Wiznet makers

Project Overview

This project demonstrates how to control a Mitsubishi Electric inverter using the W55RP20-EVB-Pico board. The setup includes a 200W motor as the load and a fully configured inverter test environment.

About B&B Lab.

Established: January 2018

Capital: 3 million JPY

Focus Areas: IoT device development and service creation, with a current emphasis on smart agriculture.

CEO: Kohei Masaki

Responsible for hardware development.

Experience: Over 10 years at Sony Semiconductor (Kagoshima, Kumamoto, Fukuoka), specializing in image sensor development.

Expertise:

Image processing software (Visual C++, VBA).

CCD/CMOS image sensor evaluation methodologies.

Analog and digital hardware design.

Power conditioner development for wind power (joint project with Kyushu University).

Participation in medical and other tech ventures.

Co-Founder: Shinri Nakamura

Cloud and firmware specialist.

Background as a bartender, radiological technologist, and self-proclaimed hypermedia creator.

LINE API expert.

Motivation – Why Motors?

The presentation starts with the question: "Do you like motors?"
It highlights various applications including drones, micro-robots (micromouse), railway models, and other electric devices.

The idea is to control more powerful motors through IoT/edge devices. For example, a 3-phase 200V, 2.2kW (3HP) motor can be purchased for about 10,000 JPY on Yahoo Auctions.
One target application is driving pumps for smart agriculture or home gardening.

Challenges in IoT Edge Devices

Prototyping with boards like ESP32 or M5Stack is easy, but in industrial or agricultural settings, wired Ethernet is often required due to:

Security policies restricting wireless Wi-Fi in factories.

Signal attenuation of 2.4GHz due to moisture in plants.

While Ethernet expansion via W5500 + ESP32 is possible, PCB design (especially SPI routing and RJ45) can be challenging.
The W55RP20 (RP2040 + W5500 + external flash as a single SiP) offers a low-cost and low-complexity wired Ethernet solution.

W55RP20 Features & Development

Combines RP2040 MCU, W5500 Ethernet controller, and flash memory in a single package.

Officially supports lwIP-based development but not directly compatible with the Arduino Ethernet library.

A compatibility layer (EthernetCompat.h) is provided.

A sample application implementing Web API-based hardware control (Web UI, GPIO LED control, voltage monitoring, and user-defined functions) is available on GitHub.

Inverter Hardware Control

Target Device: Mitsubishi FREQROL-E700 series inverter (RS485 communication).

RS485 interface enables external control (via RJ45 connector).

An RS485 transceiver was connected to the W55RP20-EVB-Pico using UART + DE (Data Enable).

Most RS485 transceivers operate at 5V, so care must be taken when interfacing with 3.3V MCUs (e.g., voltage division).

The inverter’s parameter unit provides 5V output, which is not officially recommended for RS485, but tests confirmed stable operation at up to 150mA.

When the W55RP20 board was connected, Ethernet operation consumed approximately 140mA, which was sufficiently supplied by the inverter’s built-in power.

Firmware Control

Mitsubishi’s official manual is 334 pages long, and the sample code is outdated.

By utilizing ChatGPT, the RS485 control code was rewritten in Arduino style.

Implemented AT command parsing, multi-threaded queue-based processing, and real-time motor control with status monitoring via Web UI (200ms refresh).

Control code and Web UI examples are published on GitHub:
https://github.com/Unicorn556/WebServerMain_inv

Peripheral Setup & Demonstration

The inverter requires a 3-phase 200V input. For 100V sources, a step-up transformer is used to reach 200V.

A live demo successfully ran the motor using this setup.

Summary

WIZnet W55RP20 has proven to be a highly practical wired Ethernet solution for edge devices.

By combining W55RP20-EVB-Pico with a Web UI, Arduino-based wired Ethernet communication is feasible.

The project demonstrated reliable control of a Mitsubishi inverter via RS485.

Announcements

Upcoming Event: August 2-3, 2025 – Fukuoka Makers Event.

Planned demo: Automatic irrigation system and projects leveraging AITRIOS.