Terms

Alphabetical order

BLE

Bluetooth Low Energy is a wireless communication technology designed for low-power data transfer. Leafony uses it, for example, to send sensor readings to a compatible smartphone or computer. Both the device and the application need to support the connection. See the Bluetooth SIG technology overview for more information.

DC

DC stands for Direct Current, in which current flows in one direction. A DC motor operates from a DC power supply. The AIx1 Motor leaf uses a motor supply and a motor driver to control motors in response to MCU signals.

I2C

I2C stands for Inter-Integrated Circuit. It is a communication interface that connects a microcontroller to sensors and other devices. Devices share two signal lines, SDA for data and SCL for timing, and addresses identify the communication partner. Power and ground connections are also required. See the I2C address map for Leafony addresses and the NXP I2C-bus specification for details.

IoT/CPS

IoT stands for Internet of Things and CPS stands for Cyber-Physical Systems. In particular, CPS is a system that connects real physical and digital spaces without being connected to the internet.

Jumper pin

A small part placed over adjacent pins to connect them electrically, also called a shunt or shorting jumper. It is often used to change a board setting. It is different from a jumper wire, which connects terminals using a wire.

Jumper wire

A wire used to connect terminals, often for prototyping with breadboards or pin headers. Male ends plug into sockets, while female ends fit over pins. Choose the combination that matches the terminals you are connecting.

LCD

LCD stands for Liquid Crystal Display, a type of screen used to display text, numbers, or images. Leafony’s AI04 LCD is a character display with two rows of eight characters.

Leaf

It is the basis of the Leafony project, a 2 cm square electronic board/electronic module. We call it a leaf because it is small and green. You can easily make your own leaf.

Leafony or the Leafony platform

Leafony is an open hardware and software platform built from leafs. Its ultra-compact size and low power consumption make it easy to create IoT/CPS systems, which is ideal to increase the development efficiency for the future digital transformation. Software development is easy. Of course, you can also develop software outside of the Arduino environment.

Leafony, a word coined from Leaf and Symphony, aims at the harmony between the individual and the whole, and Symphony represents the desire for the Leaf to come together to create great values, just as the sounds of the various instruments work in harmony to create a great piece of music.

The technical information on Leafony is basically free to use for commercial purposes. You can find more information about the license in the License section. User-specific leafs are sold by many companies, individuals, etc., under the guise of being Leafony bus compliant, and we encourage such activities. However, since Leafony is a registered trademark, we ask that you refrain from using the Leafony name on the leaf itself to avoid market confusion.

Leafony block

It is an electronic device that is made up of multiple leaves. Normally, stacked leaves form a block, so it is called a leaf block. An electronic device made by combining leaves, even if the structure is flat and spread out, is called a leaf block.

Leafony bus

A common pathway that connects multiple leaves to each other is called a Leafony bus. It defines the electrical and physical specifications for the electrical signal and power connections. A Leafony bus-compliant leaf will be able to communicate with other leaves, but since it depends on the software and so on whether the Leafony platform is completely safe to connect to, Leafony bus-compliance just means that it is possible to connect close to the physical level.

The Leafony bus artwork is copyrighted and published under the CC-BY License, so you can use it for commercial purposes as well as It is free to use as long as you state that it is Leafony compliant. Therefore, you are free to develop and sell your own leafs. However, since Leafony is a registered trademark, you should not label your leaf as Leafony on it itself; a leaf with the label Leafony will show you that the product quality has been verified, and you will avoid confusion.

Leafony connector

Newly developed anisotropic conductive rubber connectors for interconnecting the leaf. It is both a male and female connector. Although it is possible to connect the leaves with solder and other thermal compression techniques, the Leafony connector is more convenient.

LEAFONY SYSTEMS Co., Ltd.

LEAFONY SYSTEMS was the company that manufactured and sold Leafony products with the registered Leafony trademark, based on the research and development by the Trillion Node Engine Project. Leafs bearing the Leafony label had their interoperability verified by the project.

In March 2026, LEAFONY SYSTEMS transferred its entire business to MITDIR Inc.

MITDIR Inc.

MITDIR Inc. acquired the entire business of LEAFONY SYSTEMS Co., Ltd. in March 2026 and currently handles the sales and support of Leafony products. By combining Leafony with its existing IoT and AI technologies, MITDIR provides DX solutions to a broad range of customers and works to promote IoT technology through collaboration with the research community.

Leafony bus-compliant leafs are also sold by other companies and individuals under the “Leafony-compliant” label, and such activities are encouraged. However, the Leafony trademark itself is not used in those product names.

MCU

MCU stands for Microcontroller Unit. It is an IC that runs programs to read sensors and control outputs such as LEDs or motors. It includes a CPU, memory, and input/output functions. A Leafony board carrying an MCU is called an MCU leaf.

MEMS

MEMS stands for Micro-Electro-Mechanical Systems. The term refers to technology and devices that use tiny mechanical structures and electronic circuits. A MEMS microphone converts the movement of a tiny membrane caused by sound into an electrical signal. AI03 MIC&VR&LED includes a MEMS microphone.

PWM

PWM stands for Pulse Width Modulation. A signal switches on and off at a regular interval, while the proportion of time spent on is varied. It can be used to adjust LED brightness or motor output through a motor driver. The proportion of on-time is called the duty cycle.

SPI

SPI stands for Serial Peripheral Interface. It transfers data between a microcontroller and peripheral devices in time with a clock signal. Leafony uses SPI for devices such as microSD cards. Check each leaf’s specifications for the signals used to select a device and the pin assignments.

Trillion-node engine

This is the electronics platform developed by the Trillion Node Engine Project. It is available to the public under the name Leafony, after organizing the hardware and software that are no longer under development.

Trillion-node engine project

The Trillion Node Engine Project is a research and development project commissioned and subsidized by the New Energy and Industrial Technology Development Organization (NEDO).

Trillion-node study-group

It is said that in the future, many IT nodes such as IoT/CPS will be used in society. The purpose of this workshop is to discuss such future and share information. We are using Leafony as a concrete basis for thinking, and we are trying to promote Leafony for the development of IoT/CPS. We also provide a place to connect related companies that have needs and seeds.

UART

UART stands for Universal Asynchronous Receiver/Transmitter. It provides serial communication using TX to transmit and RX to receive data. Both devices need matching settings such as the communication speed. Leafony uses UART between MCU and communication leaves, and for communication with a computer through a USB-to-UART leaf.

Harness

Electrical connections between a Leafony block and the outside world may require some wiring. Such a wiring is called a harness.