Metro M0 Express
by Adafruit
This Metro M0 Express board looks a whole lot like the original Metro 328, but with a huge upgrade. Instead of the ATmega328, this Metro features a ATSAMD21G18 chip, an ARM Cortex M0+. It’s the first Adafruit Metro that is designed for use with CircuitPython!
At the Metro M0’s heart is an ATSAMD21G18 ARM Cortex M0 processor, clocked at 48 MHz and at 3.3 V logic, the same one used in the new Arduino Zero. This chip has a whopping 256 KB of FLASH (8x more than the Atmega328) and 32 KB of RAM (16x as much)! This chip comes with built in USB so it has USB-to-Serial program & debug capability built in with no need for an FTDI-like chip.
Technical details
- Power the METRO with 7-9 V polarity protected DC or the micro USB connector to any 5 V USB source. The 2.1 mm DC jack has an on/off switch next to it so you can turn off your setup easily. The METRO will automagically switch between USB and DC.
- METRO has 25 GPIO pins, 12 of which are analog in, and one of which is a true analog out. There’s a hardware SPI port, hardware I2C port and hardware UART. Logic level is 3.3 V.
- Native USB, there’s no need for a hardware USB to Serial converter as the Metro M0 has built in USB support. When used to act like a serial device, the USB interface can be used by any computer to listen/send data to the METRO, and can also be used to launch and update code via the bootloader. It can also act like a keyboard, mouse or MIDI device as well.
- Four indicator LEDs and one NeoPixel, on the front edge of the PCB, for easy debugging. One green power LED, two RX/TX LEDs for data being sent over USB, and a red LED connected. Next to the reset button there is an RGB NeoPixel that can be used for any purpose.
- 2 MB SPI Flash storage chip is included on board. You can use the SPI Flash storage like a very tiny hard drive. When used in Circuit Python, the 2 MB flash acts as storage for all your scripts, libraries and files.
- Easy reprogramming, comes pre-loaded with the UF2 bootloader, which looks 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, PXT/MakeCode or Arduino IDE (it is bossa-compatible).
Comes fully assembled with headers, tested, and with the UF2 bootloader loaded on. Includes 4 rubber bumpers to keep it from slipping off your desk. No soldering required to use, plug and play!
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CircuitPython 9.0.4
This is the latest stable release of CircuitPython that will work with the Metro M0 Express.
Use this release if you are new to CircuitPython.
Built-in modules available: adafruit_pixelbuf, analogio, array, audiobusio, audiocore, audioio, board, builtins, busdisplay, busio, busio.SPI, busio.UART, codeop, collections, digitalio, displayio, epaperdisplay, errno, fontio, fourwire, i2cdisplaybus, locale, math, microcontroller, neopixel_write, nvm, onewireio, os, paralleldisplaybus, pulseio, pwmio, rainbowio, random, rotaryio, rtc, storage, struct, supervisor, sys, terminalio, time, touchio, usb_cdc, usb_hid, usb_midi, warnings
CircuitPython 9.1.0-beta.1
This is the latest development release of CircuitPython that will work with the Metro M0 Express.
Alpha development releases are early releases. They are unfinished, are likely to have bugs, and the features they provide may change. Beta releases may have some bugs and unfinished features, but should be suitable for many uses. A Release Candidate (rc) release is considered done and will become the next stable release, assuming no further issues are found.
Please try alpha, beta, and rc releases if you are able. Your testing is invaluable: it helps us uncover and find issues quickly.
Release Notes for 9.1.0-beta.1
Built-in modules available: adafruit_pixelbuf, analogio, array, audiobusio, audiocore, audioio, board, builtins, busdisplay, busio, busio.SPI, busio.UART, codeop, collections, digitalio, displayio, epaperdisplay, errno, fontio, fourwire, i2cdisplaybus, locale, math, microcontroller, neopixel_write, nvm, onewireio, os, paralleldisplaybus, pulseio, pwmio, rainbowio, random, rotaryio, rtc, storage, struct, supervisor, sys, terminalio, time, touchio, usb_cdc, usb_hid, usb_midi, warnings
Absolute Newest
Every time we commit new code to CircuitPython we automatically build binaries for each board and language. The binaries are stored on Amazon S3, organized by board, and then by language. These releases are even newer than the development release listed above. Try them if you want the absolute latest and are feeling daring or want to see if a problem has been fixed.
Previous Versions of CircuitPython
All previous releases of CircuitPython are available for download from Amazon S3 through the button below. For very old releases, look in the OLD/ folder for each board. Release notes for each release are available at GitHub button below.
Older releases are useful for testing if you something appears to be broken in a newer release but used to work, or if you have older code that depends on features only available in an older release. Otherwise we recommend using the latest stable release.
Update UF2 Bootloader
Latest version: v3.15.0
The bootloader allows you to load CircuitPython, MakeCode, and Arduino programs. The bootloader is not CircuitPython. You can check the current version of your bootloader by looking in the INFO_UF2.TXT file when the BOOT drive is visible (FEATHERBOOT, CPLAYBOOT, etc.).
It is not necessary to update your bootloader if it is working fine. Read the release notes on GitHub to see what has been changed. In general, we recommend you not update the bootloader unless you know there is a problem with it or a support person has asked you to try updating it.
To update, first save the contents of CIRCUITPY, just in case. Then double-click the reset button to show the BOOT drive. Drag the update-bootloader .uf2 file to the BOOT drive. Wait a few tens of seconds for the bootloader to update; the BOOT drive will reappear. After you update, check INFO_UF2.TXT to verify that the bootloader version has been updated. Then you will need to reload CircuitPython.