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Femto is Mirek Folejewski’s 12×12 mm module built around Raspberry Pi’s RP2040 microcontroller. It connects all 30 GPIO pins and includes QSPI flash, a 12 MHz oscillator, and a power LED on a four-layer board. The project also provides a solder frame and a tester, plus design and manufacturing files for people who want to build or adapt it.
What is the Femto RP2040 module?
Femto is an open-hardware project designed to make a fully functional RP2040 module as small as possible. Its 12×12 mm, stamp-like PCB carries the microcontroller and supporting parts; the compact module is not the same thing as a conventional development board with large headers and convenient built-in access to every signal. The project repository documents the module, its solder frame, and its tester.
The RP2040 is a dual-core Arm Cortex-M0+ microcontroller. CNX Software reports a maximum clock of 133 MHz and 264 kB of SRAM for the chip. Those are RP2040 specifications, not a performance benchmark of Femto. CNX Software’s 2022 report also describes Femto variants with 4–64 Mbit of onboard flash.
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| Feature | Femto details |
|---|---|
| Board footprint | 12×12 mm, according to the project repository. |
| Microcontroller | Raspberry Pi RP2040. |
| GPIO | All 30 GPIO pins are connected; reset and BOOTSEL signals are exposed through the frame. |
| Flash | Onboard QSPI flash; CNX Software reports 4–64 Mbit across the variants it describes in 2022. |
| Other components | 12 MHz oscillator, decoupling components, and power LED. |
| PCB | Four layers. |
The repository gives approximate comparison dimensions of 51×21 mm for Raspberry Pi Pico and 25×25 mm for Solder Party’s RP2040 Stamp. These are board-footprint comparisons, not claims that the boards have identical connectors, layouts, or ease of use.
#1 Best Overall
- The Raspberry Pi Pico is a beginner-friendly microcontroller board that uses MicroPython to give you a taste of the Internet of Things and microcontrollers. The RP2040 is a well-designed microprocessor that can be utilized in almost any Internet of Things project. It has enough power to complete the task quickly.
- 【Raspberry Pi RP2040 Microcontroller】Raspberry Pi Pico features Dual-core ARM Cortex M0+ processor, flexible clock running up to 133 MHz. With 264KB of SRAM, and 2MB of on-board Flash memory.Supports up to 16 MB of off chip flash memory via a dedicated QSPI bus
- 【Multiple Software Support】Pico has rich and complete software support, it comes with a complete Rasberry Pi official C/C++ SDK, Micropython SDK.The programming and burning of Pico need to be carried out on the computer. Supported operating systems and computers include:Raspberry Pie with Raspberry Pi OS,Other platforms equipped with Debian based Linux system Computer with MacOS, Computers with Windows, etc.
- 【Rich Hardware Interface】Raspberry Pi Pico has 30 GPIO pins, 4 pins for analog signal input and 26 × multi-function GPIO pins, 2 × SPI, 2 × I2C, 2 × UART, 3 × 12-bit ADC, 16 × controllable PWM channels.USB 1.1 supported by host and device, The installation mode can be flexibly selected by users to facilitate welding with other development boards.
- 【Build Project in Tiny Size】Only 2.1cm*5.1cm ( as small as your thumb). Pico has been designed to use either soldered 0.1" pin-headers or can be used as a surface-mountable 'module'.
What the solder frame and tester are for
The project separates the tiny module from the hardware that makes it easier to handle and verify. A solder frame provides a more usable way to access the module’s I/O. That arrangement is useful when minimizing the module’s footprint matters, but it means a builder should plan for a frame or a custom carrier rather than expect the bare 12×12 mm board to behave like a breadboard-ready development board.
The Femto Tester is a dedicated test fixture. Hackster reports that it brings GPIO pins to onboard LEDs and provides USB Type-C for power and data, along with separate BOOTSEL and reset buttons. Hackster’s project coverage describes the tester’s features.
Rank #2
- DUAL-CORE PERFORMANCE & MEMORY: Features the RP2040 microcontroller chip with a dual-core ARM Cortex M0+ processor running at a flexible clock speed up to 133 MHz. Equipped with 264KB of on-chip SRAM and 2MB of on-board Flash memory, providing ample space for complex code and data storage. Includes an on-chip accelerated floating point library for demanding calculations.
- VERSATILE I/O & PERIPHERALS: Provides access to 29 GPIO pins from the RP2040 chip (20 accessible via pin headers, others via soldering). Features a rich set of peripherals including 2x SPI, 2x I2C, 2x UART, 4x 12-bit ADC, and 16 controlled PWM channels. Supports USB1.1 host and device modes for flexible connectivity and communication.
- CUSTOM PERIPHERALS & POWER MODES: Includes 8 programmable I/O (PIO) state machines, allowing for the creation of custom peripheral support beyond standard hardware. Supports low-power sleep and hibernation modes, making it suitable for battery-powered applications. Programming is simplified with drag-and-drop file transfer via USB mass storage recognition.
- COMPACT FORM & EASY INTEGRATION: Features a stamp hole design allowing the board to be directly soldered onto a user-designed backplane for compact and robust integration into custom projects. Includes an accurate on-chip clock, timer, and a temperature sensor. The pins arrive unsoldered, offering flexibility for either direct mounting or use with the included pin headers.
- COMPLETE 6-PACK SET & SUPPORT: Includes 6 x RP2040-Zero Microcontroller Boards and 6 x Pin Header Sets. Digital documentation and technical support for setup, programming, and troubleshooting are available through our store customer service.
How to test Femto’s GPIO pins
The repository includes a Python test script for checking the module with the Femto Tester through the Thonny IDE. Use the project’s own instructions and script for the exact test procedure; the available description establishes the toolchain and fixture, but does not specify a universal pin-by-pin procedure here.
- Connect the Femto module to the tester as described in the project documentation.
- Open the repository’s Python test script in Thonny and follow the project’s directions for running it.
- Use the tester’s GPIO LEDs and its BOOTSEL and reset controls as directed by the test procedure to check the module.
Where to find the Femto design and manufacturing files
The Femto GitHub repository publishes design and production materials, including KiCad and Altium sources, Gerber files, a bill of materials (BOM), pick-and-place data, and assembly files. These are the useful starting points for adapting the design or arranging PCB fabrication and assembly. The repository identifies JLCPCB in connection with production files; that does not establish a current retail source for assembled modules.
Rank #3
- DUAL-CORE PERFORMANCE & MEMORY: Features the RP2040 microcontroller chip with a dual-core ARM Cortex M0+ processor running at a flexible clock speed up to 133 MHz. Equipped with 264KB of on-chip SRAM and 2MB of on-board Flash memory, providing ample space for complex code and data storage. Includes an on-chip accelerated floating point library for demanding calculations.
- VERSATILE I/O & PERIPHERALS: Provides access to 29 GPIO pins from the RP2040 chip (20 accessible via pin headers, others via soldering). Features a rich set of peripherals including 2x SPI, 2x I2C, 2x UART, 4x 12-bit ADC, and 16 controlled PWM channels. Supports USB1.1 host and device modes for flexible connectivity and communication.
- CUSTOM PERIPHERALS & POWER MODES: Includes 8 programmable I/O (PIO) state machines, allowing for the creation of custom peripheral support beyond standard hardware. Supports low-power sleep and hibernation modes, making it suitable for battery-powered applications. Programming is simplified with drag-and-drop file transfer via USB mass storage recognition.
- COMPACT FORM & EASY INTEGRATION: Features a stamp hole design allowing the board to be directly soldered onto a user-designed backplane for compact and robust integration into custom projects. Includes an accurate on-chip clock, timer, and a temperature sensor. The pins arrive unsoldered, offering flexibility for either direct mounting or use with the included pin headers.
- COMPLETE 3-PACK SET & SUPPORT: Includes 3 x RP2040-Zero Microcontroller Boards and 3 x Pin Header Sets. Digital documentation and technical support for setup, programming, and troubleshooting are available through our store customer service.
Is Femto open source, and what license applies?
Femto is documented as open-source hardware and links to its Open Source Hardware Association (OSHWA) certification. The OSHWA registry lists version v1 under UID PL000009, certified September 7, 2022. Its recorded licenses are CERN-OHL-1.2 for hardware and CC BY-SA for documentation; the registry lists no software license. Check the project and registry terms when reusing specific files or code, since the hardware and documentation licenses do not by themselves state a software license.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can you buy a preassembled Femto module?
The project repository provides fabrication and assembly files, but it does not establish a current retailer, price, or stock status for ready-made modules. Verify any seller’s current listing before relying on preassembled hardware being available. If you want to build a Femto-style board, Raspberry Pi’s RP2040 documentation and datasheet resources are the official reference for the microcontroller at its center.
Quick Recap
Best Value
- Support C/C++, MicroPython, complete SDK, open source materials tutorial, easy to use, can be quickly embedded in applications
- Dual-core Arm Cortex M0+ processor, flexible clock running up to 133 MHz
- 264KB of SRAM, and 2MB of on-board Flash memory;USB-C connector, keeps it up to date, easier to use
- Castellated module allows soldering direct to carrier boards; USB 1.1 with device and host support
- Low-power sleep and dormant modes; Drag-and-drop programming using mass storage over USB
Rank #4
- DUAL-CORE PERFORMANCE & MEMORY: Features the RP2040 microcontroller chip with a dual-core ARM Cortex M0+ processor running at a flexible clock speed up to 133 MHz. Equipped with 264KB of on-chip SRAM and 2MB of on-board Flash memory, providing ample space for complex code and data storage. Includes an on-chip accelerated floating point library for demanding calculations.
- VERSATILE I/O & PERIPHERALS: Provides access to 29 GPIO pins from the RP2040 chip (20 accessible via pin headers, others via soldering). Features a rich set of peripherals including 2x SPI, 2x I2C, 2x UART, 4x 12-bit ADC, and 16 controlled PWM channels. Supports USB1.1 host and device modes for flexible connectivity and communication.
- CUSTOM PERIPHERALS & POWER MODES: Includes 8 programmable I/O (PIO) state machines, allowing for the creation of custom peripheral support beyond standard hardware. Supports low-power sleep and hibernation modes, making it suitable for battery-powered applications. Programming is simplified with drag-and-drop file transfer via USB mass storage recognition.
- COMPACT FORM & EASY INTEGRATION: Features a stamp hole design allowing the board to be directly soldered onto a user-designed backplane for compact and robust integration into custom projects. Includes an accurate on-chip clock, timer, and a temperature sensor. The pins arrive unsoldered, offering flexibility for either direct mounting or use with the included pin headers.
- COMPLETE 12-PACK SET & SUPPORT: Includes 12 x RP2040-Zero Microcontroller Boards and 12 x Pin Header Sets. Digital documentation and technical support for setup, programming, and troubleshooting are available through our store customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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