Romu RP2354A Board: A $40 Raspberry Pi Chip in a USB Stick

The Romu RP2354A board might be the smallest way yet to get a Raspberry Pi microcontroller into your projects. Launched on Crowd Supply by maker Bitmerse, Romu is a fingernail-sized board, just 15.5 x 12 mm, that plugs directly into a USB Type-A port like a nano flash drive. Inside is the Raspberry Pi RP2354A, and the board ships with MicroPython ready to go, making it an inexpensive way to build custom security keys, macro buttons or MIDI controllers.

• Chip: Raspberry Pi RP2354A with dual Arm Cortex-M33 and dual Hazard3 RISC-V cores at 150 MHz, 520 KB SRAM and 2 MB in-package flash.
• Size: 15.5 x 12 x 1.65 mm, with a USB 2.0 Full-Speed Type-A connector and no GPIO pins.
• Price: $40 for one board, $90 for a 3-pack, or $65 with the programming and debugging jig.
• Shipping: expected to start at the end of April 2027, according to CNX Software.

What Is the RP2354A?

The RP2354A is a version of the Raspberry Pi RP2350 microcontroller with 2 MB of flash stacked inside the chip package. That matters for a board this tiny: there is no room for a separate flash chip, so the stacked memory is what makes the whole design possible.

Like the RP2350, it carries two Arm Cortex-M33 cores and two RISC-V Hazard3 cores, and you choose which pair to run in software. The Arm cores bring TrustZone and secure boot, which are exactly the features you want in a device that stores login credentials. If you have used other RP2354-based boards, the programming model will feel familiar.

What Can You Build With Romu?

Because Romu has no GPIO pins, it is designed around one thing: being a smart USB device. The board includes a capacitive touch button, a programmable RGB LED and a boot button, and Bitmerse's demo firmware shows off a few ideas:

• Security key: a FIDO2/U2F implementation for passwordless logins.
• Macro pad: one-touch shortcuts that type commands or launch apps.
• USB MIDI controller: a tap-to-trigger controller for music software.
• Custom HID devices: anything that looks like a keyboard or mouse to a computer.

MicroPython comes preinstalled, and LinuxGizmos notes you can program it from the Thonny IDE without an external programmer. Example scripts on GitHub include a small dino game and a website-launcher demo.

Do You Need the Programming Jig?

For most MicroPython users, no. The optional $65 bundle adds a jig with pogo-pin contacts that clamp onto Romu's test points, so you never need to solder headers onto a board this small. It connects over USB-C and exposes a standard 20-pin JTAG connector for SWD debugging plus UART access. If you plan to write C firmware or debug low-level code, it is a worthwhile add-on.

Open Hardware and Campaign Details

Bitmerse describes Romu as open hardware, with schematics, PCB files, the bill of materials and 3D-printable enclosure files due on GitHub before shipping. LinuxGizmos reports that a small test batch has already been built with Elecrow, which is expected to handle production. The Crowd Supply campaign has a $5,000 goal, with shipping add-ons of $8 to the US and $18 elsewhere.

For a $40 board, Romu packs a lot of possibility into a very small space. It is a neat reminder that the Raspberry Pi silicon ecosystem now stretches from desktop computers all the way down to something you could lose in a coat pocket. For more boards like this, see our mini computers coverage.

Sources: CNX Software, Romu tiny Raspberry Pi RP2354A USB board — October 14, 2026; LinuxGizmos, Coin-sized Romu packs Raspberry Pi RP2354A into USB Type-A form factor — October 13, 2026.