs in from above your PCB	Carrier boards where Arduino sits on top
Tile	Arduino solders directly using SMD pads	Permanent installations, production boards

Most hobby projects use Shield footprints because they match the traditional Arduino shield concept. Socket footprints work well for test fixtures or when you need easy Arduino removal. Tile footprints provide the most compact solution but require castellated-edge Arduino boards or careful soldering.

Pin Header Configurations

Different Arduino boards use different header arrangements. Getting the dimensions wrong means your board won’t fit.

Arduino Board	Pin Count	Row Spacing	Pin Pitch
Arduino Uno R3	32 pins	Variable (not uniform)	2.54mm
Arduino Nano	30 pins	15.24mm (0.6″)	2.54mm
Arduino Mega 2560	86 pins	Variable	2.54mm
Arduino Pro Micro	24 pins	15.24mm (0.6″)	2.54mm
Arduino Micro	34 pins	15.24mm (0.6″)	2.54mm
Arduino Due	86 pins	Variable	2.54mm

The Arduino Uno has that infamous non-standard header spacing that’s caused countless frustrations. The inner headers are offset by 0.16″ (4.06mm) from the standard 0.1″ grid, a decision made early in Arduino’s history that stuck around for compatibility.

Primary KiCad Arduino Library Sources

Several well-maintained libraries cover Arduino boards. Here’s what each offers and when to use them.

Alarm-Siren Arduino KiCad Library (Recommended)

This is the most comprehensive Arduino KiCad library available, now distributed through KiCad’s official Plugin and Content Manager (PCM). The library covers virtually every Arduino board variant with both symbols and footprints.

Included Arduino Boards:

Board Family	Variants Included
Arduino Uno	R1, R2, R3, R3 SMD, R4 Minima, R4 WiFi
Arduino Nano	Classic, 33 BLE, 33 BLE Sense, RP2040 Connect
Arduino Mega	2560 R3
Arduino Micro	Standard
Arduino Due	Shield footprint
Arduino Pro Mini	Socket footprint
Arduino MKR	1000 WiFi, WiFi 1010, Zero, and more
Arduino Leonardo	Shield footprint
Clone Boards	Mega 2560 Pro, Pro Mini clones

This library uses consistent naming conventions and includes proper symbol-to-footprint associations, meaning less manual configuration work.

g200kg KiCad Arduino Library

A lightweight alternative focusing on the most commonly used small-form-factor boards. This library includes 3D models, which the Alarm-Siren library lacks in some cases.

Included Boards:

• Arduino Micro
• Arduino Nano
• Arduino Nano Every
• Arduino Pro Mini
• SparkFun Pro Micro

The 3D models are provided in X3D format (exported from Blender), which works well in KiCad’s 3D viewer for mechanical clearance checking.

SparkFun KiCad Libraries

SparkFun maintains their own KiCad library that includes the popular SparkFun Pro Micro and other SparkFun-specific boards. If you’re using genuine SparkFun products, this library ensures accurate footprints.

The SparkFun library also includes production IDs and internal part numbers useful for manufacturing but can be ignored for hobby use.

Installing the Arduino KiCad Library via PCM

The easiest installation method uses KiCad’s built-in Plugin and Content Manager, available in KiCad 7 and later.

Step 1: Configure Library Prefix

Before installing, verify your library nickname prefix setting. Open KiCad and navigate to Preferences → Preferences. In the Plugin and Content Manager section, ensure “Library nickname prefix” is set to “PCM_”. This prefix ensures footprint references resolve correctly.

Step 2: Open Plugin and Content Manager

Click the Plugin and Content Manager button in KiCad’s main window.

Step 3: Find and Install the Library

Select “KiCad official repository” from the dropdown. Navigate to the Libraries tab and search for “Arduino.” Locate “KiCad Library for Arduino Modules” and click Install.

Step 4: Apply Changes

Click “Apply Changes” and wait for the download to complete. The library will appear in your Installed tab.

Step 5: Verify Installation

Open the schematic editor and press ‘A’ to add a symbol. Search for “Arduino” and you should see entries prefixed with “PCM_arduino-library.” The footprints automatically associate with the symbols when using this installation method.

Manual Arduino KiCad Library Installation

For KiCad 6 or when you need specific library versions, manual installation works reliably.

Downloading Library Files

Clone or download the library from GitHub:

git clone https://github.com/Alarm-Siren/arduino-kicad-library.git

Or download the ZIP file and extract it to your preferred KiCad libraries folder, such as:

• Windows: C:\Users\YourName\Documents\KiCad\libraries\
• macOS: ~/Documents/KiCad/libraries/
• Linux: ~/kicad/libraries/

Adding Symbol Library

Open KiCad’s schematic editor and navigate to Preferences → Manage Symbol Libraries. Click the folder icon to add an existing library. Navigate to your extracted folder and select the .kicad_sym file. Set the nickname to “arduino-library” (without PCM_ prefix for manual installs).

Adding Footprint Library

Open the PCB editor and go to Preferences → Manage Footprint Libraries. Click the folder icon and select the .pretty folder from your extracted library. Use the same nickname as the symbol library for consistency.

Arduino Uno KiCad Footprint Details

The Arduino Uno KiCad footprint requires special attention due to its non-standard header spacing.

Arduino Uno R3 Shield Dimensions

Measurement	Value
Board width	68.6mm (2.7″)
Board length	53.3mm (2.1″)
Mounting holes	4x, 3.2mm diameter
Digital header (D0-D13)	18 pins
Analog header (A0-A5)	6 pins
Power header	8 pins
ICSP header	2×3 pins

The offset between the lower headers creates the 0.16″ (4.06mm) misalignment that makes Arduino shields incompatible with standard 0.1″ grid prototyping boards. The Alarm-Siren library handles this correctly, but always verify with a 1:1 printout before manufacturing.

Arduino Uno R4 Considerations

The newer Arduino Uno R4 (Minima and WiFi variants) maintains backward compatibility with R3 shields but adds additional pins. The library includes separate footprints for R4 boards to capture these extra connections.

Arduino Nano KiCad Footprint Guide

The Arduino Nano KiCad footprint is popular for compact projects. Its breadboard-friendly form factor uses standard 0.6″ (15.24mm) row spacing.

Arduino Nano Pin Configuration

Pin Row	Pins	Functions
Left side	D1/TX through D12	Digital I/O, Serial, PWM
Right side	VIN through A7	Power, Analog inputs
Bottom	ICSP	Programming header

The classic Arduino Nano V3 uses 30 pins total (15 per side). Newer variants like the Nano 33 BLE and Nano Every maintain the same footprint dimensions but may have different pin functions.

Socket vs Through-Hole Considerations

Most Arduino Nano KiCad footprints use through-hole pads sized for standard 0.1″ headers. If you plan to solder the Nano directly to your board (without headers), look for “Tile” variants with SMD pads that match the Nano’s castellated edges.

Arduino Mega KiCad Library Setup

The Arduino Mega 2560 KiCad footprint is the largest of the standard Arduino boards, with 86 total header pins plus ICSP.

Arduino Mega 2560 R3 Header Layout

Header Section	Pin Count	Purpose
Digital 22-53	32 pins	Extended digital I/O
Digital 0-21	22 pins	Standard digital + Serial
Analog 0-15	16 pins	Analog inputs
Power	8 pins	Power distribution
Communication	8 pins	I2C, Serial
ICSP	6 pins	Programming

The Mega’s header arrangement includes double-row headers on one side, making footprint orientation critical. Always mark pin 1 clearly on your silkscreen.

Clone Board Compatibility

Many Mega clones, particularly the “Mega 2560 Pro” compact variants, use different form factors. The Alarm-Siren library includes specific footprints for these clone boards since their dimensions don’t match the official Arduino Mega.

Arduino Pro Micro KiCad Footprint

The Arduino Pro Micro KiCad footprint serves the mechanical keyboard community extensively. This compact ATmega32U4-based board fits in the same footprint as the Arduino Nano but includes native USB support.

Pro Micro Specifications

Specification	Value
Pins	24 (12 per side)
Row spacing	15.24mm (0.6″)
Pin pitch	2.54mm
USB	Micro-B (native)
Voltage	5V or 3.3V variants

Multiple Library Sources for Pro Micro

Several libraries provide Arduino Pro Micro KiCad footprints:

Library	Notes
Alarm-Siren	Included as part of main Arduino library
g200kg	Includes 3D model
Biacco42/ProMicroKiCad	Keyboard-focused with mounting variants
SparkFun KiCad Libraries	Official SparkFun footprint

The Biacco42 library deserves special mention for keyboard designers. It includes an “EnforcedTop” variant that covers one side’s pads with soldermask, preventing accidental reverse mounting, a common problem in keyboard builds.

Arduino Micro KiCad Symbol and Footprint

Don’t confuse the Arduino Micro with the Pro Micro. The Arduino Micro KiCad footprint is for the official Arduino board with 34 pins, while the Pro Micro has only 24 pins.

Arduino Micro vs Pro Micro Comparison

Feature	Arduino Micro	Pro Micro
Pins	34	24
MCU	ATmega32U4	ATmega32U4
USB	Micro-B	Micro-B
Manufacturer	Arduino	SparkFun/Clones
Price	Higher	Lower

If you’re working with genuine Arduino Micro boards, use the Arduino Micro footprint from the Alarm-Siren library. For SparkFun Pro Micro or clones, use the Pro Micro footprint.

Arduino Due KiCad Library Resources

The Arduino Due KiCad footprint follows the Mega form factor but uses 3.3V logic. The Due’s 32-bit ARM Cortex-M3 processor makes it popular for audio and signal processing projects.

The Alarm-Siren library includes Arduino Due Shield footprints. For carrier board designs, you may need to create a custom socket footprint or use one from SnapMagic (formerly SnapEDA).

Due-Specific Considerations

The Due runs at 3.3V and is not 5V tolerant on most pins. When designing shields, ensure your circuit doesn’t exceed 3.3V logic levels, even though the footprint physically fits both Uno and Due.

Verifying Footprints Before Manufacturing

Never trust any downloaded footprint without verification. This applies to all library sources, including well-maintained ones.

Verification Checklist

Check	Method
Pin spacing	Measure on printed 1:1 scale
Pin numbering	Compare to official Arduino pinout
Mounting holes	Verify diameter and position
Board outline	Check overall dimensions
Silkscreen	Confirm orientation markers

Print Test Method

Before ordering PCBs, print your board layout at exactly 1:1 scale. Place your actual Arduino board on the printout and verify all pins align with their pads. Check that mounting holes (if used) align properly. This simple step catches most footprint errors.

KiCad Arduino Library Resources and Downloads

Primary Library Downloads

Resource	URL	Contents
Alarm-Siren Arduino Library	github.com/Alarm-Siren/arduino-kicad-library	Most comprehensive, PCM available
g200kg Arduino Library	github.com/g200kg/kicad-lib-arduino	Nano, Micro, Pro Mini with 3D models
SparkFun KiCad Libraries	github.com/sparkfun/SparkFun-KiCad-Libraries	SparkFun products including Pro Micro
Biacco42 Pro Micro	github.com/Biacco42/ProMicroKiCad	Keyboard-focused Pro Micro variants
Freetronics Library	github.com/freetronics/freetronics_kicad_library	Arduino shields plus Raspberry Pi

Component Download Services

Service	Features
SnapMagic (SnapEDA)	Individual board downloads, multiple formats
Ultra Librarian	Manufacturer-verified footprints
Component Search Engine	Free symbol/footprint search

Official Arduino Resources

Resource	URL
Arduino Hardware Documentation	docs.arduino.cc/hardware
Arduino Store (board specs)	store.arduino.cc
Arduino GitHub	github.com/arduino

Frequently Asked Questions

Where can I find an Arduino Uno KiCad footprint for shield design?

Install the Alarm-Siren library via KiCad’s Plugin and Content Manager. Search for “KiCad Library for Arduino Modules” in the Libraries tab. After installation, you’ll find Arduino_Uno_R3_Shield (and other variants) in both the symbol and footprint browsers. This library correctly handles the non-standard 0.16″ header offset that makes Uno shields tricky to design.

How do I add Arduino Nano to my KiCad project?

The fastest method is installing via PCM (KiCad 7+): open Plugin and Content Manager, find “KiCad Library for Arduino Modules,” and install. For older KiCad versions, download the Alarm-Siren library from GitHub, then add the symbol library via Preferences → Manage Symbol Libraries and the footprint library via Preferences → Manage Footprint Libraries. The Arduino Nano Socket footprint works for most carrier board applications.

Is there a KiCad library for Arduino Pro Micro compatible with keyboard designs?

Yes, multiple options exist. The Biacco42/ProMicroKiCad library on GitHub specifically targets keyboard designers with variants including an “EnforcedTop” version that prevents reverse mounting. Alternatively, the g200kg and Alarm-Siren libraries include standard Pro Micro footprints. For genuine SparkFun boards, the SparkFun KiCad Libraries provide official footprints.

Why doesn’t Arduino provide official KiCad libraries?

Arduino historically used EAGLE for their PCB designs and provided EAGLE files for all their boards. As KiCad’s popularity grew, the community stepped in to create and maintain KiCad libraries. The Alarm-Siren library, while not officially affiliated with Arduino, has become the de facto standard and is now distributed through KiCad’s official Plugin and Content Manager.

Can I use the same KiCad footprint for Arduino Due and Mega?

The Arduino Due and Mega 2560 share the same physical header layout, so yes, the same shield footprint works for both. However, the Due operates at 3.3V while the Mega uses 5V logic. Your shield circuit must account for this voltage difference even though the footprint is mechanically compatible. The Alarm-Siren library includes separate symbols for Due and Mega to help track this distinction in your schematic.

Building Reliable Arduino-Based PCB Designs

With proper libraries installed and verified, designing Arduino-compatible PCBs becomes straightforward. Start with the Alarm-Siren library from KiCad’s PCM for the most comprehensive coverage. Supplement with SparkFun or specialized libraries when working with specific third-party boards.

Always verify footprints with physical boards before manufacturing, double-check pin numbering against official Arduino documentation, and consider voltage compatibility when designing for multiple Arduino variants. These practices prevent costly respins and ensure your custom shields and carrier boards work the first time.

The Arduino KiCad ecosystem has matured significantly from the early days of scattered, unreliable community footprints. Today’s libraries provide production-quality symbols and footprints that match or exceed what you’d expect from commercial EDA libraries. Take advantage of this excellent community resource and spend your time on circuit design rather than recreating basic footprints.