Simulator

RP2040 simulator: the Pico, the Pico W and the Nano RP2040 Connect, free online

Mokxi is a free Raspberry Pi Pico simulator that runs in your browser, with nothing to install and no account needed. Mokxi models every RP2040 board it ships, the Raspberry Pi Pico first, on our own Cortex-M0+ core, running the chip at 125 MHz on its real register map, so a build that runs here runs on the board on your desk.

  • 505parts on the bench
  • 45boards running now
  • 1.00xreal time, on every board
Pico: blinklive0.000 s 0.00x
Click to open it in the editor
Real firmware, running right now on our own core. Click it to open the circuit in the editor.
What is modeled

The numbers, not the marketing

Taken from the board's own contract document and put in plain words.

The coreCortex-M0+ (ARMv6-M), one core, at 125 MHz, with the datasheet cycle count of every instruction.
PeripheralsSIO GPIO on the real IO_BANK0, PADS_BANK0 and SIO offsets, a 64-bit microsecond timer with four alarms, UART0, eight PWM slices with two channels each, so analogWrite works on every GPIO pin, and the ADC on GP26 to GP28.
What is not there yetThe second core and PIO, and for an Arduino sketch DMA and the I2C and SPI blocks: Wire and SPI run in software on the pins. SIO.CPUID reads 0.
Go further

The full board page

Every peripheral area, every example and the wiring notes, in one place.

Raspberry Pi Pico simulatorBlink, a button and the serial monitor, running.
How it works

Three steps from a blank tab to a running circuit.

  1. Open the editor

    It runs in your browser tab. Nothing to install, and you need no account to start.

    Your first project
  2. Wire it and write the code

    Drag parts onto a breadboard, run each wire from pin to pin, and write the sketch beside it.

    Wiring
  3. Press Run

    Your sketch compiles in the tab and runs on a model of the chip, with the Serial Monitor beside it.

    Run and serial
Reviews

What makers say about Mokxi.

“The AI checker helps check and correct my circuits, and it has way more components than Tinkercad. As a student I really appreciate the tool.”

ChloeEngineering student

“I’d been looking for a real online electronic simulator that was intuitive and complete when I found Mokxi. I was able to quickly import a Fritzing file and my Arduino sketch and start testing. Mokxi has all of the makings for the best online Arduino simulator I have been able to find!”

JayModel builderFeatured in his DioramaOS post

“I’m using Mokxi to develop and simulate an STM32-based four-wheel-drive robot car before building the actual hardware. It allows me to experiment with DC motor control, PWM, RPM measurement using photointerrupters, and different acceleration, braking, and reversing strategies, helping me understand and refine the system before implementing it in real life.”

NusretRobot car builder, Hamburg

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FAQ

Questions, answered.

Which Pico boards can I simulate?

The original Raspberry Pi Pico runs above. The Pico W and the Arduino Nano RP2040 Connect run on the same RP2040 model, each as its own board with its own pinout.

Can I write MicroPython or CircuitPython?

Yes. Choose MicroPython (main.py) in the Pico’s Firmware panel and the official MicroPython v1.29.0 firmware runs your main.py, with machine.Pin, PWM, ADC, I2C and SPI. The MicroPython simulator page has the details. Choose CircuitPython (code.py) instead and the official CircuitPython 10.3.1 firmware runs your code.py, with the Adafruit libraries it imports.

Does it run Pico SDK binaries?

Two: the official MicroPython and CircuitPython firmware, both built on the Pico SDK, boot here through the RP2040’s boot ROM. There is no way to load an SDK program of your own; C++ here is Arduino-style, built in the tab on our own runtime.

Does it simulate PIO or the ADC?

The ADC, yes: analogRead on GP26 to GP28 reads the voltage on the net. PIO and the second core are not modeled, and touching them stops the program with a bus fault rather than reading a silent zero. Wokwi simulates PIO, if your project depends on it.

Can I use I2C and SPI parts?

Yes, through the Wire and SPI libraries, which drive the bus from the pins. Displays and sensors such as the SSD1306 OLED and the I2C LCD work on the Pico that way.

Will my firmware run on a real Pico?

Yes, as long as it does not reach for the second core, PIO or DMA. Download for your board builds a .uf2 for the real Pico, to drag onto it over USB.

Is it free?

Yes, with no card and no account needed to try it.

Simulators for one kind of circuit

A servo, a display, a motor driver or a rectifier, each already running.

Try your own firmware on the Pico

What you build here runs on the board on your desk, unchanged. Nothing to install and no account needed.