Source: https://mokxi.com/boards/pico Updated: 2026-09-27 Board # Raspberry Pi Pico simulator, RP2040 and all Mokxi models the Raspberry Pi Pico on our own Cortex-M0+ core, running the RP2040 at 125 MHz. SIO GPIO, a microsecond timer with four alarms, UART0 and eight PWM slices use their real addresses. Test finished firmware on the physical board too. Sign up free - 7 peripheral areas modeled - 3 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 listed underneath. Core Cortex-M0+ (ARMv6-M), one core, with the datasheet cycle count of every instruction SIO GPIO Real register offsets on IO_BANK0, PADS_BANK0 and SIO, with pull-ups as the datasheet gives them TIMER A 64-bit microsecond counter with four alarms, which park the core during delay() rather than spinning on it UART0 Paced at the configured baud rate, wired to the serial monitor PWM slices Eight slices, two channels each, so analogWrite works on every GPIO pin Sleep WFI parks the core between events, so an idle sketch costs almost nothing to simulate Memory map The real RP2040 addresses for everything above, so a build is not Mokxi-specific ### Not in the model - The second core. SIO.CPUID reads 0, and there is no way to launch core 1. - PIO and DMA. Neither has a model yet. - The ADC. GP26 to GP28 are plain GPIO here, and ADC_VREF is only a supply pin. - USB, including running Raspberry Pi Pico SDK binaries: those need the bootloader and clock tree, which are not modeled. 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 Pico Each has its own page with the circuit running, the code and a parts list. - Pico button - Pico chaser - Pico arcade button Libraries ## Arduino libraries that compile as they are Paste a tutorial that includes one of these and it builds: each is written for Mokxi, on its own drivers, under the name the tutorials use. 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 DHT.h the DHT11 and DHT22: temperature, humidity and the heat index, as floats you can print OneWire.h and DallasTemperature.h DS18B20 thermometers, any number on one pin, found by the 1-Wire search Adafruit_BME280.h, Adafruit_BMP280.h and SparkFunBME280.h the Bosch pressure sensors: temperature, pressure, humidity and altitude RTClib.h the DS3231 and DS1307 clocks, with DateTime and TimeSpan Adafruit_SHT31.h the SHT31’s temperature and humidity, CRC checked LedControl.h MAX7219 eight-digit displays and 8x8 matrices: digits, characters, rows and single LEDs Adafruit_LEDBackpack.h the HT16K33 four-digit backpack: numbers, raw segments, the colon, brightness and blink Adafruit_TCS34725.h the TCS34725’s red, green, blue and clear counts, lux and color temperature Adafruit_SGP30.h the SGP30’s CO2eq and TVOC, its baseline and humidity compensation Adafruit_INA219.h current, bus voltage and power through the INA219’s shunt Adafruit_ADS1X15.h the ADS1115’s four sixteen-bit inputs, single or differential Adafruit_MCP23X17.h the MCP23017’s sixteen pins, one at a time or a port at once HX711.h the HX711 load cell amplifier: tare, set_scale and get_units, the units as floats you can print Learn ## Tutorials that use this board Each one ends in a running circuit, on this same board. PWM on the Pico: slices, channels and 1 kHz Uno vs ESP32 vs Pico: which to start with ## Questions Is it free? Yes. Every board and every part is on the free plan, with no account needed. Does it run Pico SDK binaries? No. The SDK needs the second-stage bootloader and the clock tree, and neither is modeled. The firmware runtime here is ours, and it is Arduino-shaped. Will my firmware run on a real Pico? Yes, as long as it does not reach for the second core, PIO, DMA or the ADC. The memory map and the register offsets are the real ones. Do I need an account? Only to save projects to the cloud and share them by link. Also here ## The other boards Every one of these runs today, and every one is free. Looking for the shorter introduction? See the Raspberry Pi Pico simulator page. ESP32-C3-DevKitM-1 runs now A RISC-V core at 160 MHz with GPIO, UART, the SYSTIMER, a twelve-bit ADC on GPIO 0 to 4 and LEDC PWM on any pin, on the real memory map. Firmware for the modeled peripherals uses the board’s memory map. The contract also marks register addresses inside the SAR ADC and LEDC that are still unverified. Open the board page Arduino Uno R3 runs now A complete ATmega328P, with three timers in every mode, USART0, the ADC, interrupts and sleep. Blink, serial, a held button and a hardware PWM fade, at 16 MHz and real time. Open the board page Arduino Nano runs now The Uno's ATmega328P on a board 45 by 18 mm, so it pushes into the breadboard instead of standing beside it. Two more analog inputs than an Uno, and the same firmware runs on both. Open the board page Arduino Mega 2560 runs now The big Arduino: fifty-four digital pins, sixteen analog inputs and four serial ports, on the ATmega2560. Everything an Uno sketch knows how to do, with enough pins left over to do it to twelve things at once. Open the board page Arduino Leonardo runs now An Uno-shaped board whose USB goes to the chip itself: Serial is a USB CDC endpoint and Serial1 is pins 0 and 1. The ATmega32U4 with its ten-bit timer, fourteen ADC channels and five external interrupts, at 16 MHz. Open the board page ESP32-C6-DevKitC-1 runs now A second RISC-V board: thirty-one GPIOs, 512 KB of SRAM in one window, UART0, the SYSTIMER, a twelve-bit ADC on GPIO 0 to 6 and LEDC PWM on any pin. The contract says plainly which addresses come from the manual, which are believed rather than verified, and what is not modeled at all. Open the board page ESP32 DevKit V1 runs now The classic ESP32 on an Xtensa LX6 at 240 MHz: the GPIO matrix, UART0, timer group 0, a twelve-bit ADC1 and the eight LEDC PWM channels, on the real memory map. One core where the chip has two, no radio and no FPU. Your own sketch compiles in the tab. Open the board page ESP32-S3-DevKitC-1 runs now The ESP32-S3 on an Xtensa LX7 at 240 MHz: GPIO matrix, UART0, USB serial, ADC1, LEDC PWM and the RMT driving the RGB LED, on the real memory map. One core where the chip has two, no radio and no FPU. Your own sketch compiles in the tab. Open the board page ESP8266 NodeMCU V1.0 runs now The Xtensa LX106 at 80 MHz in the call0 ABI, with D0 to D8 that are not GPIO numbers, two active-low LEDs, and PWM done in software because the chip has none. WiFi uses a simulated network, with no radio or real internet. The ADC is the one block whose registers are this model’s own, because Espressif never published the chip’s. Open the board page Raspberry Pi Pico W runs now The same RP2040 and the same forty pins as the Pico, so the same ELF runs on it. The CYW43439 is not modeled. WiFi uses a simulated network, and the on-board LED is driven through the board runtime rather than GP25. Open the board page Seeed XIAO SAMD21 runs now A thumbnail-sized Cortex-M0+ at 48 MHz: eleven pads, every one of them an analog input, with PWM on ten of them. Serial is the chip’s own USB, modeled as a byte pipe with no stack above it, and Serial1 is a real USART on D6 and D7. Open the board page BBC micro:bit V2 runs now The nRF52833 on our own Cortex-M4 core at 64 MHz, with GPIO, GPIOTE, three TIMERs, RTC0 and UARTE0 on the real register map. The 5x5 LED matrix scanned as the hardware scans it, buttons A and B, the speaker and three rings on the edge connector. Open the board page ATtiny85 runs now A whole microcontroller in an 8-pin DIP, straight into the breadboard: six I/O, two timers, an ADC and a USI. Blink, a button on INT0, a knob on the ADC and a serial port it bit-bangs for itself. Open the board page STM32F411 Black Pill runs now Cortex-M4 with Thumb-2, NVIC and SysTick at 84 MHz, with GPIO, TIM2 to TIM5 and USART1 on the real register map. Blink on PC13, a button, serial and a PWM fade, all at real time. Open the board page STM32 Blue Pill (F103) runs now Cortex-M3 at 72 MHz, with GPIO on the F1’s CRL and CRH, TIM1 to TIM4, USART1 and a twelve-bit ADC. Blink on PC13, a button, serial with a live reading, and a PWM fade, all at real time. Open the board page Arduino Uno R4 Minima runs now Renesas RA4M1, Arm Cortex-M4 at 48 MHz, in an Uno’s shape and on an Uno’s 5 V pins. Modeled: the PFS port block, GPT PWM on the six tilde pins, SCI2 as Serial1 on D0 and D1, and a fourteen-bit ADC that analogRead reads ten bits of. Not modeled: a USB stack (Serial is a byte pipe with no enumeration behind it), the ICU, so there is no attachInterrupt, and the AGT. The contract says plainly which addresses come from the manual and which are believed rather than verified. Open the board page Arduino Pro Mini runs now The Uno’s ATmega328P on the smallest Arduino there is, with no USB on it, in both builds: 5 V at 16 MHz and 3.3 V at 8 MHz. The 3.3 V board really runs at 8 MHz, so a sketch built for 16 MHz keeps half time on it, as it does on the bench. Open the board page Arduino Micro runs now The Leonardo’s ATmega32U4 on a board that pushes into a breadboard, with the L LED on pin 13 and the SPI pins on holes of their own. Serial is the chip’s own USB and Serial1 is pins 0 and 1, and the Leonardo’s programs run on it unchanged. Open the board page SparkFun Pro Micro runs now The ATmega32U4 in a Pro Mini’s footprint with a USB socket on the end, running the Leonardo’s programs. No LED on pin 13: its lamps are RX and TX, lit by pulling their pins low. Open the board page Wemos D1 mini runs now The NodeMCU’s ESP8266 on a board a third the size, with the same D0 to D8 names and only the holes that do something. WiFi on a simulated network, and your own sketch compiles in the tab. Open the board page ESP-01S runs now An ESP8266 with eight pins, four of them GPIO, and a blue LED that lights when its pin is low. Wired with jumpers, because its two rows will not sit in a breadboard. WiFi is simulated. Open the board page Seeed XIAO ESP32-C3 runs now The ESP32-C3 at 160 MHz on the XIAO’s thumbnail outline: fourteen pads, and D0 to D10 that are the XIAO’s numbers, not GPIOs. No user LED to blink, WiFi on a simulated network, and sketches that compile in the tab. Open the board page ESP32-C3 SuperMini runs now The smallest ESP32-C3 board in common use, sixteen pins named by GPIO, at 160 MHz. Its blue LED on GPIO 8 lights when the pin is LOW, the other way around from the DevKit’s. Open the board page Arduino Uno R4 WiFi runs now The Uno R4’s RA4M1 with a 12 x 8 LED matrix to draw on through Arduino_LED_Matrix.h. WiFi through WiFiS3.h on a simulated network: no radio, no ESP32-S3 in the model, no real internet. Open the board page ## 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 Open the editor