These are some of the common questions regarding CircuitPython and CircuitPython microcontrollers.

As CircuitPython development continues and there are new releases, Adafruit will stop supporting older releases. Visit to download the latest version of CircuitPython for your board. You must download the CircuitPython Library Bundle that matches your version of CircuitPython. Please update CircuitPython and then visit to download the latest Library Bundle.
I have to continue using CircuitPython 6.x or earlier. Where can I find compatible libraries?

We are no longer building or supporting the CircuitPython 6.x or earlier library bundles. We highly encourage you to update CircuitPython to the latest version and use the current version of the libraries. However, if for some reason you cannot update, here are the last available library bundles for older versions:

Is ESP8266 or ESP32 supported in CircuitPython? Why not?

We dropped ESP8266 support as of 4.x - For more information please read about it here!

As of CircuitPython 8.x we have started to support ESP32 and have added a WiFi workflow for wireless coding!

We also support ESP32-S2 & ESP32-S3, which has native USB.

How do I connect to the Internet with CircuitPython?

If you'd like to include WiFi in  your project, your best bet is to use a board that is running natively on ESP32 chipsets - those have WiFi built in!

If your development board has an SPI port and at least 4 additional pins, you can check out this guide on using AirLift with CircuitPython - extra wiring is required and some boards like the MacroPad or NeoTrellis do not have enough available pins to add the hardware support.

For further project examples, and guides about using AirLift with specific hardware, check out the Adafruit Learn System.

Is there asyncio support in CircuitPython?

There is support for asyncio starting with CircuitPython 7.1.0. Read about using it in the Cooperative Multitasking in CircuitPython Guide.

My RGB NeoPixel/DotStar LED is blinking funny colors - what does it mean?

The status LED can tell you what's going on with your CircuitPython board. Read more here for what the colors mean!

What is a MemoryError?

Memory allocation errors happen when you're trying to store too much on the board. The CircuitPython microcontroller boards have a limited amount of memory available. You can have about 250 lines of code on the M0 Express boards. If you try to import too many libraries, a combination of large libraries, or run a program with too many lines of code, your code will fail to run and you will receive a MemoryError in the serial console.

What do I do when I encounter a MemoryError?

Try resetting your board. Each time you reset the board, it reallocates the memory. While this is unlikely to resolve your issue, it's a simple step and is worth trying.

Make sure you are using .mpy versions of libraries. All of the CircuitPython libraries are available in the bundle in a .mpy format which takes up less memory than .py format. Be sure that you're using the latest library bundle for your version of CircuitPython.

If that does not resolve your issue, try shortening your code. Shorten comments, remove extraneous or unneeded code, or any other clean up you can do to shorten your code. If you're using a lot of functions, you could try moving those into a separate library, creating a .mpy of that library, and importing it into your code.

You can turn your entire file into a .mpy and import that into This means you will be unable to edit your code live on the board, but it can save you space.

Can the order of my import statements affect memory?

It can because the memory gets fragmented differently depending on allocation order and the size of objects. Loading .mpy files uses less memory so its recommended to do that for files you aren't editing.

How can I create my own .mpy files?

You can make your own .mpy versions of files with mpy-cross.

You can download mpy-cross for your operating system from here. Builds are available for Windows, macOS, x64 Linux, and Raspberry Pi Linux. Choose the latest mpy-cross whose version matches the version of CircuitPython you are using.

To make a .mpy file, run ./mpy-cross path/to/ to create a yourfile.mpy in the same directory as the original file.

How do I check how much memory I have free?

Run the following to see the number of bytes available for use:

import gc

Does CircuitPython support interrupts?

No. CircuitPython does not currently support interrupts - please use asyncio for multitasking / 'threaded' control of your code

Does Feather M0 support WINC1500?

No, WINC1500 will not fit into the M0 flash space.

Can AVRs such as ATmega328 or ATmega2560 run CircuitPython?


This guide was first published on Oct 12, 2021. It was last updated on 2022-02-14 16:45:58 -0500.

This page (Frequently Asked Questions) was last updated on Sep 26, 2022.

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