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Device Simulator Express, a Microsoft Garage project
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Device Simulator Express, a Microsoft Garage project

Make without limit! Device Simulator Express, a Microsoft Garage project, allows you to code in CircuitPython for your awesome Circuit Playground Express (CPX) projects! Test and debug your code on the device simulator and see the same result when you plug in your actual microcontroller. Curious about the output of the device, the serial monitor allows you to observe the device output.

CircuitPlayground Express


  • IntelliSense and syntax highlighting for CircuitPython code (only supports CPX Express library)
  • Template file generation
  • Integrated Python Debugging for the Simulator
  • Serial monitor (available on Windows and Mac only)
  • Output panel for the simulator
  • Deploy CircuitPython code to the physical device.
  • Simulation of the Adafruit Circuit Playground Express device, including:
    • Green LED
    • Red LED
    • Push Buttons A and B
    • Slider Switch
    • Speaker: Play .wav file
    • 10 NeoPixels
    • Light sensor
    • Motion sensors
    • Acceleration detection
    • Device shake detection
    • Temperature sensor
    • 7 Capacitive Touch sensors

The simulator supports most of the sensors on CPX except IR transmitter & Receiver, Sound Sensor (microphone), Speaker (Play Tone) and the “tap” on Motion Sensor. The code related to these sensors can still run on the actual CPX board and be deployed using Device Simulator Express.
As we only support CPX library now, other libraries (i.e. simpleio) can’t run on the simulator. But they will work on the actual device!


The following dependencies are required to install before launching Device Simulator Express.
You will be prompted to install the Python dependencies during the first use.

The following dependecies can be installed for you by the extension by clicking yes when you are prompted to (except pywin32 which is needed only on Windows platform). (2)

  • Playsound
    install by typing the following commands in a console: pip install playsound

  • Pywin 32
    install by typing the following commands in a console (only for Windows computers, you must run it manually): pip install pywin32

  • Python-Socketio
    install by typing the following commands in a console: pip install python-socketio

  • Requests
    install by typing the following commands in a console: pip install requests

  • Application Insights
    install by typing the following commands in a console: pip install applicationinsights

Useful Links

How to use

To use Device Simulator Express, install the extension from the marketplace and reload VS Code.

1. Start with the “New File” Command.

  1. Type in Device Simulator Express: New File” in the command palette(CTRL+SHIFT+Pto open the command palette).
    "New File" animation
  2. Name and save your file somewhere, and we’re good to go!(3)
  3. Start with some examples: you can find examples files and tutorials inside the comments, as well as in the notification pop up when you run the “Device Simulator Express: New File” Command.

How to find example code screenshot

2. Start from an existing python file.

  1. Open the folder or your .py file in Visual Studio Code.
  2. Run open Simulator from the command palette or icon in the editor toolbar.

3. Run your code on the simulator .

How to run the simulator animation

  • Run Run Simulator from the command palette or icon in the editor toolbar.
  • You can use the Play or Refresh button on the simulator webview.

4. Deploy your code to the physical device

Before deploying the python code to your CPX device, you need to format your device following these tutorials:

  1. Download the firmware with the .uf2 file (link:
  2. Download the lastest version of the cpx library (link:
    Note: Make sure you name your file or the device automatically runs the first file that is likely named.

"Deploy to Device" example

5. Use the Serial Monitor for your Adafruit CPX device(available Windows and Mac only)

  1. Plug in your CPX device (make sure it’s formatted properly already)
  2. Run the command Device Simulator Express: Open Serial Monitor
  3. Select your baud rate for the serial port
  4. The print() statements in your code will show in the output console

6. Use the sensors in the Device Simulator Express

Generating input for the sensors can be done by interacting directly with device on the webview or by using the toolbar.

  • Switch, push buttons and capacitive touch: click directly on the corresponding element on the device or use the keybindings.
  • Temperature sensor, Light sensor, acceleration: click on the corresponding button in the toolbar and change the value using the slider or the input box attached to it.
  • Shake detection: go to the motion sensor section in the toolbar and click on the shake button.

7. Debug your project on the simulator

  1. Add breakpoints in your code
  2. Press F5 to enter the debugging mode, and you can start debugging line by line!


Device Simulator Express provides several commands in the Command Palette (F1 or Ctrl + Shift + P/ Cmd + Shift + P for Mac OS) for working with *.py files:

  • Device Simulator Express: New File: Opens an unsaved .py file with template code, also open the simulator.
  • Device Simulator Express: Open Simulator: Opens the simulator in the webView
  • Device Simulator Express: Run on Simulator: Runs python code on the simulator
  • Device Simulator Express: Deploy to Device: Copies & Pastes the or file to CIRCUITPY drive if detected a CPX is plugged in
  • Device Simulator Express: Open Serial Monitor: Opens the serial monitor in the integrated output window.
  • Device Simulator Express: Close Serial Monitor: Stops the serial monitor and releases the serial port.
  • Device Simulator Express: Change Baud Rate: Changes the baud rate of the selected serial port. For Adafruit CPX, the default baud rate is 115200.
  • Device Simulator Express: Select Serial Port: Changes the current serial port.


In Device Simulator Express, you can use keyboard to interact with the device:

  • Push Button A & B: A B
  • Capacitive Touch Sensor A1 – A7: SHIFT + 1~7
  • Slider Switch: SHIFT + S
  • Refresh the simulator: SHIFT + R

Provide feedback

To report issues, provide feedback or requests, please use this link: Provide Feedback.
We would love to hear from you about your experience to keep improving our project.

Privacy and Telemetry Notice

Data Collection

The software may collect information about you and your use of the software and send it to Microsoft. Microsoft may use this information to provide services and improve our products and services. You may turn off the telemetry as described in the repository. There are also some features in the software that may enable you and Microsoft to collect data from users of your applications. If you use these features, you must comply with applicable law, including providing appropriate notices to users of your applications together with a copy of Microsoft's privacy statement. Our privacy statement is located at You can learn more about data collection and use in the help documentation and our privacy statement. Your use of the software operates as your consent to these practices.

Disable Telemetry

The Microsoft Device Simulator Express Extension for Visual Studio Code collects usage data and sends it to Microsoft to help improve our products and services. Read our privacy statement to learn more. This extension respects the telemetry.enableTelemetry setting which you can learn more about at

To disable telemetry, follow these steps:

  1. Open File (Open Code on macOS)
  2. Select Preferences
  3. Select Settings
  4. Search for telemetry
  5. Uncheck the Telemetry: Enable Telemetry setting

Third Party Notice

A ThirdPartyNotices.txt file is provided in the extension's source code listing the appropriate third-party notices.

Troubleshooting Tips

  • The first time you install the extension, you'll need to execute the run command at least once in order to access auto-completion.
  • While running a code file, if you get an error saying it can't find the file, make sure you've clicked on a valid Python code file before running it.
  • To open the output panel again after closing it go to VS Code menu: View->Output.
  • If you have pylint enabled, it might underline the import of the adafruit_circuitplayground library, but it will work correctly.
  • If you try to deploy to the device while it's plugged in but you still get an error saying it cannot find the board, make sure your Circuit Playground Express is formatted correctly and that its name matches CIRCUITPY.
  • If you can't get the Simulator communication working while debugging, try to open your Settings and check the port used under 'Device Simulator Express: Debugger Server Port'. You can either change it (usually ports above 5000 should work) or try to free it, then start debugging again.
  • When you are using the serial monitor, if you get some unusual error messages, unplug the device and reload the VS Code windows.


Device Simulator Express, a Microsoft Garage project

Copyright (c) Microsoft Corporation. All rights reserved.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.



(1) Note: the easiest way to do it is to select the "Add to PATH" option directly when you install Python. Otherwise you can search how to insert it manually, but make sure that when you type python in a terminal, the command is recognized and have the correct version. (2) You can chose to see to see the prompt or not by changing the extension configirations. (3) To be able to run the file from your physical device, it should either be named or

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