Comu Is a $6 RISC-V Board That Hides in a USB Port

Smaller Than a microSD Card, and It Disappears Into the Port

Icy Electronics has released Comu, a RISC-V development board that measures 13 x 9.4mm — slightly smaller than a microSD card — and is shaped to sit entirely inside a standard USB-A port. It sells for $5.99 on Tindie, dropping to as low as $3.59 per board in quantity.

• WCH CH32V203 RISC-V MCU running at 144MHz
• 13 x 9.4mm footprint, small enough to vanish inside a USB-A socket
• Two white LEDs, four capacitive touch buttons, six GPIOs on exposed test pads
• $5.99 single unit, down to $3.59 each at volume

The CH32V203 is a familiar part to anyone who follows budget RISC-V silicon. What is new here is the packaging: the entire board is the USB connector, so a finished project can be plugged in and effectively hidden. That opens the door to permanently installed peripherals, low-profile dongles, and the kind of always-attached utility device that a full-size dev board makes awkward.

What Can You Actually Build With Six GPIOs?

Comu is aimed squarely at bare-metal work rather than general-purpose computing. Icy Electronics calls out custom USB HID projects and USB packet experimentation as the primary use cases, and both make sense given the form factor. Four capacitive touch buttons on a board this size means a macro pad, a hardware shortcut key, or a presence-detection widget can be built without adding a single external component.

The six GPIOs come out on test pads rather than headers, which is the honest trade for a board this size. You are soldering wires, not plugging in a ribbon cable. For a permanently installed device that is usually fine, and it keeps the profile flat enough to fit the port.

The board ships with a custom 2KB USB bootloader, leaving roughly 28KB of boot flash for user applications. That is a real constraint and worth planning around before you commit, but it is generous for HID work and USB protocol experiments.

Toolchain Support Is Better Than the Price Suggests

The CH32V203 can be programmed several ways: Rust through the ch32-hal crate, the Arduino IDE via arduino_core_ch32, or WCH's own HAL inside MounRiver Studio. The board also works well with the ch32fun project, which has become the go-to lightweight option for bare-metal C and C++ on WCH parts.

Icy Electronics has open-sourced the whole design. KiCad hardware files, the custom bootloader, and several example programs are all published on the project's GitHub repository, which means the board doubles as a reference design if you want to fold the same idea into a larger product.

How It Compares to Other Cheap RISC-V Boards

The budget RISC-V shelf is crowded now. We looked at Waveshare's ESP32-C6-Zero-B with 5V to 36V input for industrial jobs, and Banana Pi's $21 BPI-VP10 servo controller for robotics. Those boards win on connectivity and I/O count. Comu wins on exactly one axis — physical size — and it wins decisively.

If you are choosing between low-power microcontroller families for a new project, our low-power wireless MCU guide covers the tradeoffs across nRF54L, ESP32, and RP2350 parts. Comu sits outside that comparison because it has no radio at all, and that is the point: it is a wired USB device that happens to have a RISC-V core inside.

At six dollars, with open hardware files and a fully documented bootloader, it is the kind of single-board computer accessory that costs less than the shipping. More compact hardware finds lives in our mini computers coverage.

Sources: CNX Software — August 10, 2026; LinuxGizmos — August 2026.