User Manual

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.

CircuitPython RGB Status Light

The Feather M0 Express, Feather M4 Express, Metro M0 Express, Metro M4 Express, ItsyBitsy M0 Express, ItsyBitsy M4

Express, Gemma M0, and Trinket M0 all have a single NeoPixel or DotStar RGB LED on the board that indicates the

status of CircuitPython.

Circuit Playground Express does NOT have a status LED. The LEDs will pulse green when in the bootloader. They do

NOT indicate any status while running CircuitPython.

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 Python exception 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. WHITE flashes are thousands' place,

BLUE are hundreds' place, YELLOW are tens' place, 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.

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 2.x and 3.x, as well as between 1.x and 2.x.

So, for instance, if you upgraded to CircuitPython 3.x from 2.x you’ll need to download a newer version of the library

that triggered the error on import . They are all available in the Adafruit bundle (https://adafru.it/y8E).