Source: https://mokxi.com/boards/rp2040-zero Updated: 2026-10-26 Board # Waveshare RP2040-Zero simulator, the Pico’s chip on a tiny board The RP2040-Zero is the Pico’s RP2040, a Cortex-M0+, on a board 23.5 by 18 mm with twenty-three pins named by GPIO and a NeoPixel on GP16. There is no plain LED. Mokxi runs the chip and the NeoPixel, and this page says what the model leaves out. Start building free - 6 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 GP0 to GP15 and GP26 to GP29, with the silkscreen numbers as the GPIO numbers ADC A0 to A3, on GP26 to GP29, ten bits against 3.3 V by default PWM On any pin The NeoPixel A WS2812 on GP16, so Adafruit_NeoPixel works UART0 and UART1 Serial wired to the serial monitor, and Serial2 on GP8 and GP9 ### Not modeled - The nine solder pads on the back, GP17 to GP25, and the power LED. - RESET and BOOT as pins. They are buttons, with no pin. - A plain user LED: the board has none, so there is no LED_BUILTIN. - 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 RP2040-Zero Each has its own page with the circuit running, the code and a parts list. - RP2040-Zero NeoPixel Beginner - RP2040-Zero 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 GP4 (SDA) and GP5 (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 RP2040-Zero pinout: every GPIO and the NeoPixel ## Questions Is it free? Yes. Every board and every part is on the free plan, with no account needed. Why does Blink not compile? Because the board has no plain LED, so LED_BUILTIN is not defined. Wire an LED to a pin, or color the NeoPixel on GP16; the built-in Blink uses GP0. Can I push it into a breadboard? Not safely. Its five bottom pins sit in one column, so GP9 and GP10 land in the same strip and short together, in Mokxi as on the bench. Keep it beside the breadboard and use jumpers, as the starter does. Does Adafruit_NeoPixel work? Yes. The NeoPixel is a WS2812 model of its own on GP16. Use PIN_NEOPIXEL as the pin and NEO_GRB + NEO_KHZ800 as the type. 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