This page explains how to set up a serial terminal emulator to operate the R2P2 from a PC.

Required Preparation

A serial terminal emulator is required for communication with R2P2. Please follow the setup instructions below according to your operating system.

Windows

Installing Tera Term

We recommend Tera Term. It’s free, user-friendly, and ideal for serial communication on Windows.

  1. Download from the Tera Term official website
  2. Run the installer to complete setup

Linux

Installing GTKTerm

We recommend GTKTerm. It’s a lightweight, GUI-based serial terminal.

Ubuntu/Debian-based systems

sudo apt update
sudo apt install gtkterm

CentOS/RHEL/Fedora-based systems

# Fedora
sudo dnf install gtkterm

# CentOS/RHEL (requires EPEL repository)
sudo yum install epel-release
sudo yum install gtkterm

macOS

Implementing a terminal emulator seems to be no easy task, as it involves dealing with escape sequences, timing issues, and all sorts of edge cases that have become complicated due to historical reasons. Unfortunately, we don’t know if there are any serial terminal emulators for macOS comparable to Tera Term or GTKTerm.

So far, you can choose from the following options:

Option 1: screen (Simple method)

Using the screen command.

Note: The screen command may cause display issues with the PicoRuby shell (R2P2), such as garbled text or formatting problems.

Installation

# Using Homebrew
brew install screen

# Using MacPorts
sudo port install screen

In addition to screen, you may also be able to use minicom, picocom, CoolTerm, or PuTTY.

Actually, the author of PicoRuby doesn’t have a Mac, so we can’t decide which one is the best.

We recommend this option for a more stable environment.

  1. Create a virtual machine using VirtualBox or VMware
  2. Install Ubuntu Desktop
  3. Install GTKTerm within the virtual environment: 
    sudo apt update
sudo apt install gtkterm

Note: When using a virtual environment, you need to configure USB serial device passthrough to the virtual machine.

Serial Port Connection Methods

Tera Term (Windows)

  1. Launch Tera Term
  2. In the “New Connection” dialog, select “Serial”
  3. Choose the port number (usually COM3, COM4, etc.)
  4. Click “OK”
  5. Set the following in Menu → “Setup” → “Serial port”:
    • Baud rate: 115200
    • Data bits: 8
    • Parity: None
    • Stop bits: 1
    • Flow control: None
  6. Set line ending in Menu → “Setup” → “Terminal”:
    • New-line: Receive: LF, Transmit: LF

GTKTerm (Linux/Virtual Ubuntu)

  1. Launch GTKTerm
  2. Configure in Menu → “Configuration” → “Port”:
    • Port: /dev/ttyUSB0 or /dev/ttyACM0 (depending on device)
    • Baud Rate: 115200
    • Parity: None
    • Bits: 8
    • Stopbits: 1
    • Flow control: None
  3. Configure line endings in Menu → “Configuration” → “CR LF auto”:
    • Enable LF auto (to handle line endings properly)
  4. Click “OK” to connect

screen (macOS)

  1. Check devices: 
    ls /dev/cu.*
  2. Connect with screen: 
    screen /dev/cu.usbserial-XXXXXX 115200

    (Replace XXXXXX with the actual device name)

  3. Configure line endings by pressing Ctrl+A followed by : and enter: 
    crlf off
  4. To exit, press Ctrl+A followed by K, then confirm with y

Troubleshooting

Device not recognized

  • Windows: Check COM ports in Device Manager
  • Linux: Check USB device recognition with dmesg | tail
  • macOS: Check devices with ls /dev/cu.*

Permission errors (Linux)

Add user to dialout group:

sudo usermod -a -G dialout $USER

Logout and login required after this setting.

For Workshop Participants: What to Bring on the Day

  • Laptop (with setup completed as above)
    • IMPORTANT: If your laptop is configured to prohibit writing to USB memory devices, likely due to your company’s security policy, it won’t work. Please check in advance.
  • USB Cable
    • Microcontroller side: Micro-B (Raspberry Pi Pico at EuRuKo 2024 and 2025) or USB-C (M5Stack at mruby Girls Matsue 2025)
    • PC side: Compatible with your laptop (Type-A, Type-C, etc.)
    • Required: Data communication capable (charging-only cables won’t work)

    While the organizers will also provide USB cables, we recommend bringing your own for peace of mind. Many recent laptops have only Type-C ports, so please bring appropriate adapter cables or hubs.

  • Glasses: Workshop will be detailed work, so bring glasses if you are not confident in your eyesight
  • Tweezers: Not required, but for handling small components, they will be very helpful

Questions & Support

If you encounter any issues during setup, please let us know before the workshop begins. We’ll solve it together!

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