Nicla Family Form Factor Specification

Our smallest footprint packed with advanced features.

This document aims to describe the design philosophy and technical specifications of the Nicla Form Factor and should be used as a guideline for designing boards and accessories (shields/carriers) compatible with the form factor.

Nicla Form Factor

The Nicla form factor has been designed to address the needs of industrial applications and makers for an all-in-one package featuring wireless sensing capabilities. Key focus is given to collecting and processing data at the edge with minimal power consumption. Nicla boards integrate application specific sensors and high performance microcontrollers capable of processing raw data in real time and provide high level measurements to the host board or to the main application. Nicla boards support programmable I/O voltage ranging between 1.8 and 3.3V whose voltage reference can either be supplied externally or generated internally.

Nicla family has been designed to fulfill the following key needs:

  • Low Power
  • integrated sensing with AI capabilities
  • wireless communication
  • partial compatibility with MKR form factor
  • industrial temperature range

Nicla boards are designed for the following three use cases:

  • Standalone - Nicla boards can be used as a traditional Arduino board on which the user can load the final application. In this scenario Nicla's microcontroller is executing the whole application and its interfaces can be used to communicate to external sensors and actuators
  • ESLOV peripheral - Nicla boards can be connected through the ESLOV connector, consisting of 5 pins including an I2C bus, power supply and a GPIO. Through this connector the board can be interfaced with MKR boards directly or, via adapter cables, to other boards exposing similar interfaces such as QWIIC, STEMMA/STEMMA QT and GROVE. Nicla boards are provided with a readymade firmware which abstracts sensors and allows reading high level measurements processed by Nicla main processor.
  • MKR Shield - Nicla boards can be fitted on a MKR board as a shield. In this scenario MKR would be running the main application and would communicate with Nicla through I2C as it would do via ESLOV.
  • Wireless - Nicla boards can be battery operated and can communicate wirelessly to a central processor. As in other use case scenarios Nicla would be processing sensor data and provide high level processed information.

Mechanical Specification

Board Size and Shape

Nicla form factor shape is a square with 900 mils edge length, excluding the protrusions of connectors which are meant to be passing though a case. Although board is square its shape and its connectors are asymmetric to prevent connecting the board in the wrong orientation.

Nicla board quotes
Nicla board quotes

In order to create a consistent ecosystem and allow creation of cases usable across all the family, Nicla form factor fixes the following mechanical positions:

  • board to board connectors
    • I/O Headers
    • debug fins
  • USER Interface
    • pushbutton
    • RGB LED
  • Board to cable connectors
    • USB connector
    • Battery Connector
    • ESLOV connector


Nicla header quotes
Nicla header quotes


Nicla fins quotes
Nicla fins quotes

User Interface

Nicla user interface quotes
Nicla user interface quotes


Nicla connector quotes
Nicla connector quotes

Power Supply

Nicla boards can be powered from four different power supply rails:

  • USB connector
  • ESLOV connector
  • Vin pin
  • Battery

When powered from USB, Vin or ESLOV the board can charge the battery if software is programmed to allow it. All voltages can be present at the same time without causing any issue as the three voltages are ORed through diodes. Vin pin is directly connected to the PMIC whereas the other two pass through diodes, which means that ESLOV connector will not be able to power external devices and is meant primarily as a peripheral.

Nicla boards provide an on board battery charger for single cell LiPo batteries which have a programmable charge current depending on the specific board. All boards provide sleep mode functionality which minimizes current draw from battery, keeping the system off until the reset button is pressed.

External Interfaces


Header I/O pins are driven by a bidirectional voltage translator that allows decoupling I/O Voltage from internal CPU voltage. Header pins are referenced to the VDDIO pin which can either be generated internally with a programmable voltage or fed externally. Board has two columns of header+castellated pins that are partially compatible with MKR form factor. Specifically Nicla boards are designed so that a nicla board can be fitted in the first half of the MKR connectors.

Using this connection it's possible to use Nicla as a shield for MKR or Nicla as a controller for MKR shields provided the shield doesn't use the missing pins.


PinNameMKR PinDescription
J1-8ADC1A0Analog Capable Pin
J1-7ADC2A1Analog Capable Pin
J1-6SCLKA2SPI clock
J1-5CIPOA3SPI Controller Input/Peripheral Output
J1-4COPIA4SPI Controller Output/Peripheral Input
J1-3CSA5SPI Chip Select
J1-2ADC3A6Analog Capable Pin
J1-1GPIO0A7General Purpose IO
PinNameMKR pinDescription
J2-9VIN+5VInput Supply Voltage
J2-8-VINNo Connection
J2-7VDDIO+3V3Header I/O Voltage
J2-6GNDGNDReference Ground
J2-2SCLD12/SDAGPIO/I2C SDA, shared with ESLOV
J2-1SDAD11/SDAGPIO/I2C SCL, shared with ESLOV
PinNameMKR pinDescription
J3-2VBAT-Battery Positive Terminal
J3-1NTC-optional NTC Sensor for Battery Overtemperature Protection


Nicla boards have a set of fins interleaved among headers that are mainly for debug and initial programming. These pins are arranged so that they can easily be contacted by inserting the board in a 1.27mm/50 mil dual row header that would allow firmly contacting the fins along with header pins, provided no header has been soldered on it. The functions of each fin is specific to a board but SWD pins for on board processors have been set up so that they are consistent across boards.


P-8AUX3Auxiliary Pin 3
P-7+1V8Internal 1.8V Supply
P-6AUX2Auxiliary Pin 2
P-5RESETMain MCU Reset Pin
P-4SWCLKMain MCU SW Debug Clock
P-3SWDIOMain MCU SW Debug Data
P-2AUX1Auxiliary Pin 1
P-1AUX0Auxiliary Pin 0


Battery terminals are available either via a 3 pin connector or via headers. In both cases supported battery is 1 cell Lithium Polymer. Please check board datasheet for available charge current options and make sure to never charge the battery at more than the recommended max limit. If possible use the provided NTC terminal to connect a Negative Temperature Coefficient resistor to sense battery temperature so that charging can be stopped in case battery temperature reaches the programmed limit.


J4-3GNDBattery negative terminal
J4-2NTCoptional NTC sensor for battery overtemperature protection
J4-1VBATbattery positive terminal


ESLOV is a 5 pin connector available on MKR and Portenta boards and can be used to connect to a Nicla via cable. Through this connector the board can be interfaced with MKR and Portenta boards directly or, via adapter cables, to other boards exposing similar interfaces such as QWIIC, STEMMA/STEMMA QT and GROVE. Nicla boards are provided with a readymade firmware which abstracts sensors and allows reading high level measurements processed by the Nicla's main processor.


J5-4SDAGPIO/I2C SDA, Shared with Headers
J5-3SCLGPIO/I2C SCL, Shared with Headers
J5-2INTGPIO Referenced to VDDIO voltage
J5-1VESLOVESLOV Supply Input


USB connector consists of a micro USB with the Nicla only capable of acting as a peripheral. Voltage from this connector can be used to power the board. USB port can be used to program and debug the board or to expose custom application specific interfaces.

Contribute to Arduino

Join the community and suggest improvements to this article via GitHub. Make sure to read out contribution policy before making your pull request.

Missing something?

Check out our store and get what you need to follow this tutorial.

Suggest Changes

The content on is facilitated through a public GitHub repository. You can read more on how to contribute in the contribution policy.