Introducing Adafruit ItsyBitsy M4
Created by lady ada
https://learn.adafruit.com/introducing-adafruit-itsybitsy-m4
Last updated on 2022-01-01 02:32:13 PM EST
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Table of Contents
Overview
Update the UF2 Bootloader
• Updating Your Bootloader
Pinouts
• Power Pins
• Logic pins
• QSPI Flash and DotStar
• Other Pins
Arduino IDE Setup
Using with Arduino IDE
• Install SAMD Support
• Install Adafruit SAMD
• Install Drivers (Windows 7 & 8 Only)
• Blink
• Successful Upload
• Compilation Issues
• Manually bootloading
• Ubuntu& Linux Issue Fix
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Adapting Sketches to M0 & M4
• Analog References
• Pin Outputs & Pullups
• Serial vs SerialUSB
• AnalogWrite / PWM on Feather/Metro M0
• analogWrite() PWM range
• analogWrite() DAC on A0
• Missing header files
• Bootloader Launching
• Aligned Memory Access
• Floating Point Conversion
• How Much RAM Available?
• Storing data in FLASH
• Pretty-Printing out registers
• M4 Performance Options
• CPU Speed (overclocking)
• Optimize
• Cache
• Max SPI and Max QSPI
• Enabling the Buck Converter on some M4 Boards
What is CircuitPython?
• CircuitPython is based on Python
• Why would I use CircuitPython?
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CircuitPython on ItsyBitsy
• Set up CircuitPython Quick Start!
• Further Information
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Installing the Mu Editor
• Download and Install Mu
• Starting Up Mu
• Using Mu
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Creating and Editing Code
• Creating Code
• Editing Code
• Back to Editing Code...
• Naming Your Program File
Connecting to the Serial Console
• Are you using Mu?
• Serial Console Issues or Delays on Linux
• Setting Permissions on Linux
• Using Something Else?
Interacting with the Serial Console
The REPL
• Entering the REPL
• Interacting with the REPL
• Returning to the Serial Console
CircuitPython Libraries
• The Adafruit CircuitPython Library Bundle
• Downloading the Adafruit CircuitPython Library Bundle
• The CircuitPython Community Library Bundle
• Downloading the CircuitPython Community Library Bundle
• Understanding the Bundle
• Example Files
• Copying Libraries to Your Board
• Understanding Which Libraries to Install
• Example: ImportError Due to Missing Library
• Library Install on Non-Express Boards
• Updating CircuitPython Libraries and Examples
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Frequently Asked Questions
Welcome to the Community!
• Adafruit Discord
• CircuitPython.org
• Adafruit GitHub
• Adafruit Forums
• Read the Docs
Advanced Serial Console on Windows
• Windows 7 and 8.1
• What's the COM?
• Install Putty
Advanced Serial Console on Mac
• What's the Port?
• Connect with screen
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"Uninstalling" CircuitPython
• Backup Your Code
• Moving Circuit Playground Express to MakeCode
• Moving to Arduino
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Troubleshooting
• Always Run the Latest Version of CircuitPython and Libraries
• I have to continue using CircuitPython 5.x or earlier. Where can I find compatible libraries?
• Bootloader (boardnameBOOT) Drive Not Present
• Windows Explorer Locks Up When Accessing boardnameBOOT Drive
• Copying UF2 to boardnameBOOT Drive Hangs at 0% Copied
• CIRCUITPY Drive Does Not Appear
• Device Errors or Problems on Windows
• Serial Console in Mu Not Displaying Anything
• code.py Restarts Constantly
• CircuitPython RGB Status Light
• CircuitPython 7.0.0 and Later
• CircuitPython 6.3.0 and earlier
• Serial console showing ValueError: Incompatible .mpy file
• CIRCUITPY Drive Issues
• Safe Mode
• To erase CIRCUITPY: storage.erase_filesystem()
• Erase CIRCUITPY Without Access to the REPL
• For the specific boards listed below:
• For SAMD21 non-Express boards that have a UF2 bootloader:
• For SAMD21 non-Express boards that do not have a UF2 bootloader:
• Running Out of File Space on SAMD21 Non-Express Boards
• Delete something!
• Use tabs
• On MacOS?
• Prevent & Remove MacOS Hidden Files
• Copy Files on MacOS Without Creating Hidden Files
• Other MacOS Space-Saving Tips
• Device Locked Up or Boot Looping
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CircuitPython Essentials
CircuitPython Pins and Modules
• CircuitPython Pins
• import board
• I2C, SPI, and UART
• What Are All the Available Names?
• Microcontroller Pin Names
• CircuitPython Built-In Modules
CircuitPython Built-Ins
• Thing That Are Built In and Work
• Flow Control
• Math
• Tuples, Lists, Arrays, and Dictionaries
• Classes, Objects and Functions
• Lambdas
• Random Numbers
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CircuitPython Digital In & Out
• Find the pins!
• Read the Docs
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CircuitPython Analog In
• Creating the analog input
• get_voltage Helper
• Main Loop
• Changing It Up
• Wire it up
• Reading Analog Pin Values
CircuitPython Analog Out
• Creating an analog output
• Setting the analog output
• Main Loop
• Find the pin
CircuitPython PWM
• PWM with Fixed Frequency
• Create a PWM Output
• Main Loop
• PWM Output with Variable Frequency
• Wire it up
• Where's My PWM?
CircuitPython Servo
• Servo Wiring
• Standard Servo Code
• Continuous Servo Code
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CircuitPython Internal RGB LED
• Create the LED
• Brightness
• Main Loop
• Making Rainbows (Because Who Doesn't Love 'Em!)
• Circuit Playground Express Rainbow
CircuitPython NeoPixel
• Wiring It Up
• The Code
• Create the LED
• NeoPixel Helpers
• Main Loop
• NeoPixel RGBW
• Read the Docs
CircuitPython DotStar
• Wire It Up
• The Code
• Create the LED
• DotStar Helpers
• Main Loop
• Is it SPI?
• Read the Docs
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CircuitPython UART Serial
• The Code
• Wire It Up
• Where's my UART?
• Trinket M0: Create UART before I2C
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CircuitPython I2C
• Wire It Up
• Find Your Sensor
• I2C Sensor Data
• Where's my I2C?
CircuitPython HID Keyboard and Mouse
• CircuitPython Keyboard Emulator
• Create the Objects and Variables
• The Main Loop
• Non-US Keyboard Layouts
• CircuitPython Mouse Emulator
• Create the Objects and Variables
• CircuitPython HID Mouse Helpers
• Main Loop
CircuitPython CPU Temp
• Microcontroller Location
• Reading the Microcontroller Temperature
CircuitPython Storage
• Logging the Temperature
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CircuitPython Expectations
• Always Run the Latest Version of CircuitPython and Libraries
• I have to continue using CircuitPython 3.x or 2.x, where can I find compatible libraries?
• Switching Between CircuitPython and Arduino
• The Difference Between Express And Non-Express Boards
• Non-Express Boards: Gemma, Trinket, and QT Py
• Differences Between CircuitPython and MicroPython
• Differences Between CircuitPython and Python
UF2 Bootloader Details
• Entering Bootloader Mode
• Using the Mass Storage Bootloader
• Using the BOSSA Bootloader
• Running bossac on the command line
• Updating the bootloader
• Getting Rid of Windows Pop-ups
• Making your own UF2
• Installing the bootloader on a fresh/bricked board
Downloads
• Files
• Schematic & Fabrication Print
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Overview
What's smaller than a Feather but larger than a Trinket? It's an Adafruit ItsyBitsy M4
Express featuring the Microchip ATSAMD51! Small, powerful, with a ultra fast
ATSAMD51 Cortex M4 processor running at 120 MHz - this microcontroller board is
perfect when you want something very compact, with a ton of horsepower and a
bunch of pins. This Itsy is like a bullet train, with it's 120MHz Cortex M4 with floating
point support and 512KB Flash and 192KB RAM. Your code will zig and zag and zoom,
and with a bunch of extra peripherals for support, this will for sure be your favorite
new chipset.
ItsyBitsy M4 Express is only is only 1.4" long by 0.7" wide, but has 6 power pins, 23
digital GPIO pins (7 of which can be analog in, 2 x 1 MSPS analog out DACs, and 18 x
PWM out). It's the same basic chip as the Adafruit Metro M4(https://adafru.it/A5S) but
really really small. So it's great once you've finished up a prototype on a Metro M4 or
(the upcoming) Feather M4, and want to make the project much smaller. It even
comes with 2MB of SPI Flash built in, for data logging, file storage, or CircuitPython
code.
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The most exciting part of the ItsyBitsy M4 is that while you can use it with the Arduino
IDE, we are shipping it with CircuitPython on board. When you plug it in, it will show
up as a very small disk drive with main.py on it. Edit main.py with your favorite text
editor to build your project using Python, the most popular programming language.
No installs, IDE or compiler needed, so you can use it on any computer, even
ChromeBooks or computers you can't install software on. When you're done, unplug
the Itsy' and your code will go with you.
You can also use MakeCode(https://adafru.it/C9N)'s block-based GUI coding
environment on this board.
Here are some of the updates you can look forward to when using ItsyBitsy M4:
Same size, form-factor as the ItsyBitsy 32u4(https://adafru.it/BjC) and ItsyBitsy
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M0(https://adafru.it/Bl9), and nearly-identical pinout as both
ATSAMD51G19A 32-bit Cortex M4 core running at 120 MHz
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Hardware DSP and floating point support
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512 KB flash, 192 KB RAM
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2 MB SPI FLASH chip for storing files and CircuitPython code storage.
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32-bit, 3.3V logic and power
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Tons of GPIO! 23 x GPIO pins with following capabilities:
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Dual 1 MSPS 12 bit true analog DAC (A0 and A1) - can be used to play 12-bit
◦
stereo audio clips
Dual 1 MSPS 12 bit ADC (7 analog pins some on ADC1 and some on ADC2)
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6 x hardware SERCOM - Native hardware SPI, I2C and Serial all available
◦
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18 x PWM outputs- for servos, LEDs, etc
◦
No I2S. We have no idea why but I2S is only supported on the 64 pin
◦
version of this chip (ATSAMD51J19A) and we could only fit the 48 pin
version (the ATSAMD51G19A) on this board. But there's a stereo DAC you
could use?
8-bit Parallel capture controller (for camera/video in)
◦
1 x Special Vhigh output pin gives you the higher voltage from VBAT or
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VUSB, for driving NeoPixels, servos, and other 5V-logic devices. Digital 5
level-shifted output for high-voltage logic level output.
Can driveNeoPixels or DotStars on any pins, with enough memory to drive
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60,000+ pixels.DMA-NeoPixel support on the VHigh pin(https://adafru.it/
xYD)so you can drive pixels without having to spend any processor time on
it.
Built in crypto engines with AES (256 bit), true RNG, Pubkey controller
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Native USB supported by every OS- can be used in Arduino or CircuitPython as
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USB serial console, Keyboard/Mouse HID, even a little disk drive for storing
Python scripts.
Can be used withArduino IDEorCircuitPython
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Built in red pin #13 LED
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Built in RGB DotStar LED
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Reset button and pin
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Power with either USB or external output (such as a battery) - it'll automatically
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switch over
Comes pre-loaded with theUF2 bootloader(https://adafru.it/wbC), which looks
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like a USB storage key. Simply drag firmware on to program, no special tools or
drivers needed! It can be used to load up CircuitPython or Arduino IDE (it is
bossa v1.8 compatible)
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Each order comes with one assembled and tested ItsyBitsy M4, with headers that can
be soldered in for use with a breadboard. ItsyBitsy M4 comes with CircuitPython
programmed in, but you can replace the code with Arduino if you like.
So what are you waiting for? Pick up a ItsyBitsy M4 today and be amazed at how easy
and fast it is to get started with CircuitPython!
Update the UF2 Bootloader
Update the Bootloader on your SAMD51 M4 board to prevent a somewhat rare
problem of parts of internal flash being overwritten on power-up.
Your SAMD51 M4 board bootloader may need to be updated to fix an intermittent bug
that can erase parts of internal flash.
Updating Your Bootloader
To see if you need to update your bootloader, get the UF2 boot drive to appear as a
mounted drive on your computer, in a file browser window. If you're running
MakeCode, click the reset button once. If you're running CircuitPython or an Arduino
program, double-click the reset button.
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When you see the ...BOOT drive (FEATHERBOOT, METROM4BOOT, ITSYM4BOOT, PO
RTALBOOT, etc.) , click the drive in the file browser window and then double-click the
INFO_UF2.TXT file to see what's inside.
The example screenshots below are for a PyGamer. What you see for your board will
be largely the same except for the board name and the BOOT drive name.
The bootloader version is listed in INFO_UF2.TXT. In this example, the version is v3.6
.0.
If the bootloader version you see is older than v3.9.0, you need to update. For
instance, the bootloader above needs to be upgraded.
Download the latest version of the bootloader updater from the circuitpython.org
Downloads page for your board.
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Latest board downloads
https://adafru.it/Em8
The bootloader updater will be named update-bootloader-
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name_of_your_board-v3.9.0.uf2or some later version. Drag that file from your D
ownloads folder onto the BOOT drive:
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After you drag the updater onto the boot drive, the red LED on the board will flicker
and then blink slowly about five times. A few seconds later, the BOOT will appear in
the Finder. After that, you can click on the BOOT drive and double-click INFO_UF2.T
XT again to confirm you've updated the bootloader.
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Pinouts
Power Pins
The ItsyBitsy M4 Express has BAT G USB
on the top left, right next to the micro
USB port
These pins are:
BAT - battery input for an
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alternative power source to USB,
the voltage can only be from 3.5V
to 6VDC
GND - Power/data ground
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USB - This is the same pin as the
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MicroUSB connector's 5V USB
power pin. This should be used as
an output to get 5V power from the
USB port. Say if you need to power
a bunch of NeoPixels or servos.
You can always put any voltage you like into BAT and the circuitry will switch between
BAT and USB dynamically for you. That means you can have a Batter backup that only
gets enabled when USB is disconnected.
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If you want to add rechargeable power, a LiPoly backpack can be soldered into these
three pins that will let you have a battery that is automatically recharged whenever
USB is plugged in, then switches to LiPoly when on the go:
Adafruit LiIon/LiPoly Backpack Add-On for
Pro Trinket/ItsyBitsy
If you have an ItsyBitsy or Pro Trinket you
probably know it's the perfect little size
for a portable project. This LiPoly
backpack makes it really easy to do!
Instead of wiring 2...
https://www.adafruit.com/product/2124
In addition to the three standard power pins, the ItsyBitsy M4 Express has a few more
pins available for power sourcing:
3V - this is the regulated output from the onboard regulator. You can draw
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500mA whether powered by USB or battery.
Vhi - this is a special pin! It is a dual-Schottkey-diode connected output from BA
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T and USB. This means this will always have the higher-of-the-two voltages, but
will always have power output. The voltage will about 5VDC when powered by
USB, but can range from 3.5-6VDC when powered from battery. It's not
regulated, but it is high-current, great for driving servos and NeoPixels.
EN - connected to the regulator enable, it will let you shut off power - when
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running on battery only. But at least you don't have to cut a trace or wire to your
battery. This pin does not affect power when using USB
Logic pins
This is the general purpose I/O pin set for the microcontroller. All logic is 3.3V. You
can usually use 3V logic as an input to 5V, but the 3V Itsy pins should not be
connected to 5V!
Nearly all pins can do PWM output
All pins can be interrupt inputs
Please note this chip has hardware support for Serial, I2C and SPI but does not
support I2S. We have no idea why but Atmel disabled I2S on the 48 QFN version of
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this chip. If you need I2S please pick up a Metro or Feather M4 as those use the I2Scapable 64-QFN ¯\_(ツ)_/¯
Along the right edge
#0 / RX - GPIO #0, also receive (input) pin for Serial1. PWM output
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#1 / TX - GPIO #1, also transmit (output) pin for Serial1. PWM output
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SDA and SCL - these are the I2C hardware interface pins. There's no pull up on
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this pin by default so when using with I2C, you may need a 2.2K-10K pullup on
each to 3.3V. PWM output
#5 - GPIO #5. This is a special OUTPUT-only pin that can PWM. It is level-shifted
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up to Vhi voltage, so its perfect for driving NeoPixels that want a ~5V logic level
input. You can use this with our NeoPixel DMA control library to automatically
write NeoPixel data without needing any processor time(https://adafru.it/BkV).
#7 - GPIO #7 can PWM
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#9 - GPIO #9 can PWM
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#10 - GPIO #10 can PWM
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#11 - GPIO #11 can PWM
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#12 - GPIO #12 can PWM
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#13 - GPIO #13 can PWM, is connected to the red LED next to the Reset button
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Along the left edge
A0 - This pin is analog input A0 but is also an analog output due to having a
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DAC (digital-to-analog converter). This is the first DAC, and is 'independent' of
A1. You can set the raw voltage to anything from 0 to 3.3V, unlike PWM outputs
this is a true analog output
A1 - This pin is analog input A1 but is also an analog output due to having a DAC
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(digital-to-analog converter). This is the second DAC, and is 'independent' of A0.
You can set the raw voltage to anything from 0 to 3.3V, unlike PWM outputs this
is a true analog output
A2 thru A5 - These are each analog input as well as digital I/O pins.A4 andA5
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havePWM output. (A4 and A5 cannot be used for PWM in CircuitPython.)
SCK/MOSI/MISO - These are the hardware SPI pins, you can use them as
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everyday GPIO pins but recommend keeping them free as they are best used
for hardware SPI connections for high speed.MOSI andSCK havePWM output.
(MOSI cannot be used for PWM in CircuitPython.)
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Along the short edge:
#2 - GPIO #2, also analog input A6and hasPWM output.
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#3 - GPIO #3.
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#4 - GPIO #4. Can also do PWM output
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SWCLK & SWDIO - These are the debug-interface pins, used if you want to
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reprogram the chip directly or attach a debugger.
These pins are available in CircuitPython under the board module. Names that start
with # are prefixed with D and other names are as is. So #0 / RX above is available as
board.D0 and board.RX for example.
Parallel Capture Peripheral
There's a 'camera' input peripheral you can use with some camera chips to capture
video with 8-bit data width. We thought this was neat so we made sure all those pins
were available. Here are the PCC pins (left) and the Itsy M4 pins it's mapped to. Unlike
other peripherals, you cannot mux these signals to other pins!
DEN1: SDA
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DEN2: SCL
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CLK: D4
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D0: RX
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D1: TX
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D2: D7
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D3: D9
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D4: D10
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D5: D11
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D6: D13
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D7: D12
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QSPI Flash and DotStar
As part of the 'Express' series of boards,
this ItsyBitsy is designed for use with
CircuitPython. To make that easy, we
have added two extra parts: a mini
DotStar (RGB LED) and a 2 MB QSPI
(Quad SPI) Flash chip
The DotStar is connected to pin #6 (clock) and #8 (data) in Arduino, so just use our
DotStar library(https://adafru.it/zbD) and set it up as a single-LED strand on pins 6 &
8. The DotStar is powered by the 3.3V power supply but that hasn't shown to make a
big difference in brightness or color. The DotStar is also used by the bootloader to let
you know if the device has enumerated correctly (green) or USB failure (red). In
CircuitPython, the LED is used to indicate the run time status.
The QSPI Flash is connected to 6 pins that are not brought out on the GPIO pads.
This way you don't have to worry about the SPI flash colliding with other devices on
the main SPI connection.
QSPI is neat because it allows you to have 4 data in/out lines instead of just SPI's
single line in and single line out. This means that QSPI is at least 4 times faster. But in
reality is at least 10x faster because you can clock the QSPI peripheral much faster
than a plain SPI peripheral
However, the QSPI port is not also on an SERCOM. So, you have to either use the
QSPI peripheral or bit-bang SPI if you want to talk to the chip. We have an Arduino
library here which provides QSPI interfacing for Arduino(https://adafru.it/BeX). In
CircuitPython, the QSPI flash is used natively by the interpreter and is read-only to
user code, instead the Flash just shows up as the writable disk drive!
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Other Pins
RST - this is the Reset pin, tie to
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ground to manually reset the
ATSAMD51, as well as launch the
bootloader manually
ARef - the analog reference pin.
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Normally the reference voltage is
the same as the chip logic voltage
(3.3V) but if you need an alternative
analog reference, connect it to this
pin and select the external AREF in
your firmware. Can't go higher than
3.3V!
Arduino IDE Setup
The first thing you will need to do is to download the latest release of the Arduino
IDE. You will need tobe using version 1.8 or higher for this guide
Arduino IDE Download
https://adafru.it/f1P
After you have downloaded and installed the latest version of Arduino IDE, you will
need to start the IDEand navigate tothe Preferences menu. You can access it from
the File menu in Windows or Linux, or the Arduino menu on OS X.
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A dialog will pop up just like the one shown below.
We will be adding a URL to the new Additional Boards Manager URLs option. The list
of URLs is comma separated, and you will only have to add eachURL once.New
Adafruit boards and updates to existing boardswill automatically be picked upby the
Board Manager each timeit is opened. The URLs point to index files that the Board
Manager uses to build the list of available & installed boards.
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To find the most up to date list of URLs you canadd, you can visit the list of third party
board URLs on the Arduino IDE wiki(https://adafru.it/f7U). We will only need to add
one URL to the IDE in this example, but you can add multiple URLS by separating
them with commas. Copy and paste the link below into theAdditional Boards
Manager URLs option in the Arduino IDE preferences.
https://adafruit.github.io/arduino-board-index/
package_adafruit_index.json
Here's a short description of each of the Adafruit supplied packages that will be
available in the Board Manager when you add the URL:
Adafruit AVR Boards - Includes support for Flora, Gemma, Feather 32u4,
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ItsyBitsy 32u4, Trinket, & Trinket Pro.
Adafruit SAMD Boards - Includes support for Feather M0 and M4, Metro M0 and
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M4, ItsyBitsy M0 and M4, Circuit Playground Express, Gemma M0 and Trinket
M0
Arduino Leonardo & Micro MIDI-USB - This adds MIDI over USB support for the
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Flora, Feather 32u4, Micro and Leonardo using the arcore project(https://
adafru.it/eSI).
If you have multiple boards you want to support, say ESP8266 and Adafruit, have
both URLs in the text box separated by a comma (,)
Once done click OK to save the new preference settings. Next we will look at
installing boards with the Board Manager.
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Now continue to the next step to actually install the board support package!
Using with Arduino IDE
The Feather/Metro/Gemma/QTPy/Trinket M0 and M4 use an ATSAMD21 or ATSAMD51
chip, and you can pretty easily get it working with the Arduino IDE. Most libraries
(including the popular ones like NeoPixels and display) will work with the M0 and M4,
especially devices & sensors that use I2C or SPI.
Now that you have added the appropriate URLs to the Arduino IDE preferences in the
previous page, you can open the Boards Manager by navigating to the Tools->Board
menu.
Once the Board Manager opens, click on the category drop down menu on the top
left hand side of the window and select All. You will then be able to select and install
the boards suppliedby the URLs added to the preferences.
Remember you need SETUP the Arduino IDE to support our board packages see the previous page on how to add adafruit's URL to the preferences
Install SAMD Support
First up, install the latest Arduino SAMD Boards (version 1.6.11or later)
You can type Arduino SAMD in the top search bar, then when you see the entry, click I
nstall
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Install Adafruit SAMD
Next you can install the Adafruit SAMD package to add the board file definitions
Make sure you have Type All selected to the left of the Filter your search... box
You can type Adafruit SAMD in the top search bar, then when you see the entry, click I
nstall
Even though in theory you don't need to - I recommend rebooting the IDE
Quit and reopenthe Arduino IDE to ensure that all of the boards are properly
installed. You should now be able to select and upload to the new boards listed in the
Tools->Board menu.
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Select the matching board, the current options are:
Feather M0 (for use with any Feather M0 other than the Express)
•
Feather M0 Express
•
Metro M0 Express
•
Circuit Playground Express
•
Gemma M0
•
Trinket M0
•
QT Py M0
•
ItsyBitsy M0
•
Hallowing M0
•
Crickit M0 (this is for direct programming of the Crickit, which is probably not
•
what you want! For advanced hacking only)
Metro M4 Express
•
Grand Central M4 Express
•
ItsyBitsy M4 Express
•
Feather M4 Express
•
Trellis M4 Express
•
PyPortal M4
•
PyPortal M4 Titano
•
PyBadge M4 Express
•
Metro M4 Airlift Lite
•
PyGamer M4 Express
•
MONSTER M4SK
•
Hallowing M4
•
MatrixPortal M4
•
BLM Badge
•
Install Drivers (Windows 7 & 8 Only)
When you plug in the board, you'll need to possibly install a driver
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Click below to download our Driver Installer
Download Latest Adafruit Drivers
package
https://adafru.it/mb8
Download and run the installer
Run the installer! Since we bundle the SiLabs and FTDI drivers as well, you'll need to
click through the license
Select which drivers you want to install, the defaults will set you up with just about
every Adafruit board!
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Click Install to do the installin'
Blink
Now you can upload your first blink sketch!
Plug in the M0 or M4 board, and wait for it to be recognized by the OS (just takes a
few seconds). It will create a serial/COM port, you can now select it from the dropdown, it'll even be 'indicated' as Trinket/Gemma/Metro/Feather/ItsyBitsy/Trellis!
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Please note, the QT Py and Trellis M4 Express are two of our very few boards that
does not have an onboard pin 13 LED so you can follow this section to practice
uploading but you wont see an LED blink!
Now load up the Blink example
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
And click upload! That's it, you will be able to see the LED blink rate change as you
adapt the delay() calls.
If you are having issues, make sure you selected the matching Board in the menu
that matches the hardware you have in your hand.
Successful Upload
If you have a successful upload, you'll get a bunch of red text that tells you that the
device was found and it was programmed, verified & reset
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After uploading, you may see a message saying "Disk NotEjectedProperly" about the
...BOOT drive. You can ignore that message: it's an artifact of how the bootloader and
uploading work.
Compilation Issues
If you get an alert that looks like
Cannot run program "{runtime.tools.arm-none-eabi-gcc.path}\bin\arm-non-eabi-g++"
Make sure you have installed the Arduino SAMD boards package, you need both Ard
uino & Adafruit SAMD board packages
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Manually bootloading
If you ever get in a 'weird' spot with the bootloader, or you have uploaded code that
crashes and doesn't auto-reboot into the bootloader, click the RST button twice (like a
double-click)to get back into the bootloader.
The red LED will pulse and/or RGB LED will be green, so you know that its in
bootloader mode.
Once it is in bootloader mode, you can select the newly created COM/Serial port and
re-try uploading.
You may need to go back and reselect the 'normal' USB serial port next time you want
to use the normal upload.
Ubuntu& Linux Issue Fix
Follow the steps for installing Adafruit's udev rules on this page.(https://adafru.it/iOE)
Adapting Sketches to M0 & M4
The ATSAMD21 and 51 are very nice little chips, but fairly new as Arduino-compatible
cores go. Most sketches & libraries will work but here’s a collection of things we
noticed.
The notes below cover a range of Adafruit M0 and M4 boards, but not every rule will
apply to every board (e.g. Trinket and Gemma M0 do not have ARef, so you can skip
the Analog References note!).
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Analog References
If you'd like to use the ARef pin for a non-3.3V analog reference, the code to use is
analogReference(AR_EXTERNAL) (it's AR_EXTERNAL not EXTERNAL)
Pin Outputs & Pullups
The old-style way of turning on a pin as an input with a pullup is to use
pinMode(pin, INPUT)
digitalWrite(pin, HIGH)
This is because the pullup-selection register on 8-bit AVR chips is the same as the
output-selection register.
For M0 & M4 boards, you can't do this anymore! Instead, use:
pinMode(pin, INPUT_PULLUP)
Code written this way still has the benefit of being backwards compatible with AVR.
You don’t need separate versions for the different board types.
Serial vs SerialUSB
99.9% of your existing Arduino sketches use Serial.print to debug and give output. For
the Official Arduino SAMD/M0 core, this goes to the Serial5 port, which isn't exposed
on the Feather. The USB port for the Official Arduino M0 core is called SerialUSB
instead.
In the Adafruit M0/M4 Core, we fixed it so that Serial goes to USB so it will
automatically work just fine.
However, on the off chance you are using the official Arduino SAMD core and not the
Adafruit version (which really, we recommend you use our version because it’s been
tuned to our boards), and you want your Serial prints and reads to use the USB port,
use SerialUSB instead of Serial in your sketch.
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If you have existing sketches and code and you want them to work with the M0
without a huge find-replace, put
#if defined(ARDUINO_SAMD_ZERO) && defined(SERIAL_PORT_USBVIRTUAL)
// Required for Serial on Zero based boards
#define Serial SERIAL_PORT_USBVIRTUAL
#endif
right above the first function definition in your code. For example:
AnalogWrite / PWM on Feather/Metro M0
After looking through the SAMD21 datasheet, we've found that some of the options
listed in the multiplexer table don't exist on the specific chip used in the Feather M0.
For all SAMD21 chips, there are two peripherals that can generate PWM signals: The
Timer/Counter (TC) and Timer/Counter for Control Applications (TCC). Each SAMD21
has multiple copies of each, called 'instances'.
Each TC instance has one count register, one control register, and two output
channels. Either channel can be enabled and disabled, and either channel can be
inverted. The pins connected to a TC instance can output identical versions of the
same PWM waveform, or complementary waveforms.
Each TCC instance has a single count register, but multiple compare registers and
output channels. There are options for different kinds of waveform, interleaved
switching, programmable dead time, and so on.
The biggest members of the SAMD21 family have five TC instances with two
'waveform output' (WO) channels, and three TCC instances with eight WO channels:
TC[0-4],WO[0-1]
•
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TCC[0-2],WO[0-7]
•
And those are the onesshown in the datasheet's multiplexer tables.
The SAMD21G used in the Feather M0 only has three TC instances with two output
channels, and three TCC instances with eightoutput channels:
TC[3-5],WO[0-1]
•
TCC[0-2],WO[0-7]
•
Tracing the signals to the pins broken out on the Feather M0, the following pins can't
do PWM at all:
Analog pin A5
•
The following pins can be configured for PWM without any signal conflicts as long as
the SPI, I2C, and UART pins keep their protocol functions:
Digital pins 5, 6, 9, 10, 11, 12, and 13
•
Analog pins A3 and A4
•
If only the SPI pins keep their protocol functions, you can also do PWM on the
following pins:
TX and SDA (Digital pins 1 and 20)
•
analogWrite() PWM range
On AVR, if you set a pin's PWM with analogWrite(pin, 255) it will turn the pin fully
HIGH. On the ARM cortex, it will set it to be 255/256 so there will be very slim but
still-existing pulses-to-0V. If you need the pin to be fully on, add test code that checks
if you are trying to analogWrite(pin, 255) and, instead, does a digitalWrite(p
in, HIGH)
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analogWrite() DAC on A0
If you are trying to use analogWrite() to control the DAC output on A0, make sure
you do not have a line that sets the pin to output. Remove: pinMode(A0, OUTPUT) .
Missing header files
There might be code that uses libraries that are not supported by the M0 core. For
example if you have a line with
#include <util/delay.h>
you'll get an error that says
fatal error: util/delay.h: No such file or directory
#include <util/delay.h>
^
compilation terminated.
Error compiling.
In which case you can simply locate where the line is (the error will give you the file
name and line number) and 'wrap it' with #ifdef's so it looks like:
#if !defined(ARDUINO_ARCH_SAM) && !defined(ARDUINO_ARCH_SAMD) && !
defined(ESP8266) && !defined(ARDUINO_ARCH_STM32F2)
#include <util/delay.h>
#endif
The above will also make sure that header file isn't included for other architectures
If the #include is in the arduino sketch itself, you can try just removing the line.
Bootloader Launching
For most other AVRs, clicking reset while plugged into USB will launch the bootloader
manually, the bootloader will time out after a few seconds. For the M0/M4, you'll need
to double click the button. You will see a pulsing red LED to let you know you're in
bootloader mode. Once in that mode, it wont time out! Click reset again if you want to
go back to launching code.
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Aligned Memory Access
This is a little less likely to happen to you but it happened to me! If you're used to 8bit platforms, you can do this nice thing where you can typecast variables around. e.g.
uint8_t mybuffer[4];
float f = (float)mybuffer;
You can't be guaranteed that this will work on a 32-bit platform because mybuffer
might not be aligned to a 2 or 4-byte boundary. The ARM Cortex-M0 can only directly
access data on 16-bit boundaries (every 2 or 4 bytes). Trying to access an oddboundary byte (on a 1 or 3 byte location) will cause a Hard Fault and stop the MCU.
Thankfully, there's an easy work around ... just use memcpy!
uint8_t mybuffer[4];
float f;
memcpy(&f, mybuffer, 4)
Floating Point Conversion
Like the AVRArduinos, the M0 library does not have full support for converting
floating point numbers to ASCII strings. Functions like sprintf will not convert floating
point. Fortunately, the standard AVR-LIBC library includes the dtostrf function which
can handle the conversion for you.
Unfortunately, the M0 run-time library does not have dtostrf. You may see some
references to using #include <avr/dtostrf.h> to get dtostrf in your code. And while it
will compile, it does not work.
Instead, check out this thread to find a working dtostrffunction you can include in
your code:
http://forum.arduino.cc/index.php?topic=368720.0(https://adafru.it/lFS)
How Much RAM Available?
The ATSAMD21G18 has 32K of RAM, but you still might need to track it for some
reason. You can do so with this handy function:
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extern "C" char *sbrk(int i);
int FreeRam () {
char stack_dummy = 0;
return &stack_dummy - sbrk(0);
}
Thx to http://forum.arduino.cc/index.php?topic=365830.msg2542879#msg2542879(h
ttps://adafru.it/m6D) for the tip!
Storing data in FLASH
If you're used to AVR, you've probably used PROGMEM to let the compiler know
you'd like to put a variable or string in flash memory to save on RAM. On the ARM, its
a little easier, simply add const before the variable name:
const char str[] = "My very long string";
That string is now in FLASH. You can manipulate the string just like RAM data, the
compiler will automatically read from FLASH so you dont need special progmemknowledgeable functions.
You can verify where data is stored by printing out the address:
Serial.print("Address of str $"); Serial.println((int)&str, HEX);
If the address is $2000000 or larger, its in SRAM. If the address is between $0000
and $3FFFF Then it is in FLASH
Pretty-Printing out registers
There's a lot of registers on the SAMD21, and you often are going through ASF or
another framework to get to them. So having a way to see exactly what's going on is
handy. This library from drewfish will help a ton!
https://github.com/drewfish/arduino-ZeroRegs(https://adafru.it/Bet)
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M4 Performance Options
As of version 1.4.0 of the Adafruit SAMD Boards package in the Arduino Boards
Manager, some options are available to wring extra performance out of M4-based
devices. These are in the Tools menu.
All of these performance tweaks involve a degree of uncertainty. There’s no
guarantee of improved performance in any given project, and some may even be
detrimental, failing to work in part or in whole. If you encounter trouble, select the
default performance settings and re-upload.
Here’s what you get and some issues you might encounter…
CPU Speed (overclocking)
This option lets you adjust the microcontroller core clock…the speed at which it
processes instructions…beyond the official datasheet specifications.
Manufacturers often rate speeds conservatively because such devices are marketed
for harsh industrial environments…if a system crashes, someone could lose a limb or
worse. But most creative tasks are less critical and operate in more comfortable
settings, and we can push things a bit if we want more speed.
There is a small but nonzero chance of code locking up or failing to run entirely. If this
happens, try dialing back the speed by one notch and re-upload, see if it’s more
stable.
Much more likely, some code or libraries may not play well with the nonstandard CPU
speed. For example, currently the NeoPixel library assumes a 120 MHz CPU speed
and won’t issue the correct data at other settings (this will be worked on). Other
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libraries may exhibit similar problems, usually anything that strictly depends on CPU
timing…you might encounter problems with audio- or servo-related code depending
how it’s written. If you encounter such code or libraries, set the CPU speed to the
default 120 MHz and re-upload.
Optimize
There’s usually more than one way to solve a problem, some more resource-intensive
than others. Since Arduino got its start on resource-limited AVR microcontrollers, the
C++ compiler has always aimed for the smallest compiled program size. The
“Optimize” menu gives some choices for the compiler to take different and often
faster approaches, at the expense of slightly larger program size…with the huge flash
memory capacity of M4 devices, that’s rarely a problem now.
The “Small” setting will compile your code like it always has in the past, aiming for the
smallest compiled program size.
The “Fast” setting invokes various speed optimizations. The resulting program should
produce the same results, is slightly larger, and usually (but not always) noticably
faster. It’s worth a shot!
“Here be dragons” invokes some more intensive optimizations…code will be larger
still, faster still, but there’s a possibility these optimizations could cause unexpected
behaviors. Some code may not work the same as before. Hence the name. Maybe
you’ll discover treasure here, or maybe you’ll sail right off the edge of the world.
Most code and libraries will continue to function regardless of the optimizer settings.
If you do encounter problems, dial it back one notch and re-upload.
Cache
This option allows a small collection of instructions and data to be accessed more
quickly than from flash memory, boosting performance. It’s enabled by default and
should work fine with all code and libraries. But if you encounter some esoteric
situation, the cache can be disabled, then recompile and upload.
Max SPI and Max QSPI
These should probably be left at their defaults. They’re present mostly for our own
experiments and can cause serious headaches.
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Max SPI determines the clock source for the M4’s SPI peripherals. Under normal
circumstances this allows transfers up to 24 MHz, and should usually be left at that
setting. But…if you’re using write-only SPI devices (such as TFT or OLED displays), this
option lets you drive them faster (we’ve successfully used 60 MHz with some TFT
screens). The caveat is, if using any read/write devices (such as an SD card), this will
not work at all…SPI readsabsolutely max out at the default 24 MHz setting, and
anything else will fail. Write = OK. Read = FAIL. This is true even if your code is using a
lower bitrate setting…just having the different clock source prevents SPI reads.
Max QSPI does similarly for the extra flash storage on M4 “Express” boards. Very few
Arduino sketches access this storage at all, let alone in a bandwidth-constrained
context, so this will benefit next to nobody. Additionally, due to the way clock dividers
are selected, this will only provide some benefit when certain “CPU Speed” settings
are active. Our PyPortal Animated GIF Display(https://adafru.it/EkO) runs marginally
better with it, if using the QSPI flash.
Enabling the Buck Converter on some M4 Boards
If you want to reduce power draw, some of our boards have an inductor so you can
use the 1.8V buck converter instead of the built in linear regulator. If the board does
have an inductor (see the schematic) you can add the line SUPC->VREG.bit.SEL =
1; to your code to switch to it. Note it will make ADC/DAC reads a bit noisier so we
don't use it by default. You'll save ~4mA(https://adafru.it/F0H).
What is CircuitPython?
CircuitPython is a programming language designed to simplify experimenting and
learning to program on low-cost microcontroller boards. It makes getting started
easier than ever with no upfront desktop downloads needed. Once you get your
board set up, open any text editor, and get started editing code. It's that simple.
©Adafruit Industries Page 39 of 211
CircuitPython is based on Python
Python is the fastest growing programming language. It's taught in schools and
universities. It's a high-level programming language which means it's designed to be
easier to read, write and maintain. It supports modules and packages which means it's
easy to reuse your code for other projects. It has a built in interpreter which means
there are no extra steps, like compiling, to get your code to work. And of course,
Python is Open Source Software which means it's free for anyone to use, modify or
improve upon.
CircuitPython adds hardware support to all of these amazing features. If you already
have Python knowledge, you can easily apply that to using CircuitPython. If you have
no previous experience, it's really simple to get started!
Why would I use CircuitPython?
CircuitPython is designed to run on microcontroller boards. A microcontroller board is
a board with a microcontroller chip that's essentially an itty-bitty all-in-one computer.
The board you're holding is a microcontroller board! CircuitPython is easy to use
because all you need is that little board, a USB cable, and a computer with a USB
connection. But that's only the beginning.
Other reasons to use CircuitPython include:
You want to get up and running quickly. Create a file, edit your code, save the
•
file, and it runs immediately. There is no compiling, no downloading and no
uploading needed.
You're new to programming. CircuitPython is designed with education in mind.
•
It's easy to start learning how to program and you get immediate feedback from
the board.
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Easily update your code. Since your code lives on the disk drive, you can edit it
•
whenever you like, you can also keep multiple files around for easy
experimentation.
The serial console and REPL. These allow for live feedback from your code and
•
interactive programming.
File storage. The internal storage for CircuitPython makes it great for data-
•
logging, playing audio clips, and otherwise interacting with files.
Strong hardware support. There are many libraries and drivers for sensors,
•
breakout boards and other external components.
It's Python! Python is the fastest-growing programming language. It's taught in
•
schools and universities. CircuitPython is almost-completely compatible with
Python. It simply adds hardware support.
This is just the beginning. CircuitPython continues to evolve, and is constantly being
updated. Adafruit welcomes and encourages feedback from the community, and
incorporate it into the development of CircuitPython. That's the core of the open
source concept. This makes CircuitPython better for you and everyone who uses it!
CircuitPython on ItsyBitsy
CircuitPython(https://adafru.it/tB7) is a derivative of MicroPython(https://adafru.it/BeZ)
designed to simplify experimentation and education on low-cost microcontrollers. It
makes it easier than ever to get prototyping by requiring no upfront desktop software
downloads. Simply copy and edit files on the CIRCUITPY drive to iterate.
Set up CircuitPython Quick Start!
Follow this quick step-by-step for super-fast Python power :)
Download the latest version of
CircuitPython for this board via
CircuitPython.org
https://adafru.it/Emj
Further Information
For more detailed info on installing CircuitPython, check out Installing CircuitPython(h
ttps://adafru.it/Amd).
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Click the link above and download the
latest UF2 file.
Download and save it to your desktop (or
wherever is handy).
Plug your Itsy M4 into your computer
using a known-good USB cable.
A lot of people end up using charge-only
USB cables and it is very frustrating! So
make sure you have a USB cable you
know is good for data sync.
Double-click the Reset button on your
board, and you will see the DotStar RGB
LED turn green. If it turns red, check the
USB cable, try another USB port, etc.
If double-clicking doesn't work the first
time, try again. Sometimes it can take a
few tries to get the rhythm right!
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You will see a new disk drive appear
called ITSYBOOT.
Drag the adafruit_circuitpython_etc.uf2
file to ITSYBOOT.
The LED will flash. Then, the ITSYBOOT
drive will disappear and a new disk drive
called CIRCUITPY will appear.
That's it, you're done! :)
Installing the Mu Editor
Mu is a simple code editor that works with the Adafruit CircuitPython boards. It's
written in Python and works on Windows, MacOS, Linux and Raspberry Pi. The serial
console is built right in so you get immediate feedback from your board's serial
output!
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Mu is our recommended editor - please use it (unless you are an experienced
coder with a favorite editor already!).
Download and Install Mu
Download Mu fromhttps://
codewith.mu(https://adafru.it/Be6).
Click theDownload link for downloads
and installation instructions.
Click Start Hereto find a wealth of other
information, including extensive tutorials
and and how-to's.
Windows users: due to the nature of MSI installers, please remove old versions of
Mu before installing the latest version.
Starting Up Mu
The first time you start Mu, you will be
prompted to select your 'mode' - you can
always change your mind later. For now
please select CircuitPython!
The current mode is displayed in the
lower right corner of the window, next to
the "gear" icon. If the mode says
"Microbit" or something else, click the
Mode button in the upper left, and then
choose "CircuitPython" in the dialog box
that appears.
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Mu attempts to auto-detect your board
on startup, so if you do not have a
CircuitPython board plugged in with a
CIRCUITPY drive available, Mu will inform
you where it will store any code you save
until you plug in a board.
To avoid this warning, plug in a board
and ensure that the CIRCUITPY drive is
mounted before starting Mu.
Using Mu
You can now explore Mu! The three main sections of the window are labeled below;
the button bar, the text editor, and the serial console / REPL.
Now you're ready to code! Let's keep going...
Creating and Editing Code
One of the best things about CircuitPython is how simple it is to get code up and
running. This section covers how to create and edit your first CircuitPython program.
To create and edit code, all you'll need is an editor. There are many options. Adafruit
strongly recommends using Mu! It's designed for CircuitPython, and it's really simple
and easy to use, with a built in serial console!
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If you don't or can't use Mu, there are a number of other editors that work quite well.
The Recommended Editors page(https://adafru.it/Vue) has more details. Otherwise,
make sure you do "Eject" or "Safe Remove" on Windows or "sync" on Linux after
writing a file if you aren't using Mu. (This is not a problem on MacOS.)
Creating Code
Installing CircuitPython generates a
code.py file on your CIRCUITPY drive. To
begin your own program, open your
editor, and load the code.py file from the
CIRCUITPY drive.
If you are using Mu, click the Load button
in the button bar, navigate to the
CIRCUITPY drive, and choose code.py.
Copy and paste the following code into your editor:
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
led.value = True
time.sleep(0.5)
led.value = False
time.sleep(0.5)
The KB2040, QT Py and the Trinkeys do not have a built-in little red LED! There is
an addressable RGB NeoPixel LED. The above example will NOT work on the
KB2040, QT Py or the Trinkeys!
If you're using a KB2040, QT Py or a Trinkey, please download the NeoPixel blink
example(https://adafru.it/UDU).
The NeoPixel blink example uses the onboard NeoPixel, but the time code is the
same. You can use the linked NeoPixel Blink example to follow along with this
guide page.
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It will look like this. Note that under the
while True: line, the next four lines
begin with four spaces to indent them,
and they're indented exactly the same
amount. All the lines before that have no
spaces before the text.
Save the code.py file on your CIRCUITPY
drive.
The little LED should now be blinking. Once per half-second.
Congratulations, you've just run your first CircuitPython program!
On most boards you'll find a tiny red LED.
On the ItsyBitsy nRF52840, you'll find a tiny blue LED.
On QT Py M0, QT Py RP2040, and the Trinkey series, you will find only an RGB
NeoPixel LED.
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Editing Code
To edit code, open thecode.pyfile on
your CIRCUITPY drive into your editor.
Make the desired changes to your code.
Save the file. That's it!
Your code changes are run as soon as the file is done saving.
There's one warning before you continue...
Don't click reset or unplug your board!
The CircuitPython code on your board detects when the files are changed or written
and will automatically re-start your code. This makes coding very fast because you
save, and it re-runs. If you unplug or reset the board before your computer finishes
writing the file to your board, you can corrupt the drive. If this happens, you may lose
the code you've written, so it's important to backup your code to your computer
regularly.
There are a couple of ways to avoid filesystem corruption.
1. Use an editor that writes out the file completely when you save it.
Check out the Recommended Editors page(https://adafru.it/Vue) for details on
different editing options.
If you are dragging a file from your host computer onto the CIRCUITPY drive, you
still need to do step 2. Eject or Sync (below) to make sure the file is completely
written.
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2. Eject or Sync the Drive After Writing
If you are using one of our not-recommended-editors, not all is lost! You can still make
it work.
On Windows, you can Eject or Safe Remove the CIRCUITPY drive. It won't actually
eject, but it will force the operating system to save your file to disk. On Linux, use the
sync command in a terminal to force the write to disk.
You also need to do this if you use Windows Explorer or a Linux graphical file
manager to drag a file onto CIRCUITPY.
Oh No I Did Something Wrong and Now The CIRCUITPY Drive Doesn't Show Up!!!
Don't worry! Corrupting the drive isn't the end of the world (or your board!). If this
happens, follow the steps found on the Troubleshooting(https://adafru.it/Den) page
of every board guide to get your board up and running again.
Back to Editing Code...
Now! Let's try editing the program you added to your board. Open your code.py file
into your editor. You'll make a simple change. Change the first 0.5 to 0.1 . The code
should look like this:
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
led.value = True
time.sleep(0.1)
led.value = False
time.sleep(0.5)
Leave the rest of the code as-is. Save your file. See what happens to the LED on your
board? Something changed! Do you know why?
You don't have to stop there! Let's keep going. Change the second 0.5 to 0.1 so it
looks like this:
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while True:
led.value = True
time.sleep(0.1)
led.value = False
time.sleep(0.1)
Now it blinks really fast! You decreased the both time that the code leaves the LED on
and off!
Now try increasing both of the 0.1 to 1 . Your LED will blink much more slowly
because you've increased the amount of time that the LED is turned on and off.
Well done! You're doing great! You're ready to start into new examples and edit them
to see what happens! These were simple changes, but major changes are done using
the same process. Make your desired change, save it, and get the results. That's
really all there is to it!
Naming Your Program File
CircuitPython looks for a code file on the board to run. There are four options: code.t
xt, code.py, main.txt and main.py. CircuitPython looks for those files, in that order, and
then runs the first one it finds. While code.py is the recommended name for your code
file, it is important to know that the other options exist. If your program doesn't seem
to be updating as you work, make sure you haven't created another code file that's
being read instead of the one you're working on.
Connecting to the Serial Console
One of the staples of CircuitPython (and programming in general!) is something called
a "print statement". This is a line you include in your code that causes your code to
output text. A print statement in CircuitPython (and Python) looks like this:
print("Hello, world!")
This line in your code.py would result in:
Hello, world!
However, these print statements need somewhere to display. That's where the serial
console comes in!
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The serial console receives output from your CircuitPython board sent over USB and
displays it so you can see it. This is necessary when you've included a print statement
in your code and you'd like to see what you printed. It is also helpful for
troubleshooting errors, because your board will send errors and the serial console will
display those too.
The serial console requires an editor that has a built in terminal, or a separate
terminal program. A terminal is a program that gives you a text-based interface to
perform various tasks.
Are you using Mu?
If so, good news! The serial consoleis built into Mu and willautodetect your board
making using the serial console really really easy.
First, make sure your CircuitPython board
is plugged in.
If you open Mu without a board plugged
in, you may encounter the error seen
here, letting you know no CircuitPython
board was found and indicating where
your code will be stored until you plug in
a board.
If you are using Windows 7, make sure
you installed the drivers(https://adafru.it/
VuB).
Once you've opened Mu with your board plugged in, look for the Serial button in the
button bar and click it.
The Mu window will split in two, horizontally, and display the serial console at the
bottom.
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If nothing appears in the serial console, it may mean your code is done running
or has no print statements in it. Click into the serial console part of Mu, and press
CTRL+D to reload.
Serial Console Issues or Delays on Linux
If you're on Linux, and are seeing multi-second delays connecting to the serial
console, or are seeing "AT" and other gibberish when you connect, then the modemma
nager service might be interfering. Just remove it; it doesn't have much use unless
you're still using dial-up modems.
To remove modemmanager , type the following command at a shell:
sudo apt purge modemmanager
Setting Permissions on Linux
On Linux, if you see an error box something like the one below when you press the S
erial button, you need to add yourself to a user group to have permission to connect
to the serial console.
On Ubuntu and Debian, add yourself to the dialout group by doing:
sudo adduser $USER dialout
After running the command above, reboot your machine to gain access to the group.
On other Linux distributions, the group you need may be different. See the Advanced
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Serial Console on Linux(https://adafru.it/VAO)for details on how to add yourself to
the right group.
Using Something Else?
If you're not using Mu to edit, are using or if for some reason you are not a fan of its
built in serial console, you can run the serial console from a separate program.
Windows requires you to download a terminal program. Check out the Advanced
Serial Console on Windows page for more details.(https://adafru.it/AAH)
MacOS has Terminal built in, though there are other options available for download. C
heck the Advanced Serial Console on Mac page for more details.(https://adafru.it/
AAI)
Linux has a terminal program built in, though other options are available for
download. Check the Advanced Serial Console on Linux page for more details.(https:
//adafru.it/VAO)
Once connected, you'll see something like the following.
Interacting with the Serial Console
Once you've successfully connected to the serial console, it's time to start using it.
The code you wrote earlier has no output to the serial console. So, you're going to
edit it to create some output.
Open your code.py file into your editor, and include a print statement. You can print
anything you like! Just include your phrase between the quotation marks inside the
parentheses. For example:
import board
import digitalio
import time
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led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello, CircuitPython!")
led.value = True
time.sleep(1)
led.value = False
time.sleep(1)
Save your file.
Now, let's go take a look at the window with our connection to the serial console.
Excellent! Our print statement is showing up in our console! Try changing the printed
text to something else.
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello back to you!")
led.value = True
time.sleep(1)
led.value = False
time.sleep(1)
Keep your serial console window where you can see it. Save your file. You'll see what
the serial console displays when the board reboots. Then you'll see your new change!
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The Traceback (most recent call last): is telling you the last thing your board
was doing before you saved your file. This is normal behavior and will happen every
time the board resets. This is really handy for troubleshooting. Let's introduce an error
so you can see how it is used.
Delete the e at the end of True from the line led.value = True so that it says le
d.value = Tru
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello back to you!")
led.value = Tru
time.sleep(1)
led.value = False
time.sleep(1)
Save your file. You will notice that your red LED will stop blinking, and you may have a
colored status LED blinking at you. This is because the code is no longer correct and
can no longer run properly. You need to fix it!
Usually when you run into errors, it's not because you introduced them on purpose.
You may have 200 lines of code, and have no idea where your error could be hiding.
This is where the serial console can help. Let's take a look!
The Traceback (most recent call last): is telling you that the last thing it was
able to run was line 10 in your code. The next line is your error: NameError: name
'Tru' is not defined . This error might not mean a lot to you, but combined with
knowing the issue is on line 10, it gives you a great place to start!
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Go back to your code, and take a look at line 10. Obviously, you know what the
problem is already. But if you didn't, you'd want to look at line 10 and see if you could
figure it out. If you're still unsure, try googling the error to get some help. In this case,
you know what to look for. You spelled True wrong. Fix the typo and save your file.
Nice job fixing the error! Your serial console is streaming and your red LED Is blinking
again.
The serial console will display any output generated by your code. Some sensors,
such as a humidity sensor or a thermistor, receive data and you can use print
statements to display that information. You can also use print statements for
troubleshooting, which is called "print debugging". Essentially, if your code isn't
working, and you want to know where it's failing, you can put print statements in
various places to see where it stops printing.
The serial console has many uses, and is an amazing tool overall for learning and
programming!
The REPL
The other feature of the serial connection is the Read-Evaluate-Print-Loop, or REPL.
The REPL allows you to enter individual lines of code and have them run immediately.
It's really handy if you're running into trouble with a particular program and can't
figure out why. It's interactive so it's great for testing new ideas.
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Entering the REPL
To use the REPL, you first need to be connected to the serial console. Once that
connection has been established, you'll want to press CTRL+C.
If there is code running, in this case code measuring distance, it will stop and you'll
see Press any key to enter the REPL. Use CTRL-D to reload. Follow those
instructions, and press any key on your keyboard.
The Traceback (most recent call last): is telling you the last thing your board
was doing before you pressed Ctrl + C and interrupted it. The KeyboardInterrupt
is you pressing CTRL+C. This information can be handy when troubleshooting, but for
now, don't worry about it. Just note that it is expected behavior.
If your code.py file is empty or does not contain a loop, it will show an empty output
and Code done running. . There is no information about what your board was
doing before you interrupted it because there is no code running.
If you have no code.py on your CIRCUITPY drive, you will enter the REPL immediately
after pressing CTRL+C. Again, there is no information about what your board was
doing before you interrupted it because there is no code running.
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Regardless, once you press a key you'll see a >>> prompt welcoming you to the
REPL!
If you have trouble getting to the >>> prompt, try pressing Ctrl + C a few more times.
The first thing you get from the REPL is information about your board.
This line tells you the version of CircuitPython you're using and when it was released.
Next, it gives you the type of board you're using and the type of microcontroller the
board uses. Each part of this may be different for your board depending on the
versions you're working with.
This is followed by the CircuitPython prompt.
Interacting with the REPL
From this prompt you can run all sorts of commands and code. The first thing you'll do
is run help() . This will tell you where to start exploring the REPL. To run code in the
REPL, type it in next to the REPL prompt.
Type help() next to the prompt in the REPL.
Then press enter. You should then see a message.
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First part of the message is another reference to the version of CircuitPython you're
using. Second, a URL for the CircuitPython related project guides. Then... wait. What's
this? To list built-in modules type `help("modules")`. Remember the
modules you learned about while going through creating code? That's exactly what
this is talking about! This is a perfect place to start. Let's take a look!
Type help("modules") into the REPL next to the prompt, and press enter.
This is a list of all the core modules built into CircuitPython, including board .
Remember, board contains all of the pins on the board that you can use in your
code. From the REPL, you are able to see that list!
Type import board into the REPL and press enter. It'll go to a new prompt. It might
look like nothing happened, but that's not the case! If you recall, the import
statement simply tells the code to expect to do something with that module. In this
case, it's telling the REPL that you plan to do something with that module.
Next, type dir(board) into the REPL and press enter.
This is a list of all of the pins on your board that are available for you to use in your
code. Each board's list will differ slightly depending on the number of pins available.
Do you see LED ? That's the pin you used to blink the red LED!
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The REPL can also be used to run code. Be aware that any code you enter into the
REPL isn't saved anywhere. If you're testing something new that you'd like to keep,
make sure you have it saved somewhere on your computer as well!
Every programmer in every programming language starts with a piece of code that
says, "Hello, World." You're going to say hello to something else. Type into the REPL:
print("Hello, CircuitPython!")
Then press enter.
That's all there is to running code in the REPL! Nice job!
You can write single lines of code that run stand-alone. You can also write entire
programs into the REPL to test them. Remember that nothing typed into the REPL is
saved.
There's a lot the REPL can do for you. It's great for testing new ideas if you want to
see if a few new lines of code will work. It's fantastic for troubleshooting code by
entering it one line at a time and finding out where it fails. It lets you see what
modules are available and explore those modules.
Try typing more into the REPL to see what happens!
Everything typed into the REPL is ephemeral. Once you reload the REPL or return
to the serial console, nothing you typed will be retained in any memory space. So
be sure to save any desired code you wrote somewhere else, or you'll lose it
when you leave the current REPL instance!
Returning to the Serial Console
When you're ready to leave the REPL and return to the serial console, simply press CT
RL+D. This will reload your board and reenter the serial console. You will restart the
program you had running before entering the REPL. In the console window, you'll see
any output from the program you had running. And if your program was affecting
anything visual on the board, you'll see that start up again as well.
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You can return to the REPL at any time!
CircuitPython Libraries
As CircuitPython development continues and there are new releases, Adafruit
will stop supporting older releases. Visit https://circuitpython.org/downloads 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 https://circuitpython.org/libraries to
download the latest Library Bundle.
Each CircuitPython program you run needs to have a lot of information to work. The
reason CircuitPython is so simple to use is that most of that information is stored in
other files and works in the background. These files are called libraries. Some of them
are built into CircuitPython. Others are stored on your CIRCUITPY drive in a folder
called lib. Part of what makes CircuitPython so great is its ability to store code
separately from the firmware itself. Storing code separately from the firmware makes
it easier to update both the code you write and the libraries you depend.
Your board may ship with a lib folder already, it's in the base directory of the drive. If
not, simply create the folder yourself. When you first install CircuitPython, an empty lib
directory will be created for you.
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CircuitPython libraries work in the same way as regular Python modules so the Python
docs(https://adafru.it/rar) are an excellent reference for how it all should work. In
Python terms, you can place our library files in the lib directory because it's part of the
Python path by default.
One downside of this approach of separate libraries is that they are not built in. To
use them, one needs to copy them to the CIRCUITPY drive before they can be used.
Fortunately, there is a library bundle.
The bundle and the library releases on GitHub also feature optimized versions of the
libraries with the .mpy file extension. These files take less space on the drive and
have a smaller memory footprint as they are loaded.
Due to the regular updates and space constraints, Adafruit does not ship boards with
the entire bundle. Therefore, you will need to load the libraries you need when you
begin working with your board. You can find example code in the guides for your
board that depends on external libraries.
Either way, as you start to explore CircuitPython, you'll want to know how to get
libraries on board.
The Adafruit CircuitPython Library Bundle
Adafruit provides CircuitPython libraries for much of the hardware they provide,
including sensors, breakouts and more. To eliminate the need for searching for each
library individually, the libraries are available together in the Adafruit CircuitPython
Library Bundle. The bundle contains all the files needed to use each library.
Downloading the Adafruit CircuitPython Library Bundle
You can download the latest Adafruit CircuitPython Library Bundle release by clicking
the button below. The libraries are being constantly updated and improved, so you'll
always want to download the latest bundle.
Match up the bundle version with the version of CircuitPython you are running. For
example, you would download the 6.x library bundle if you're running any version of
CircuitPython 6, or the 7.x library bundle if you're running any version of CircuitPython
7, etc. If you mix libraries with major CircuitPython versions, you will get incompatible
mpy errors due to changes in library interfaces possible during major version
changes.
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Click to visit circuitpython.org for the
latest Adafruit CircuitPython Library
Bundle
https://adafru.it/ENC
Download the bundle version that matches your CircuitPython firmware version. If you
don't know the version, check the version info in boot_out.txt file on the CIRCUITPY
drive, or the initial prompt in the CircuitPython REPL. For example, if you're running
v7.0.0, download the 7.x library bundle.
There's also a py bundle which contains the uncompressed python files, you probably
don't want that unless you are doing advanced work on libraries.
The CircuitPython Community Library Bundle
The CircuitPython Community Library Bundle is made up of libraries written and
provided by members of the CircuitPython community. These libraries are often
written when community members encountered hardware not supported in the
Adafruit Bundle, or to support a personal project. The authors all chose to submit
these libraries to the Community Bundle make them available to the community.
These libraries are maintained by their authors and are not supported by Adafruit. As
you would with any library, if you run into problems, feel free to file an issue on the
GitHub repo for the library. Bear in mind, though, that most of these libraries are
supported by a single person and you should be patient about receiving a response.
Remember, these folks are not paid by Adafruit, and are volunteering their personal
time when possible to provide support.
Downloading the CircuitPython Community Library Bundle
You can download the latest CircuitPython Community Library Bundle release by
clicking the button below. The libraries are being constantly updated and improved,
so you'll always want to download the latest bundle.
Click for the latest CircuitPython
Community Library Bundle release
https://adafru.it/VCn
The link takes you to the latest release of the CircuitPython Community Library
Bundle on GitHub. There are multiple versions of the bundle available. Download the
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bundle version that matches your CircuitPython firmware version. If you don't know
the version, check the version info in boot_out.txt file on the CIRCUITPY drive, or the
initial prompt in the CircuitPython REPL. For example, if you're running v7.0.0,
download the 7.x library bundle.
Understanding the Bundle
After downloading the zip, extract its contents. This is usually done by double clicking
on the zip. On Mac OSX, it places the file in the same directory as the zip.
Open the bundle folder. Inside you'll find two information files, and two folders. One
folder is the lib bundle, and the other folder is the examples bundle.
Now open the lib folder. When you open the folder, you'll see a large number of .mpy
files, and folders.
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Example Files
All example files from each library are now included in the bundles in an examples
directory (as seen above), as well as an examples-only bundle. These are included for
two main reasons:
Allow for quick testing of devices.
•
Provide an example base of code, that is easily built upon for individualized
•
purposes.
Copying Libraries to Your Board
First open the lib folder on your CIRCUITPY drive. Then, open the lib folder you
extracted from the downloaded zip. Inside you'll find a number of folders and .mpy
files. Find the library you'd like to use, and copy it to the lib folder on CIRCUITPY.
If the library is a directory with multiple .mpy files in it, be sure to copy the entire
folder to CIRCUITPY/lib.
This also applies to example files. Open the examples folder you extracted from the
downloaded zip, and copy the applicable file to your CIRCUITPY drive. Then, rename
it to code.py to run it.
If a library has multiple .mpy files contained in a folder, be sure to copy the entire
folder to CIRCUITPY/lib.
Understanding Which Libraries to Install
You now know how to load libraries on to your CircuitPython-compatible
microcontroller board. You may now be wondering, how do you know which libraries
you need to install? Unfortunately, it's not always straightforward. Fortunately, there is
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an obvious place to start, and a relatively simple way to figure out the rest. First up:
the best place to start.
When you look at most CircuitPython examples, you'll see they begin with one or
more import statements. These typically look like the following:
import library_or_module
•
However, import statements can also sometimes look like the following:
from library_or_module import name
•
from library_or_module.subpackage import name
•
from library_or_module import name as local_name
•
They can also have more complicated formats, such as including a try / except
block, etc.
The important thing to know is that an import statement will always include the
name of the module or library that you're importing.
Therefore, the best place to start is by reading through the import statements.
Here is an example import list for you to work with in this section. There is no setup or
other code shown here, as the purpose of this section involves only the import list.
import time
import board
import neopixel
import adafruit_lis3dh
import usb_hid
from adafruit_hid.consumer_control import ConsumerControl
from adafruit_hid.consumer_control_code import ConsumerControlCode
Keep in mind, not all imported items are libraries. Some of them are almost always
built-in CircuitPython modules. How do you know the difference? Time to visit the
REPL.
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In the Interacting with the REPL section(https://adafru.it/Awz) on The REPL page(http
s://adafru.it/Awz) in this guide, the help("modules") command is discussed. This
command provides a list of all of the built-in modules available in CircuitPython for
your board. So, if you connect to the serial console on your board, and enter the
REPL, you can run help("modules") to see what modules are available for your
board. Then, as you read through the import statements, you can, for the purposes
of figuring out which libraries to load, ignore the statement that import modules.
The following is the list of modules built into CircuitPython for the Feather RP2040.
Your list may look similar or be anything down to a significant subset of this list for
smaller boards.
Now that you know what you're looking for, it's time to read through the import
statements. The first two, time and board , are on the modules list above, so they're
built-in.
The next one, neopixel , is not on the module list. That means it's your first library!
So, you would head over to the bundle zip you downloaded, and search for neopixel.
There is a neopixel.mpy file in the bundle zip. Copy it over to the lib folder on your CI
RCUITPY drive. The following one, adafruit_lis3dh , is also not on the module list.
Follow the same process for adafruit_lis3dh, where you'll find adafruit_lis3dh.mpy,
and copy that over.
The fifth one is usb_hid , and it is in the modules list, so it is built in. Often all of the
built-in modules come first in the import list, but sometimes they don't! Don't assume
that everything after the first library is also a library, and verify each import with the
modules list to be sure. Otherwise, you'll search the bundle and come up empty!
The final two imports are not as clear. Remember, when import statements are
formatted like this, the first thing after the from is the library name. In this case, the
library name is adafruit_hid . A search of the bundle will find an adafruit_hid folder.
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When a library is a folder, you must copy the entire folder and its contentsas it is in
the bundle to the lib folder on your CIRCUITPY drive. In this case, you would copy the
entire adafruit_hid folder to your CIRCUITPY/lib folder.
Notice that there are two imports that begin with adafruit_hid . Sometimes you will
need to import more than one thing from the same library. Regardless of how many
times you import the same library, you only need to load the library by copying over
the adafruit_hid folder once.
That is how you can use your example code to figure out what libraries to load on
your CircuitPython-compatible board!
There are cases, however, where libraries require other libraries internally. The
internally required library is called a dependency. In the event of library
dependencies, the easiest way to figure out what other libraries are required is to
connect to the serial console and follow along with the ImportError printed there.
The following is a very simple example of an ImportError , but the concept is the
same for any missing library.
Example: ImportError Due to Missing Library
If you choose to load libraries as you need them, or you're starting fresh with an
existing example, you may end up with code that tries to use a library you haven't yet
loaded. This section will demonstrate what happens when you try to utilise a library
that you don't have loaded on your board, and cover the steps required to resolve the
issue.
This demonstration will only return an error if you do not have the required library
loaded into the lib folder on your CIRCUITPY drive.
Let's use a modified version of the Blink example.
import board
import time
import simpleio
led = simpleio.DigitalOut(board.LED)
while True:
led.value = True
time.sleep(0.5)
led.value = False
time.sleep(0.5)
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Save this file. Nothing happens to your board. Let's check the serial console to see
what's going on.
You have an ImportError . It says there is no module named 'simpleio' . That's
the one you just included in your code!
Click the link above to download the correct bundle. Extract the lib folder from the
downloaded bundle file. Scroll down to find simpleio.mpy. This is the library file you're
looking for! Follow the steps above to load an individual library file.
The LED starts blinking again! Let's check the serial console.
No errors! Excellent. You've successfully resolved an ImportError !
If you run into this error in the future, follow along with the steps above and choose
the library that matches the one you're missing.
Library Install on Non-Express Boards
If you have an M0 non-Express board such as Trinket M0, Gemma M0, QT Py M0, or
one of the M0 Trinkeys, you'll want to follow the same steps in the example above to
install libraries as you need them. Remember, you don't need to wait for an ImportE
rror if you know what library you added to your code. Open the library bundle you
downloaded, find the library you need, and drag it to the lib folder on your CIRCUITPY
drive.
You can still end up running out of space on your M0 non-Express board even if you
only load libraries as you need them. There are a number of steps you can use to try
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to resolve this issue. You'll find suggestions on the Troubleshooting page(https://
adafru.it/Den).
Updating CircuitPython Libraries and Examples
Libraries and examples are updated from time to time, and it's important to update the
files you have on your CIRCUITPY drive.
To update a single library or example, follow the same steps above. When you drag
the library file to your lib folder, it will ask if you want to replace it. Say yes. That's it!
A new library bundle is released every time there's an update to a library. Updates
include things like bug fixes and new features. It's important to check in every so
often to see if the libraries you're using have been updated.
Frequently Asked Questions
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 https://circuitpython.org/downloads 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 https://circuitpython.org/libraries to
download the latest Library Bundle.
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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(https://adafru.it/Em8) and use the current version of the libraries(https://
adafru.it/ENC). However, if for some reason you cannot update, here are the last
available library bundles for older versions:
2.x bundle(https://adafru.it/FJA)
•
3.x bundle(https://adafru.it/FJB)
•
4.x bundle(https://adafru.it/QDL)
•
5.x bundle(https://adafru.it/QDJ)
•
6.x bundle(https://adafru.it/Xmf)
•
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(https://adafru.it/CiG)!
We do not support ESP32 because it does not have native USB.
We do support ESP32-S2, which has native USB.
How do I connect to the Internet with CircuitPython?
If you'd like to include WiFi in your project, check out this guide(https://adafru.it/
F5X) on using AirLift with CircuitPython. For further project examples, and guides
about using AirLift with specific hardware, check out the Adafruit Learn
System(https://adafru.it/VBr).
Is there asyncio support in CircuitPython?
There is preliminary support for asyncio starting with CircuitPython 7.1.0. Read
about using it in the Cooperative Multitasking in CircuitPython(https://adafru.it/
XnA) Guide.
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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!(https://adafru.it/Den)
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(https://adafru.it/uap) 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 code.py. 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.
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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(https://
adafru.it/QDK). 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/yourfile.py 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
gc.mem_free()
Does CircuitPython support interrupts?
No. CircuitPython does not currently support interrupts. We do not have an
estimated time for when they will be included
Does Feather M0 support WINC1500?
No, WINC1500 will not fit into the M0 flash space.
Can AVRs such as ATmega328 or ATmega2560 run CircuitPython?
No.
Commonly Used Acronyms
CP or CPy = CircuitPython(https://adafru.it/KJD)
CPC = Circuit Playground Classic(https://adafru.it/ncE)
CPX = Circuit Playground Express(https://adafru.it/wpF)
CPB = Circuit Playground Bluefruit(https://adafru.it/Gpe)
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Welcome to the Community!
CircuitPython is a programming language that's super simple to get started with and
great for learning. It runs on microcontrollers and works out of the box. You can plug it
in and get started with any text editor. The best part? CircuitPython comes with an
amazing, supportive community.
Everyone is welcome! CircuitPython is Open Source. This means it's available for
anyone to use, edit, copy and improve upon. This also means CircuitPython becomes
better because of you being a part of it. Whether this is your first microcontroller
board or you're a seasoned software engineer, you have something important to offer
the Adafruit CircuitPython community. This page highlights some of the many ways
you can be a part of it!
Adafruit Discord
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The Adafruit Discord server is the best place to start. Discord is where the community
comes together to volunteer and provide live support of all kinds. From general
discussion to detailed problem solving, and everything in between, Discord is a digital
maker space with makers from around the world.
There are many different channels so you can choose the one best suited to your
needs. Each channel is shown on Discord as "#channelname". There's the #help-withprojects channel for assistance with your current project or help coming up with ideas
for your next one. There's the #show-and-tell channel for showing off your newest
creation. Don't be afraid to ask a question in any channel! If you're unsure, #general is
a great place to start. If another channel is more likely to provide you with a better
answer, someone will guide you.
The help with CircuitPython channel is where to go with your CircuitPython questions.
#help-with-circuitpython is there for new users and developers alike so feel free to
ask a question or post a comment! Everyone of any experience level is welcome to
join in on the conversation. Your contributions are important! The #circuitpython-dev
channel is available for development discussions as well.
The easiest way to contribute to the community is to assist others on Discord.
Supporting others doesn't always mean answering questions. Join in celebrating
successes! Celebrate your mistakes! Sometimes just hearing that someone else has
gone through a similar struggle can be enough to keep a maker moving forward.
The Adafruit Discord is the 24x7x365 hackerspace that you can bring your
granddaughter to.
Visit https://adafru.it/discord ()to sign up for Discord. Everyone is looking forward to
meeting you!
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CircuitPython.org
Beyond the Adafruit Learn System, which you are viewing right now, the best place to
find information about CircuitPython is circuitpython.org(https://adafru.it/KJD).
Everything you need to get started with your new microcontroller and beyond is
available. You can do things like download CircuitPython for your microcontroller(htt
ps://adafru.it/Em8) or download the latest CircuitPython Library bundle(https://
adafru.it/ENC), or check out which single board computers support Blinka(https://
adafru.it/EA8). You can also get to various other CircuitPython related things like
Awesome CircuitPython or the Python for Microcontrollers newsletter. This is all
incredibly useful, but it isn't necessarily community related. So why is it included
here? The Contributing page(https://adafru.it/VD7).
CircuitPython itself is written in C. However, all of the Adafruit CircuitPython libraries
are written in Python. If you're interested in contributing to CircuitPython on the
Python side of things, check out circuitpython.org/contributing(https://adafru.it/VD7).
You'll find information pertaining to every Adafruit CircuitPython library GitHub
repository, giving you the opportunity to join the community by finding a contributing
option that works for you.
Note the date on the page next to Current Status for:
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If you submit any contributions to the libraries, and do not see them reflected on the
Contributing page, it could be that the job that checks for new updates hasn't yet run
for today. Simply check back tomorrow!
Now, a look at the different options.
Pull Requests
The first tab you'll find is a list of open pull requests.
GitHub pull requests, or PRs, are opened when folks have added something to an
Adafruit CircuitPython library GitHub repo, and are asking for Adafruit to add, or
merge, their changes into the main library code. For PRs to be merged, they must first
be reviewed. Reviewing is a great way to contribute! Take a look at the list of open
pull requests, and pick one that interests you. If you have the hardware, you can test
code changes. If you don't, you can still check the code updates for syntax. In the
case of documentation updates, you can verify the information, or check it for spelling
and grammar. Once you've checked out the update, you can leave a comment letting
us know that you took a look. Once you've done that for a while, and you're more
comfortable with it, you can consider joining the CircuitPythonLibrarians review team.
The more reviewers we have, the more authors we can support. Reviewing is a crucial
part of an open source ecosystem, CircuitPython included.
Open Issues
The second tab you'll find is a list of open issues.
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GitHub issues are filed for a number of reasons, including when there is a bug in the
library or example code, or when someone wants to make a feature request. Issues
are a great way to find an opportunity to contribute directly to the libraries by
updating code or documentation. If you're interested in contributing code or
documentation, take a look at the open issues and find one that interests you.
If you're not sure where to start, you can search the issues by label. Labels are
applied to issues to make the goal easier to identify at a first glance, or to indicate the
difficulty level of the issue. Click on the dropdown next to "Sort by issue labels" to see
the list of available labels, and click on one to choose it.
If you're new to everything, new to contributing to open source, or new to
contributing to the CircuitPython project, you can choose "Good first issue". Issues
with that label are well defined, with a finite scope, and are intended to be easy for
someone new to figure out.
If you're looking for something a little more complicated, consider "Bug" or
"Enhancement". The Bug label is applied to issues that pertain to problems or failures
found in the library. The Enhancement label is applied to feature requests.
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Don't let the process intimidate you. If you're new to Git and GitHub, there is a guide(
https://adafru.it/Dkh) to walk you through the entire process. As well, there are always
folks available on Discord() to answer questions.
Library Infrastructure Issues
The third tab you'll find is a list of library infrastructure issues.
This section is generated by a script that runs checks on the libraries, and then
reports back where there may be issues. It is made up of a list of subsections each
containing links to the repositories that are experiencing that particular issue. This
page is available mostly for internal use, but you may find some opportunities to
contribute on this page. If there's an issue listed that sounds like something you could
help with, mention it on Discord, or file an issue on GitHub indicating you're working
to resolve that issue. Others can reply either way to let you know what the scope of it
might be, and help you resolve it if necessary.
CircuitPython Localization
The fourth tab you'll find is the CircuitPython Localization tab.
If you speak another language, you can help translate CircuitPython! The translations
apply to informational and error messages that are within the CircuitPython core. It
means that folks who do not speak English have the opportunity to have these
messages shown to them in their own language when using CircuitPython. This is
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incredibly important to provide the best experience possible for all users.
CircuitPython uses Weblate to translate, which makes it much simpler to contribute
translations. You will still need to know some CircuitPython-specific practices and a
few basics about coding strings, but as with any CircuitPython contributions, folks are
there to help.
Regardless of your skill level, or how you want to contribute to the CircuitPython
project, there is an opportunity available. The Contributing page(https://adafru.it/VD7)
is an excellent place to start!
Adafruit GitHub
Whether you're just beginning or are life-long programmer who would like to
contribute, there are ways for everyone to be a part of the CircuitPython project. The
CircuitPython core is written in C. The libraries are written in Python. GitHub is the
best source of ways to contribute to the CircuitPython core(https://adafru.it/tB7), and
the CircuitPython libraries(https://adafru.it/VFv). If you need an account, visit https://
github.com/(https://adafru.it/d6C)and sign up.
If you're new to GitHub or programming in general, there are great opportunities for
you. For the CircuitPython core, head over to the CircuitPython repository on GitHub,
click on "Issues(https://adafru.it/tBb)", and you'll find a list that includes issues labeled
"good first issue(https://adafru.it/Bef)". For the libraries, head over to the Contributing
page Issues list(https://adafru.it/VFv), and use the drop down menu to search for "go
od first issue(https://adafru.it/VFw)". These issues are things that have been identified
as something that someone with any level of experience can help with. These issues
include options like updating documentation, providing feedback, and fixing simple
bugs. If you need help getting started with GitHub, there is an excellent guide on Con
tributing to CircuitPython with Git and GitHub(https://adafru.it/Dkh).
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Already experienced and looking for a challenge? Checkout the rest of either issues
list and you'll find plenty of ways to contribute. You'll find all sorts of things, from new
driver requests, to library bugs, to core module updates. There's plenty of
opportunities for everyone at any level!
When working with or using CircuitPython or the CircuitPython libraries, you may find
problems. If you find a bug, that's great! The team loves bugs! Posting a detailed issue
to GitHub is an invaluable way to contribute to improving CircuitPython. For
CircuitPython itself, file an issue here(https://adafru.it/tBb). For the libraries, file an
issue on the specific library repository on GitHub. Be sure to include the steps to
replicate the issue as well as any other information you think is relevant. The more
detail, the better!
Testing new software is easy and incredibly helpful. Simply load the newest version of
CircuitPython or a library onto your CircuitPython hardware, and use it. Let us know
about any problems you find by posting a new issue to GitHub. Software testing on
both stable and unstable releases is a very important part of contributing
CircuitPython. The developers can't possibly find all the problems themselves! They
need your help to make CircuitPython even better.
On GitHub, you can submit feature requests, provide feedback, report problems and
much more. If you have questions, remember that Discord and the Forums are both
there for help!
Adafruit Forums
The Adafruit Forums(https://adafru.it/jIf) are the perfect place for support. Adafruit
has wonderful paid support folks to answer any questions you may have. Whether
your hardware is giving you issues or your code doesn't seem to be working, the
forums are always there for you to ask. You need an Adafruit account to post to the
forums. You can use the same account you use to order from Adafruit.
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While Discord may provide you with quicker responses than the forums, the forums
are a more reliable source of information. If you want to be certain you're getting an
Adafruit-supported answer, the forums are the best place to be.
There are forum categories that cover all kinds of topics, including everything
Adafruit. The Adafruit CircuitPython(https://adafru.it/xXA)category under "Supported
Products & Projects" is the best place to post your CircuitPython questions.
Be sure to include the steps you took to get to where you are. If it involves wiring,
post a picture! If your code is giving you trouble, include your code in your post!
These are great ways to make sure that there's enough information to help you with
your issue.
You might think you're just getting started, but you definitely know something that
someone else doesn't. The great thing about the forums is that you can help others
too! Everyone is welcome and encouraged to provide constructive feedback to any of
the posted questions. This is an excellent way to contribute to the community and
share your knowledge!
Read the Docs
Read the Docs(https://adafru.it/Beg) is a an excellent resource for a more detailed
look at the CircuitPython core and the CircuitPython libraries. This is where you'll find
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things like API documentation and example code. For an in depth look at viewing and
understanding Read the Docs, check out the CircuitPython Documentation(https://
adafru.it/VFx) page!
Advanced Serial Console on Windows
Windows 7 and 8.1
If you're using Windows 7 (or 8 or 8.1), you'll need to install drivers. See the Windows 7
and 8.1 Drivers page(https://adafru.it/VuB) for details. You will not need to install
drivers on Mac, Linux or Windows 10.
You are strongly encouraged to upgrade to Windows 10 if you are still using Windows
7 or Windows 8 or 8.1. Windows 7 has reached end-of-life and no longer receives
security updates. A free upgrade to Windows 10 is still available(https://adafru.it/
RWc).
What's the COM?
First, you'll want to find out which serial port your board is using. When you plug your
board in to USB on your computer, it connects to a serial port. The port is like a door
through which your board can communicate with your computer using USB.
You'll use Windows Device Manager to determine which port the board is using. The
easiest way to determine which port the board is using is to first check without the
board plugged in. Open Device Manager. Click on Ports (COM & LPT). You should find
something already in that list with (COM#) after it where # is a number.
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Now plug in your board. The Device Manager list will refresh and a new item will
appear under Ports (COM & LPT). You'll find a different (COM#) after this item in the
list.
Sometimes the item will refer to the name of the board. Other times it may be called
something like USB Serial Device, as seen in the image above. Either way, there is a
new (COM#) following the name. This is the port your board is using.
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Install Putty
If you're using Windows, you'll need to download a terminal program. You're going to
use PuTTY.
The first thing to do is download the latest version of PuTTY(https://adafru.it/Bf1).
You'll want to download the Windows installer file. It is most likely that you'll need the
64-bit version. Download the file and install the program on your machine. If you run
into issues, you can try downloading the 32-bit version instead. However, the 64-bit
version will work on most PCs.
Now you need to open PuTTY.
Under Connection type: choose the button next to Serial.
•
In the box under Serial line, enter the serial port you found that your board is
•
using.
In the box under Speed, enter 115200. This called the baud rate, which is the
•
speed in bits per second that data is sent over the serial connection. For boards
with built in USB it doesn't matter so much but for ESP8266 and other board
with a separate chip, the speed required by the board is 115200 bits per second.
So you might as well just use 115200!
If you want to save those settings for later, use the options under Load, save or delete
a stored session. Enter a name in the box under Saved Sessions, and click the Save
button on the right.
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Once your settings are entered, you're ready to connect to the serial console. Click
"Open" at the bottom of the window. A new window will open.
If no code is running, the window will either be blank or will look like the window
above. Now you're ready to see the results of your code.
Great job! You've connected to the serial console!
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Advanced Serial Console on Mac
Connecting to the serial console on Mac does not require installing any drivers or
extra software. You'll use a terminal program to find your board, and screen to
connect to it. Terminal and screen both come installed by default.
What's the Port?
First you'll want to find out which serial port your board is using. When you plug your
board in to USB on your computer, it connects to a serial port. The port is like a door
through which your board can communicate with your computer using USB.
The easiest way to determine which port the board is using is to first check without
the board plugged in. Open Terminal and type the following:
ls /dev/tty.*
Each serial connection shows up in the /dev/ directory. It has a name that starts with
tty. . The command ls shows you a list of items in a directory. You can use * as a
wildcard, to search for files that start with the same letters but end in something
different. In this case, you're asking to see all of the listings in /dev/ that start with t
ty. and end in anything. This will show us the current serial connections.
Now, plug your board. In Terminal, type:
ls /dev/tty.*
This will show you the current serial connections, which will now include your board.
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A new listing has appeared called /dev/tty.usbmodem141441 . The tty.usbmodem
141441 part of this listing is the name the example board is using. Yours will be called
something similar.
Using Linux, a new listing has appeared called /dev/ttyACM0 . The ttyACM0 part of
this listing is the name the example board is using. Yours will be called something
similar.
Connect with screen
Now that you know the name your board is using, you're ready connect to the serial
console. You're going to use a command called screen . The screen command is
included with MacOS. To connect to the serial console, use Terminal. Type the
following command, replacing board_name with the name you found your board is
using:
screen /dev/tty.board_name 115200
The first part of this establishes using the screen command. The second part tells
screen the name of the board you're trying to use. The third part tells screen what
baud rate to use for the serial connection. The baud rate is the speed in bits per
second that data is sent over the serial connection. In this case, the speed required
by the board is 115200 bits per second.
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Press enter to run the command. It will open in the same window. If no code is
running, the window will be blank. Otherwise, you'll see the output of your code.
Great job! You've connected to the serial console!
"Uninstalling" CircuitPython
A lot of our boards can be used with multiple programming languages. For example,
the Circuit Playground Express can be used with MakeCode, Code.org CS
Discoveries, CircuitPython and Arduino.
Maybe you tried CircuitPython and want to go back to MakeCode or Arduino? Not a
problem. You can always remove or reinstall CircuitPython whenever you want! Heck,
you can change your mind every day!
There is nothing to uninstall. CircuitPython is "just another program" that is loaded
onto your board. You simply load another program (Arduino or MakeCode) and it will
overwrite CircuitPython.
Backup Your Code
Before replacing CircuitPython, don't forget to make a backup of the code you have
on the CIRCUITPY drive. That means your code.py any other files, the lib folder etc.
You may lose these files when you remove CircuitPython, so backups are key! Just
drag the files to a folder on your laptop or desktop computer like you would with any
USB drive.
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Moving Circuit Playground Express to MakeCode
On the Circuit Playground Express (this currently does NOT apply to Circuit
Playground Bluefruit), if you want to go back to using MakeCode, it's really easy. Visit
makecode.adafruit.com(https://adafru.it/wpC) and find the program you want to
upload. Click Download to download the .uf2 file that is generated by MakeCode.
Now double-click your CircuitPython board until you see the onboard LED(s) turn
green and the ...BOOT directory shows up.
Then find the downloaded MakeCode .uf2 file and drag it to the CPLAYBOOT drive.
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Your MakeCode is now running and CircuitPython has been removed. Going forward
you only have to single click the reset button to get to CPLAYBOOT. This is an
idiosyncrasy of MakeCode.
Moving to Arduino
If you want to use Arduino instead, you just use the Arduino IDE to load an Arduino
program. Here's an example of uploading a simple "Blink" Arduino program, but you
don't have to use this particular program.
Start by plugging in your board, and double-clicking reset until you get the green
onboard LED(s).
Within Arduino IDE, select the matching board, say Circuit Playground Express.
Select the correct matching Port:
Create a new simple Blink sketch example:
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
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}
// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
Make sure the LED(s) are still green, then click Upload to upload Blink. Once it has
uploaded successfully, the serial Port will change so re-select the new Port!
Once Blink is uploaded you should no longer need to double-click to enter
bootloader mode. Arduino will automatically reset when you upload.
Troubleshooting
From time to time, you will run into issues when working with CircuitPython. Here are
a few things you may encounter and how to resolve them.
As CircuitPython development continues and there are new releases, Adafruit
will stop supporting older releases. Visit https://circuitpython.org/downloads 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 https://circuitpython.org/libraries to
download the latest Library Bundle.
Always Run the Latest Version of CircuitPython and Libraries
As CircuitPython development continues and there are new releases, Adafruit will
stop supporting older releases. You need to update to the latest CircuitPython.(https:
//adafru.it/Em8).
You need to download the CircuitPython Library Bundle that matches your version of
CircuitPython. Please update CircuitPython and then download the latest bundle(http
s://adafru.it/ENC).
As new versions of CircuitPython are released, Adafruit will stop providing the
previous bundles as automatically created downloads on the Adafruit CircuitPython
Library Bundle repo. If you must continue to use an earlier version, you can still
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download the appropriate version of mpy-cross from the particular release of
CircuitPython on the CircuitPython repo and create your own compatible .mpy library
files. However, it is best to update to the latest for both CircuitPython and the library
bundle.
I have to continue using CircuitPython 5.x or earlier. Where can I find compatible libraries?
Adafruit is no longer building or supporting the CircuitPython 5.x or earlier library
bundles. You are highly encourged to update CircuitPython to the latest version(http
s://adafru.it/Em8) and use the current version of the libraries(https://adafru.it/ENC).
However, if for some reason you cannot update, links to the previous bundles are
available in the FAQ(https://adafru.it/FwY).
Bootloader (boardnameBOOT) Drive Not Present
You may have a different board.
Only Adafruit Express boards and the SAMD21 non-Express boards ship with the UF2
bootloader (https://adafru.it/zbX)installed. The Feather M0 Basic, Feather M0
Adalogger, and similar boards use a regular Arduino-compatible bootloader, which
does not show a boardnameBOOT drive.
MakeCode
If you are running a MakeCode(https://adafru.it/zbY) program on Circuit Playground
Express, press the reset button just onceto get the CPLAYBOOT drive to show up.
Pressing it twice will not work.
MacOS
DriveDx and its accompanything SAT SMART Driver can interfere with seeing the
BOOT drive. See this forum post(https://adafru.it/sTc) for how to fix the problem.
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Windows 10
Did you install the Adafruit Windows Drivers package by mistake, or did you upgrade
to Windows 10 with the driver package installed? You don't need to install this
package on Windows 10 for most Adafruit boards. The old version (v1.5) can interfere
with recognizing your device. Go to Settings -> Apps and uninstall all the "Adafruit"
driver programs.
Windows 7 or 8.1
To use a CircuitPython-compatible board with Windows 7 or 8.1, you must install a
driver. Installation instructions are available here(https://adafru.it/VuB).
It is recommended(https://adafru.it/Amd) that you upgrade to Windows 10 if possible;
an upgrade is probably still free for you. Check here(https://adafru.it/Amd).
The Windows Drivers installer was last updated in November 2020 (v2.5.0.0) .
Windows 7 drivers for CircuitPython boards released since then, including
RP2040 boards, are not yet available. The boards work fine on Windows 10. A
new release of the drivers is in process.
You should now be done! Test by unplugging and replugging the board. You should
see the CIRCUITPY drive, and when you double-click the reset button (single click on
Circuit Playground Express running MakeCode), you should see the appropriateboar
dnameBOOT drive.
Let us know in the Adafruit support forums(https://adafru.it/jIf) or on the Adafruit
Discord() if this does not work for you!
Windows Explorer Locks Up When Accessing boardnameBOOT Drive
On Windows, several third-party programs that can cause issues. The symptom is that
you try to access the boardnameBOOTdrive, and Windows or Windows Explorer
seems to lock up. These programs are known to cause trouble:
AIDA64: to fix, stop the program. This problem has been reported to AIDA64.
•
They acquired hardware to test, and released a beta version that fixes the
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problem. This may have been incorporated into the latest release. Please let us
know in the forums if you test this.
Hard Disk Sentinel
•
Kaspersky anti-virus: To fix, you may need to disable Kaspersky completely.
•
Disabling some aspects of Kaspersky does not always solve the problem. This
problem has been reported to Kaspersky.
ESET NOD32 anti-virus: There have been problems with at least version
•
9.0.386.0, solved by uninstallation.
Copying UF2 to boardnameBOOT Drive Hangs at 0% Copied
On Windows, a Western DIgital (WD) utility that comes with their external USB drives
can interfere with copying UF2 files to the boardnameBOOT drive. Uninstall that utility
to fix the problem.
CIRCUITPY Drive Does Not Appear
Kaspersky anti-virus can block the appearance of the CIRCUITPY drive. There has not
yet been settings change discovered that prevents this. Complete uninstallation of
Kaspersky fixes the problem.
Norton anti-virus can interfere with CIRCUITPY. A user has reported this problem on
Windows 7. The user turned off both Smart Firewall and Auto Protect, and CIRCUITPY
then appeared.
Device Errors or Problems on Windows
Windows can become confused about USB device installations. This is particularly
true of Windows 7 and 8.1. It is recommended(https://adafru.it/Amd) that you upgrade
to Windows 10 if possible; an upgrade is probably still free for you: see this link(https
://adafru.it/V2a).
If not, try cleaning up your USB devices. Use Uwe Sieber's Device Cleanup Tool(http
s://adafru.it/RWd). Download and unzip the tool. Unplug all the boards and other USB
devices you want to clean up. Run the tool as Administrator. You will see a listing like
this, probably with many more devices. It is listing all the USB devices that are not
currently attached.
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Select all the devices you want to remove, and then press Delete. It is usually safe
just to select everything. Any device that is removed will get a fresh install when you
plug it in. Using the Device Cleanup Tool also discards all the COM port assignments
for the unplugged boards. If you have used many Arduino and CircuitPython boards,
you have probably seen higher and higher COM port numbers used, seemingly
without end. This will fix that problem.
Serial Console in Mu Not Displaying Anything
There are times when the serial console will accurately not display anything, such as,
when no code is currently running, or when code with no serial output is already
running before you open the console. However, if you find yourself in a situation
where you feel it should be displaying something like an error, consider the following.
Depending on the size of your screen or Mu window, when you open the serial
console, the serial console panel may be very small. This can be a problem. A basic
CircuitPython error takes 10 lines to display!
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
Traceback (most recent call last):
File "code.py", line 7
SyntaxError: invalid syntax
Press any key to enter the REPL. Use CTRL-D to reload.
More complex errors take even more lines!
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Therefore, if your serial console panel is five lines tall or less, you may only see blank
lines or blank lines followed by Press any key to enter the REPL. Use CTRL-D
to reload. . If this is the case, you need to either mouse over the top of the panel to
utilise the option to resize the serial panel, or use the scrollbar on the right side to
scroll up and find your message.
This applies to any kind of serial output whether it be error messages or print
statements. So before you start trying to debug your problem on the hardware side,
be sure to check that you haven't simply missed the serial messages due to serial
output panel height.
code.py Restarts Constantly
CircuitPython will restart code.py if you or your computer writes to something on the
CIRCUITPY drive. This feature is called auto-reload, and lets you test a change to your
program immediately.
Some utility programs, such as backup, anti-virus, or disk-checking apps, will write to
the CIRCUITPY as part of their operation. Sometimes they do this very frequently,
causing constant restarts.
Acronis True Image and related Acronis programs on Windows are known to cause
this problem. It is possible to prevent this by disabling the "(https://adafru.it/XDZ)Acr
onis Managed Machine Service Mini"(https://adafru.it/XDZ).
If you cannot stop whatever is causing the writes, you can disable auto-reload by
putting this code in boot.py or code.py:
import supervisor
supervisor.disable_autoreload()
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CircuitPython RGB Status Light
Nearly all CircuitPython-capable boards have a single NeoPixel or DotStar RGB LED
on the board that indicates the status of CircuitPython. A few boards designed before
CircuitPython existed, such as the Feather M0 Basic, do not.
Circuit Playground Express and Circuit Playground Bluefruit have multiple RGB LEDs,
but do NOT have a status LED. The LEDs are all green when in the bootloader. In
versions before 7.0.0, they do NOT indicate any status while running CircuitPython.
CircuitPython 7.0.0 and Later
The status LED blinks were changed in CircuitPython 7.0.0 in order to save battery
power and simplify the blinks. These blink patterns will occur on single color LEDs
when the board does not have any RGB LEDs. Speed and blink count also vary for
this reason.
On start up, the LED will blink YELLOW multiple times for 1 second. Pressing reset
during this time will restart the board and then enter safe mode. On Bluetooth
capable boards, after the yellow blinks, there will be a set of faster blue blinks.
Pressing reset during the BLUE blinks will clear Bluetooth information and start the
device in discoverable mode, so it can be used with a BLE code editor.
Once started, CircuitPython will blink a pattern every 5 seconds when no user code is
running to indicate why the code stopped:
1 GREEN blink: Code finished without error.
•
2 RED blinks:Code ended due to an exception. Check the serial console for
•
details.
3 YELLOW blinks:CircuitPython is in safe mode. No user code was run. Check
•
the serial console for safe mode reason.
When in the REPL, CircuitPython will set the status LED to WHITE. You can change the
LED color from the REPL. The status indicator will not persist on non-NeoPixel or
DotStar LEDs.
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CircuitPython 6.3.0 and earlier
Here's what the colors and blinking mean:
steady GREEN: code.py (or code.txt, main.py, or main.txt) is running
•
pulsing GREEN: code.py (etc.) has finished or does not exist
•
steady YELLOW at start up: (4.0.0-alpha.5 and newer) CircuitPython is waiting for
•
a reset to indicate that it should start in safe mode
pulsing YELLOW: Circuit Python is in safe mode: it crashed and restarted
•
steady WHITE: REPL is running
•
steady BLUE: boot.py is running
•
Colors with multiple flashes following indicate a Pythonexception and then indicate
the line number of the error. The color of the first flash indicates the type of error:
GREEN:IndentationError
•
CYAN:SyntaxError
•
WHITE: NameError
•
ORANGE: OSError
•
PURPLE: ValueError
•
YELLOW: other error
•
These are followed by flashes indicating the line number, including place value. WHIT
E flashes are thousands' place, BLUE are hundreds' place, YELLOW are tens' place,
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and CYAN are one's place. So for example, an error on line 32 would flash YELLOW
three times and then CYAN two times. Zeroes are indicated by an extra-long dark gap.
Serial console showing ValueError:
Incompatible .mpy file
This error occurs when importing a module that is stored as a .mpy binary file that
was generated by a different version of CircuitPython than the one its being loaded
into. In particular, the mpy binary format changed between CircuitPython versions 6.x
and 7.x, 2.x and 3.x, and 1.x and 2.x.
So, for instance, if you upgraded to CircuitPython 7.x from 6.x you’ll need to download
a newer version of the library that triggered the error on import . All libraries are
available in the Adafruit bundle(https://adafru.it/y8E).
CIRCUITPY Drive Issues
You may find that you can no longer save files to your CIRCUITPY drive. You may find
that your CIRCUITPY stops showing up in your file explorer, or shows up as NO_NAM
E. These are indicators that your filesystem has issues. When the CIRCUITPY disk is
not safely ejected before being reset by the button or being disconnected from USB,
it may corrupt the flash drive. It can happen on Windows, Mac or Linux, though it is
more common on Windows.
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