Live per-platform CI status and supported-board reference for fbuild.
Arduino AVR Platform - Fully Supported
- Arduino Uno (atmega328p, 16MHz) - Fully tested
- Arduino Leonardo (atmega32u4, 16MHz) - Supported
- ATmega8A (atmega8a, 16MHz) - Supported
- ATtiny85 - Supported
- ATtiny88 - Supported
- ATtiny4313 - Supported
About the AVR Family
The Atmel AVR family is the 8-bit microcontroller architecture that launched the Arduino revolution. Originally designed by Atmel (now Microchip Technology) in 1996, these chips became the backbone of the maker movement when Arduino adopted the ATmega328P for the Arduino Uno in 2010. AVR microcontrollers are known for their simplicity, extensive community support, and massive library ecosystem. They remain the go-to choice for learning embedded development, simple I/O projects, and LED control.
| Feature | ATmega328P (Uno) | ATmega32U4 (Leonardo) |
|---|---|---|
| Architecture | 8-bit AVR | 8-bit AVR |
| Clock Speed | 16 MHz | 16 MHz |
| Flash Memory | 32 KB | 32 KB |
| SRAM | 2 KB | 2.5 KB |
| EEPROM | 1 KB | 1 KB |
| Digital I/O Pins | 14 | 20 |
| Analog Inputs | 6 | 12 |
| Native USB | No | Yes |
| Operating Voltage | 5V | 5V |
| Release Year | ~2008 (Uno: 2010) | ~2012 |
| Typical Cost | ~$3–5 | ~$4–6 |
Best for: Beginner projects, LED control, basic sensor reading, learning embedded development, prototyping simple circuits.
ESP8266 Platform - Supported
- ESP8266 (esp8266) - Supported
About the ESP8266 Family
The ESP8266 was a game-changer when Espressif Systems released it in 2014. Originally marketed as a cheap WiFi-to-serial bridge (~$2), the community quickly discovered its full potential as a standalone WiFi-capable microcontroller. It single-handedly kicked off the affordable IoT revolution, making WiFi connectivity accessible for hobbyist and commercial projects alike. While largely superseded by the ESP32 family, the ESP8266 remains popular for simple WiFi applications due to its low cost and mature ecosystem.
| Feature | ESP8266 |
|---|---|
| Architecture | 32-bit Tensilica Xtensa LX106 |
| Clock Speed | 80 MHz (160 MHz boost) |
| Flash Memory | 4 MB (typical) |
| SRAM | 80 KB (user-accessible) |
| WiFi | 802.11 b/g/n (2.4 GHz) |
| Bluetooth | No |
| GPIO Pins | 17 (limited usable) |
| ADC | 1 (10-bit) |
| Operating Voltage | 3.3V |
| Release Year | 2014 |
| Typical Cost | ~$1–3 |
Best for: Simple IoT sensors, WiFi-connected projects, home automation nodes, weather stations, cost-sensitive WiFi applications.
ESP32 Platform - Supported
- ESP32 Dev (esp32dev) - Supported
- ESP32-S2 - Supported
- ESP32-S3 (esp32-s3-devkitc-1) - Supported
- ESP32-C2 - Supported (v0.1.0+)
- ESP32-C3 (esp32-c3-devkitm-1) - Supported
- ESP32-C5 - Supported
- ESP32-C6 (esp32c6-devkit) - Supported
- ESP32-H2 - Supported
- ESP32-P4 - Supported
About the ESP32 Family
The ESP32 is Espressif Systems' flagship family of wireless SoCs and the dominant platform for IoT development. The original ESP32 launched in 2016 as the successor to the ESP8266, adding dual-core processing, Bluetooth, and significantly more memory. Since then, Espressif has expanded the family with specialized variants: the S-series for AI and USB, the C-series using RISC-V cores for cost optimization and WiFi 6, the H-series for Thread/Zigbee mesh networking, and the P-series for high-performance edge computing. Together they cover everything from $0.50 disposable sensors to multimedia edge devices.
| Feature | ESP32 | ESP32-S2 | ESP32-S3 | ESP32-C2 | ESP32-C3 | ESP32-C5 | ESP32-C6 | ESP32-H2 | ESP32-P4 |
|---|---|---|---|---|---|---|---|---|---|
| Architecture | Xtensa LX6 | Xtensa LX7 | Xtensa LX7 | RISC-V | RISC-V | RISC-V | RISC-V | RISC-V | RISC-V |
| Cores | 2 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 2 |
| Clock (MHz) | 240 | 240 | 240 | 120 | 160 | 240 | 160 | 96 | 400 |
| SRAM | 520 KB | 320 KB | 512 KB | 272 KB | 400 KB | 400 KB | 512 KB | 320 KB | 768 KB |
| Flash (typical) | 4 MB | 4 MB | 8 MB | 4 MB | 4 MB | 4 MB | 4 MB | 4 MB | 16 MB |
| WiFi | 2.4 GHz | 2.4 GHz | 2.4 GHz | 2.4 GHz | 2.4 GHz | 2.4+5 GHz (WiFi 6) | 2.4 GHz (WiFi 6) | No | No |
| Bluetooth | BT 4.2 + BLE | No | BLE 5.0 | BLE 5.0 | BLE 5.0 | BLE 5.0 | BLE 5.0 | BLE 5.0 | No |
| 802.15.4 (Thread/Zigbee) | No | No | No | No | No | Yes | Yes | Yes | No |
| USB OTG | No | Yes | Yes | No | No | No | No | No | Yes |
| AI Acceleration | No | No | Yes (vector) | No | No | No | No | No | Yes |
| Release Year | 2016 | 2020 | 2021 | 2022 | 2021 | 2024 | 2023 | 2023 | 2024 |
| Typical Cost | ~$2–4 | ~$2–3 | ~$3–5 | ~$0.50–1 | ~$1–2 | ~$2–3 | ~$2–3 | ~$2–3 | ~$5–8 |
Best for:
- ESP32: General IoT, WiFi+BT projects, audio, displays
- ESP32-S2/S3: USB devices, camera/display applications, AI at the edge (S3)
- ESP32-C2/C3: Cost-optimized IoT, simple WiFi/BLE sensors, high-volume products
- ESP32-C5/C6: WiFi 6, smart home with Thread/Zigbee/Matter support
- ESP32-H2: Thread/Zigbee mesh networking, Matter border routers, low-power sensors
- ESP32-P4: High-performance edge computing, multimedia, display-intensive applications
CH32V (RISC-V) Platform - Supported
- CH32V003 - Supported
About the CH32V Family
The CH32V series from WCH (Nanjing Qinheng Microelectronics) represents the new wave of ultra-low-cost RISC-V microcontrollers from China. The CH32V003, launched around 2022–2023, made headlines as a ~$0.10 microcontroller that could genuinely replace legacy 8-bit chips like the ATtiny in cost-sensitive designs. Running a 32-bit RISC-V core at 48 MHz with more memory than an ATtiny, the CH32V003 offers modern 32-bit capabilities at 8-bit prices. WCH's broader CH32V lineup spans from the tiny V003 up to the V307 with Ethernet and USB, positioning the family as a serious alternative for everything from disposable sensors to industrial control.
| Feature | CH32V003 |
|---|---|
| Architecture | 32-bit RISC-V (RV32EC) |
| Clock Speed | 48 MHz |
| Flash Memory | 16 KB |
| SRAM | 2 KB |
| GPIO Pins | 18 |
| ADC | 8 channels (10-bit) |
| UART | 1 |
| SPI | 1 |
| I2C | 1 |
| Timers | 2 |
| Operating Voltage | 3.3V / 5V tolerant |
| Package Options | SOP-8, SOP-16, QFN-20 |
| Release Year | 2022–2023 |
| Typical Cost | ~$0.10–0.20 |
Best for: Ultra-low-cost applications, replacing ATtiny/PIC in production, high-volume consumer electronics, disposable/embedded sensors, cost-sensitive LED drivers.
Teensy Platform - Supported
- Teensy 4.1 - Supported
- Teensy 4.0 - Supported
- Teensy 3.6 - Supported
- Teensy 3.5 - Supported
- Teensy 3.2 - Supported
- Teensy 3.1 - Supported
- Teensy 3.0 - Supported
- Teensy LC - Supported
About the Teensy Family
Teensy is a family of high-performance ARM-based development boards created by PJRC (Paul Stoffregen). Since 2011, Teensy boards have been the go-to choice for projects requiring serious processing power in a small form factor, particularly in audio, USB, and real-time applications. The Teensy 4.x series, powered by the NXP i.MX RT1062 Cortex-M7 at 600 MHz, was the fastest Arduino-compatible microcontroller board when it launched in 2019. Teensy is known for its exceptional audio library, mature USB stack (supporting MIDI, serial, HID, and more simultaneously), and robust real-time performance.
| Feature | Teensy LC | Teensy 3.6 | Teensy 4.0 | Teensy 4.1 |
|---|---|---|---|---|
| Architecture | ARM Cortex-M0+ | ARM Cortex-M4F | ARM Cortex-M7 | ARM Cortex-M7 |
| Clock Speed | 48 MHz | 180 MHz | 600 MHz | 600 MHz |
| Flash Memory | 62 KB | 1 MB | 2 MB | 8 MB |
| SRAM | 8 KB | 256 KB | 1 MB | 1 MB |
| FPU | No | Single-precision | Double-precision | Double-precision |
| USB | USB 2.0 | USB 2.0 High Speed | USB 2.0 High Speed | USB 2.0 High Speed |
| Ethernet | No | No | No | Yes (10/100) |
| SD Card | No | Built-in SDIO | No | Built-in SDIO |
| Audio | I2S | I2S + DAC | I2S + S/PDIF | I2S + S/PDIF |
| Digital I/O | 27 | 62 | 40 | 55 |
| Analog Inputs | 13 | 25 | 14 | 18 |
| Operating Voltage | 3.3V | 3.3V | 3.3V | 3.3V |
| Release Year | 2015 | 2016 | 2019 | 2020 |
| Typical Cost | ~$12 | ~$30 | ~$24 | ~$32 |
Best for: Audio synthesis and processing, USB MIDI controllers, real-time data acquisition, LED installations requiring high frame rates, flight controllers, robotics, any project demanding maximum processing power with Arduino compatibility.
WASM / WebAssembly Platform - Supported
- Compiles Arduino/FastLED sketches to WebAssembly via Emscripten (
clang-tool-chain-emcc) - Outputs
firmware.js+firmware.wasm - Library dependencies from
lib_depscompiled and linked automatically
About the WASM Platform
WebAssembly (WASM) is not a physical microcontroller but a compilation target that allows Arduino/FastLED sketches to run in web browsers or server-side runtimes. fbuild uses Emscripten's Clang-based toolchain to cross-compile C/C++ Arduino code into portable .wasm binaries. This enables browser-based simulation, testing without hardware, and web-based LED visualizers. FastLED uses this extensively for its web-based examples and testing infrastructure.
| Feature | WASM (Emscripten) |
|---|---|
| Architecture | Stack-based virtual machine |
| Runtime | Browser (V8, SpiderMonkey, etc.) or Node.js |
| Compiler | Clang via Emscripten |
| Output | firmware.js + firmware.wasm |
| Hardware Access | None (simulated) |
| Debugging | Browser DevTools |
| Performance | Near-native speed in browser |
| Use Case | Simulation, testing, web demos |
Best for: Browser-based LED simulators, testing without physical hardware, web demos, CI/CD firmware validation, interactive documentation.
MegaAVR Platform - Supported
- ATtiny1604 - Supported
- ATtiny1616 - Supported
- Arduino Nano Every (ATmega4809) - Supported
About the MegaAVR Family
The MegaAVR (also called AVR Dx / tinyAVR 1-series) is Microchip's modernized AVR architecture. These chips retain the familiar AVR instruction set but add improved peripherals, configurable custom logic (CCL), an event system for peripheral-to-peripheral communication without CPU involvement, and a more flexible clock system. The ATtiny1604/1616 replace older ATtiny chips with more flash, SRAM, and peripherals at similar price points. The ATmega4809 powers the Arduino Nano Every, providing a drop-in upgrade path from the classic Nano.
| Feature | ATtiny1604 | ATtiny1616 | ATmega4809 (Nano Every) |
|---|---|---|---|
| Architecture | 8-bit AVR (tinyAVR 1-series) | 8-bit AVR (tinyAVR 1-series) | 8-bit MegaAVR 0-series |
| Clock Speed | 20 MHz | 20 MHz | 20 MHz |
| Flash Memory | 16 KB | 16 KB | 48 KB |
| SRAM | 1 KB | 2 KB | 6 KB |
| EEPROM | 256 B | 256 B | 256 B |
| GPIO Pins | 12 | 18 | 33 |
| ADC | 10-bit, 8 channels | 10-bit, 12 channels | 10-bit, 8 channels |
| Event System | Yes | Yes | Yes |
| CCL (Custom Logic) | Yes | Yes | Yes |
| Operating Voltage | 1.8–5.5V | 1.8–5.5V | 1.8–5.5V |
| Release Year | ~2018 | ~2018 | ~2019 |
| Typical Cost | ~$0.50–1 | ~$0.60–1 | ~$3–5 (on Nano Every) |
Best for: Modern replacements for classic ATtiny/ATmega projects, low-power sensing, cost-sensitive designs needing more peripherals than classic AVR.
Renesas RA Platform - Supported
- Arduino UNO R4 WiFi (RA4M1) - Supported
About the Renesas RA Family
The Arduino UNO R4 WiFi is Arduino's first board based on a Renesas RA4M1 (ARM Cortex-M4) processor, replacing the classic ATmega328P. Released in 2023, it represents Arduino's move into 32-bit territory for their flagship UNO form factor. The R4 WiFi adds an ESP32-S3 module for WiFi/BLE connectivity and includes a 12x8 LED matrix on-board. It maintains the classic UNO shield-compatible form factor while delivering significantly more processing power and memory.
| Feature | UNO R4 WiFi |
|---|---|
| Architecture | ARM Cortex-M4 (Renesas RA4M1) |
| Clock Speed | 48 MHz |
| Flash Memory | 256 KB |
| SRAM | 32 KB |
| WiFi | 802.11 b/g/n (via ESP32-S3) |
| Bluetooth | BLE 5.0 (via ESP32-S3) |
| USB | USB-C (native USB) |
| LED Matrix | 12x8 on-board |
| Operating Voltage | 5V |
| Release Year | 2023 |
| Typical Cost | ~$28 |
Best for: Upgrading classic UNO projects to 32-bit, WiFi-enabled Arduino projects, educational use with the on-board LED matrix.
STM32 Platform - Supported
- STM32F103C8 (Blue Pill) - Supported
- STM32F103CB (Maple Mini) - Supported
- STM32F103TB (HY TinySTM103T) - Supported
- STM32F411CE (Black Pill) - Supported
- STM32H747XI (Arduino GIGA R1) - Supported
- Nucleo F429ZI - Supported
- Nucleo F439ZI - Supported
About the STM32 Family
STM32 is STMicroelectronics' extensive family of ARM Cortex-M microcontrollers, widely used in industrial, automotive, and consumer applications. The family spans from ultra-low-power Cortex-M0 to high-performance dual-core Cortex-M7+M4 devices. The "Blue Pill" (STM32F103C8) became the gateway drug for many makers transitioning from Arduino to 32-bit ARM, offering 72 MHz Cortex-M3 performance for under $2. The STM32H7 series represents the high end, with the dual-core H747 powering Arduino's GIGA R1 WiFi board.
| Feature | STM32F103 (Blue Pill) | STM32F411CE (Black Pill) | STM32H747XI (GIGA R1) | Nucleo F429ZI |
|---|---|---|---|---|
| Architecture | Cortex-M3 | Cortex-M4F | Cortex-M7 + M4 | Cortex-M4F |
| Clock Speed | 72 MHz | 100 MHz | 480 + 240 MHz | 180 MHz |
| Flash Memory | 64–128 KB | 512 KB | 2 MB | 2 MB |
| SRAM | 20 KB | 128 KB | 1 MB | 256 KB |
| FPU | No | Single-precision | Double-precision | Single-precision |
| USB | USB 2.0 FS | USB 2.0 FS | USB 2.0 HS | USB 2.0 FS/HS |
| Ethernet | No | No | Yes | Yes |
| Camera Interface | No | No | Yes (DCMI) | Yes (DCMI) |
| Release Year | ~2007 | ~2019 | ~2022 | ~2014 |
| Typical Cost | ~$1–2 | ~$3–5 | ~$60 (on GIGA R1) | ~$25 |
Best for: Industrial control, motor driving, USB devices, high-performance embedded applications, prototyping with the Nucleo ecosystem.
Atmel SAM / SAMD Platform - Supported
- Arduino Due (SAM3X8E) - Supported
- SAMD21 (Adafruit Feather M0) - Supported
- SAMD21 (Arduino Zero) - Supported
- SAMD51J (Adafruit Feather M4) - Supported
- SAMD51P (Adafruit Grand Central M4) - Supported
About the SAM / SAMD Family
The Atmel SAM family (now Microchip) covers ARM-based microcontrollers used extensively in the Arduino ecosystem. The SAM3X8E powered the Arduino Due (the first official 32-bit Arduino). The SAMD21 (Cortex-M0+) is the foundation for Arduino Zero, MKR boards, and many Adafruit Feather boards. The SAMD51 (Cortex-M4F) brings significantly more performance with hardware floating point, making it popular for audio processing and complex sensor fusion.
| Feature | SAM3X8E (Due) | SAMD21G18A (Zero/Feather M0) | SAMD51J19A (Feather M4) | SAMD51P20A (Grand Central) |
|---|---|---|---|---|
| Architecture | Cortex-M3 | Cortex-M0+ | Cortex-M4F | Cortex-M4F |
| Clock Speed | 84 MHz | 48 MHz | 120 MHz | 120 MHz |
| Flash Memory | 512 KB | 256 KB | 512 KB | 1 MB |
| SRAM | 96 KB | 32 KB | 192 KB | 256 KB |
| FPU | No | No | Single-precision | Single-precision |
| USB | USB 2.0 HS | USB 2.0 FS | USB 2.0 FS | USB 2.0 FS |
| DAC | 2x 12-bit | 1x 10-bit | 2x 12-bit | 2x 12-bit |
| Release Year | 2012 (Due) | 2015 (Zero) | ~2018 | ~2019 |
| Typical Cost | ~$10–15 | ~$5–20 | ~$15–25 | ~$35–40 |
Best for: Audio processing (SAMD51), USB MIDI/HID devices, complex sensor projects, CircuitPython development, scientific instruments.
RP2040 / RP2350 Platform - Supported
- RP2040 (Raspberry Pi Pico) - Supported
- RP2350 (Raspberry Pi Pico 2) - Supported
About the RP2040 / RP2350 Family
The RP2040 is the Raspberry Pi Foundation's first microcontroller, released in 2021. It broke new ground with its unique PIO (Programmable I/O) state machines — dedicated hardware that can implement arbitrary digital protocols without CPU involvement. This makes it exceptionally good for driving LEDs, implementing custom serial protocols, and bit-banging at high speeds. The RP2350 (2024) doubles down with a faster dual-core Cortex-M33, adds hardware security features, and optionally includes RISC-V cores.
| Feature | RP2040 (Pico) | RP2350 (Pico 2) |
|---|---|---|
| Architecture | Dual Cortex-M0+ | Dual Cortex-M33 (or RISC-V) |
| Clock Speed | 133 MHz | 150 MHz |
| Flash Memory | 2 MB (external) | 4 MB (external) |
| SRAM | 264 KB | 520 KB |
| PIO State Machines | 8 (2 blocks × 4) | 12 (3 blocks × 4) |
| FPU | No | Single-precision |
| USB | USB 1.1 | USB 1.1 |
| Security | None | ARM TrustZone, secure boot |
| ADC | 3x 12-bit | 4x 12-bit |
| Release Year | 2021 | 2024 |
| Typical Cost | ~$4 | ~$5 |
Best for: LED driving (PIO is ideal for WS2812), custom digital protocols, USB devices, educational projects, cost-effective dual-core applications.
Nordic NRF52 Platform - Supported
- nRF52840 DK - Supported
About the Nordic NRF52 Family
The Nordic nRF52 series is the industry standard for Bluetooth Low Energy (BLE) development. The nRF52840 is the flagship, featuring a Cortex-M4F at 64 MHz with 1 MB flash, USB, and support for BLE 5.0, Thread, Zigbee, and 802.15.4. Nordic's SoftDevice BLE stack is considered one of the most reliable and power-efficient in the industry. The nRF52840 DK is the official development kit, while many third-party boards (Adafruit Feather, Seeed XIAO) use the same chip.
| Feature | nRF52840 |
|---|---|
| Architecture | ARM Cortex-M4F |
| Clock Speed | 64 MHz |
| Flash Memory | 1 MB |
| SRAM | 256 KB |
| Bluetooth | BLE 5.0 (Long Range, 2Mbps) |
| 802.15.4 | Yes (Thread, Zigbee) |
| USB | USB 2.0 FS |
| NFC | Yes (tag emulation) |
| Operating Voltage | 1.7–5.5V |
| Release Year | ~2018 |
| Typical Cost | ~$5–10 (chip), ~$40 (DK) |
Best for: BLE peripherals, wireless sensors, wearables, Thread/Zigbee mesh devices, USB+BLE combination devices.
Apollo3 Platform - Supported
- SparkFun RedBoard Artemis ATP - Supported
- SparkFun Thing Plus expLoRaBLE - Supported
About the Apollo3 Family
The Ambiq Apollo3 is an ultra-low-power ARM Cortex-M4F microcontroller designed for battery-powered and always-on applications. Ambiq's patented Subthreshold Power Optimized Technology (SPOT) enables the Apollo3 to run at under 6 µA/MHz — roughly 10x more power-efficient than typical Cortex-M4 chips. SparkFun's Artemis module packages the Apollo3 Blue with an antenna, flash, and support circuitry, making it accessible through Arduino-compatible boards.
| Feature | Apollo3 Blue |
|---|---|
| Architecture | ARM Cortex-M4F |
| Clock Speed | 48 MHz (96 MHz burst) |
| Flash Memory | 1 MB |
| SRAM | 384 KB |
| BLE | BLE 5.0 |
| Power Consumption | ~6 µA/MHz (active) |
| ADC | 14-bit |
| PDM Microphone Interface | Yes |
| Operating Voltage | 1.8–3.6V |
| Release Year | ~2019 |
| Typical Cost | ~$15–25 (on SparkFun boards) |
Best for: Ultra-low-power wearables, battery-powered BLE sensors, always-on voice detection, energy harvesting applications.
Silicon Labs EFM32 Platform - Supported
- MGM240 (SparkFun Thing Plus Matter) - Supported
About the Silicon Labs EFM32 / EFR32 Family
The Silicon Labs EFR32MG24 (MGM240 module) is a Cortex-M33 SoC designed for Matter, Thread, and Zigbee smart home applications. It is one of the first chips purpose-built for the Matter smart home standard, with hardware acceleration for the cryptographic operations Matter requires. The SparkFun Thing Plus Matter board and Arduino Nano Matter both use the MGM240S module, making it easy to prototype Matter-compatible devices with Arduino.
| Feature | EFR32MG24 (MGM240S) |
|---|---|
| Architecture | ARM Cortex-M33 |
| Clock Speed | 78 MHz |
| Flash Memory | 1536 KB |
| SRAM | 256 KB |
| 802.15.4 | Yes (Thread, Zigbee) |
| Bluetooth | BLE 5.3 |
| Security | ARM TrustZone, Secure Vault |
| AI/ML Accelerator | Yes (MVP) |
| Matter Support | Native |
| Operating Voltage | 1.71–3.8V |
| Release Year | ~2023 |
| Typical Cost | ~$25–30 (on SparkFun board) |
Best for: Matter smart home devices, Thread mesh networking, secure IoT endpoints, Zigbee coordinators.
Planned Support:
- Arduino Mega
For the workflow to add or fix a board definition, see the /board-support skill and the scripts under ci/ (board_sources.py, validate_boards.py).