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 and is pronounced “I-squared-C” or “I-two-C.” 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. CPS refers to systems that connect physical and digital spaces.

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

A leaf is an electronic board or module, typically about 2 cm square, that forms the basis of Leafony. It is called a leaf because it is small and green. More precisely, a leaf is an electronic board that has a Leafony bus. You can easily create your own original leaves and sell them commercially by labeling them “Leafony compliant.”

Leafony or the Leafony platform

Leafony is an open hardware and software platform built by combining leaves. Its very small size and low power consumption make it suitable for prototyping IoT/CPS systems and improving development efficiency. Leafony also works in the Arduino environment, so you can use the many software resources available online. You can also develop software in environments other than Arduino.

Leafony is a word coined from Leaf and Symphony. It expresses the hope that individual leaves will come together to create new value, just as the sounds of different instruments combine to make music.

Leafony technical information is generally free to use, including for commercial purposes. See the License section for details. Companies and individuals sell their own leaves labeled “Leafony compliant,” and such activities are encouraged. However, Leafony is a registered trademark, so please refrain from including Leafony in product names 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. Its electrical and physical specifications define the signal and power connections. It typically occupies a 20 mm x 5.5 mm area on a leaf. A Leafony bus-compliant leaf can communicate with other leaves, but whether it works with the Leafony platform without problems also depends on the software and other factors. Leafony bus compliance therefore indicates connectivity close to the physical level.

The Leafony bus artwork is copyrighted and published under the CC-BY License. You may use it free of charge, including commercially, by stating “Leafony compliant.” You are therefore free to develop and sell your own leaves. However, Leafony is a registered trademark, so do not label the leaves you make with Leafony itself. A leaf bearing the Leafony label indicates that its product quality has been verified.

Leafony connector

A connector newly developed to interconnect leaves using anisotropic conductive rubber. It serves as both a male and female connector. Leaves can also be connected using techniques such as solder-based thermocompression bonding, but using a Leafony connector is simpler.

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. Leaves 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 works to provide DX solutions and promote IoT technology through collaboration with the research community.

Leafony bus-compliant leaves are also sold by other companies and individuals under the “Leafony compliant” label, and such activities are encouraged. However, Leafony is not included 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

The electronics platform developed by the Trillion Node Engine Project. Hardware and software whose research and development has been completed are organized and released to the public under the name Leafony.

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

Many IT nodes, including IoT/CPS systems, are expected to be used throughout society in the future. The Trillion-node study-group discusses that future and shares information. It uses Leafony as a practical basis for these discussions and works to promote its use to support the development of IoT/CPS. It also provides a place to connect related companies with needs and technologies to offer.

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 wiring. Such wiring is called a harness.