Source: https://mokxi.com/boards/xiao-rp2040 Updated: 2026-10-26 Board # Seeed XIAO RP2040 simulator, the Pico’s chip on a thumbnail The XIAO RP2040 is the Pico’s RP2040, a Cortex-M0+, on a board 21 by 17.5 mm with fourteen pads. Its D0 to D10 are the XIAO family’s numbers, not GPIOs. It has a red, green and blue user LED, each lit LOW, and a NeoPixel that GPIO 11 powers, and both work here as they do on the board. Start building free - 7 peripheral areas modeled - 2 projects ready to run - Real time on your own machine Click to open it in the editor The board is running real firmware right now. Click it to open the circuit in the editor. The model ## What is modeled Taken from the board's own contract document and put in plain words, with what is missing beside it. ### Modeled Core The RP2040’s Cortex-M0+, the Pico model whole GPIO The eleven D pads, with the XIAO’s names defined as GPIO numbers ADC A0 to A3, on D0 to D3, ten bits against 3.3 V by default PWM On any pad The user LED Red on GPIO 17 (LED_BUILTIN), green on 16, blue on 25, each lit when its pin is LOW The NeoPixel A WS2812 on GPIO 12, powered from GPIO 11, so Adafruit_NeoPixel works UART0 Wired to the serial monitor ### Not modeled - The pads on the back: the SWD pair, RUN and the battery pads. The power LED is not modeled either. - RESET and BOOT as pins. They are buttons, with no pin. - The RP2040’s second core, PIO, DMA, its own I2C and SPI blocks (Wire and SPI run in software), the USB controller and the RTC. Start here ## Open one and press Run Each of these opens in the editor exactly as it is drawn here. Projects ## Every built-in project on the XIAO RP2040 Each has its own page with the circuit running, the code and a parts list. - XIAO RP2040 NeoPixel Beginner - XIAO RP2040 blink Beginner Libraries ## Arduino libraries that compile as they are Paste a tutorial that includes one of these and it builds. For any other library, the build names the Mokxi header that does the same job. Servo.h attach, write, writeMicroseconds, read, detach, on any pin Wire.h I2C as a master; Wire.begin() puts it on D4 (SDA) and D5 (SCL) SPI.h transfer and transactions, on the board’s usual SPI pins EEPROM.h read, write, update, get, put and EEPROM[i], kept in 4 KB of RAM, which a reset clears: this board has no EEPROM to write LiquidCrystal_I2C.h the 16x2 LCD behind its I2C backpack Adafruit_GFX.h and Adafruit_SSD1306.h the 128x64 I2C OLED: text, pixels, lines, rectangles, circles, triangles and bitmaps Adafruit_NeoPixel.h WS2812 strips and panels DHT.h the DHT11 and DHT22: temperature, humidity and the heat index, as floats you can print And 15 more, 23 in all: OneWire.h and DallasTemperature.h ; Adafruit_BME280.h, Adafruit_BMP280.h and SparkFunBME280.h ; RTClib.h ; Adafruit_SHT31.h ; Adafruit_PCF8591.h ; Adafruit_ADXL345_U.h ; LedControl.h ; Adafruit_LEDBackpack.h ; Adafruit_TCS34725.h ; Adafruit_SGP30.h ; Adafruit_INA219.h ; Adafruit_ADS1X15.h ; Adafruit_MCP23X17.h ; Bounce2.h ; HX711.h . Learn ## Tutorials that use this board Each one ends in a running circuit, on this same board. - The XIAO RP2040 pinout: D0 to D10, the LEDs and the NeoPixel ## Questions Is it free? Yes. Every board and every part is on the free plan, with no account needed. Is D0 GPIO 0? No. D0 is GPIO 26, and D6 is GPIO 0. A bare number is a GPIO here, so digitalWrite(0, HIGH) drives D6. Use the D names in your sketch; they are defined for this board. Why does my NeoPixel stay dark? Its supply comes from GPIO 11. Drive NEOPIXEL_POWER HIGH in setup() before you send it colors, as Seeed’s examples do. Without that it stays dark here, and on the real board too. Why does the LED light when I write LOW? The three user LEDs are wired from 3.3 V to their pins, so each lights when its pin is LOW. digitalWrite(LED_BUILTIN, LOW) turns the red one on. Also here ## The other boards Every one of these runs today, and every one is free. ESP32-C3-DevKitM-1 A RISC-V chip at 160 MHz, on the real memory map. Open the board page Arduino Uno R3 The classic Arduino, with an ATmega328P running at 16 MHz. Open the board page Arduino Nano The Uno’s chip on a small board that fits a breadboard. Open the board page Arduino Mega 2560 The big Arduino, with 54 digital pins and four serial ports. Open the board page Arduino Leonardo An Uno-shaped board whose chip does its own USB serial. Open the board page ESP32-C6-DevKitC-1 A second RISC-V board, with 31 pins and simulated WiFi. Open the board page ESP32 DevKit V1 The classic ESP32 at 240 MHz, with simulated WiFi. Open the board page ESP32-S3-DevKitC-1 The ESP32-S3 at 240 MHz, with USB serial and an RGB LED. Open the board page All 39 boards ## Try it on your own firmware What you build here runs on the board on your desk, unchanged. Nothing to install and no account needed. Start building free Open the editor