Adafruit METRO M0 Express - designed for CircuitPython - ATSAMD21G18

by Adafruit

Metro is Adafruits series of microcontroller boards for use with the Arduino IDE. This new Metro M0 Express board looks a whole lot like their 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 Metro that is designed for use with CircuitPython!

CircuitPython is Adafruits beginner-oriented flavor of MicroPython - and as the name hints at, its a small but full-featured version of the popular Python programming language specifically for use with circuitry and electronics.

Not only can you use CircuitPython, but the Metro M0 is also usable in the Arduino IDE.

At the Metro M0's heart is an ATSAMD21G18 ARM Cortex M0 processor, clocked at 48 MHz and at 3.3V logic, the same one used in the new Arduino Zero. This chip has a whopping 256K of FLASH (8x more than the Atmega328) and 32K 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.

  • Power the METRO with 7-9V polarity protected DC or the micro USB connector to any 5V USB source. The 2.1mm 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 3.3V
  • 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. When used in Arduino, you can read/write files to it, like a little datalogger or SD card, and then with the helper program, access the files over USB.
  • 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. Also included are 4 rubber bumpers to keep it from slipping off your desk. No soldering required to use, plug and play!

Check out the full guide for pinouts, schematics, drivers, instructions, Fritzing object, and more!

Please note, CircuitPython is still in beta and Adafruit are working hard to make it awesome! So please pick up an M0 Express if you want to try it out - maybe even help them find bugs and make improvements! You can of course use the Metro M0 in Arduino IDE as much as you like, which is well supported.

TECHNICAL DETAILS

Detailed specifications:

  • ATSAMD21G18 @ 48MHz with 3.3V logic/power
  • 256KB of FLASH + 32KB of RAM
  • 2 MB SPI Flash chip
  • No EEPROM
  • 32.768 KHz crystal for clock generation & RTC
  • 3.3V regulator with 500mA peak current output
  • USB native support, comes with USB bootloader and serial port debugging
  • You also get tons of pins - 25 GPIO pins, 5 more than the Metro 328
  • Hardware Serial, hardware I2C, hardware SPI support
  • PWM outputs on almost all pins
  • 6 x 12-bit analog inputs
  • 1 x 10-bit analog output (DAC)
  • Built in NeoPixel on pin #40
  • Pin #13 red LED for general purpose blinking
  • Power on/off switch
  • 4 mounting holes
  • 4 rubber bumpers to keep it from slipping off your desk
  • Reset button
  • Adafruit Black PCB with gold plate on pads
  • Dimensions: 71mm x 53mm / 2.8" x 2.1"
  • Height (w/ barrel jack): 13mm / 0.5"
  • Weight: 20g

41 customer reviews

a year ago
Brilliant for use with a pi1541 and epyx fast load cart for a c64, as the pi zero needs overclocking in order to work. This keeps temps down and is rock solid stable. Brilliant!
by Rian about Raspberry Pi Zero Heatsink via REVIEWS.io
2 years ago
Fits perfectly flush in the coupe case and gives plenty of clearance for the hat on top. Shaves off a little bit of heat overhead for long running applications.
by Anonymous about Raspberry Pi Zero Heatsink via REVIEWS.io
3 years ago
Simple enough to fit. All rather subjective but the pi3 case (running Flightaware 24/7) does 'feel' a little cooler.
by Hagley about Raspberry Pi Zero Heatsink via REVIEWS.io
3 years ago
Works as intended, when used on a Pi Zero 2 W with Display Mini Hat, I used extended headers on the Pi and then added the Display, keeping the heatsink clear of the Display above.
by Sagar about Raspberry Pi Zero Heatsink via REVIEWS.io
3 years ago
Perfect fit, looks smart. Can't attest to it's thermal performance (forgot to check) but it's better than nowt!
by Anonymous about Raspberry Pi Zero Heatsink via REVIEWS.io
4 years ago
It works really well. We have had a heatwave in Malta and my Pi is in the hottest room in the house and worked perfectly keeping well below the temperature
by Christian about Raspberry Pi Zero Heatsink via REVIEWS.io
4 years ago
Simple but easy to fix and does a good job of dissipating some of the Pi 4B's heat output from the secondary on-board chips [tested on Pi 4B].
by Anonymous about Raspberry Pi Zero Heatsink via REVIEWS.io
4 years ago
Only a small piece of metal with a bit of sticky tape, but it does the job! My RPi kept throttling due to overheating once I installed the hat. This smooths out the overheating and reduced how often and quickly the pie throttles. I might still have to improve the airflow for my purpose, but this has taken off the edge already.
by Stephan about Raspberry Pi Zero Heatsink via REVIEWS.io
4 years ago
Just what I needed. Along with Pimoroni's premium standoffs provides the perfect solution for both hifiberry and iqaudio DACs. I have no doubt that they will perfect for any Pi + HAT build.
by Steve about Raspberry Pi Zero Heatsink via REVIEWS.io
4 years ago
communication was superb, texted delivery time to my phone and the order was complete. the package was boxed really well and invoice was checked over. I am hoping to make more purchases in the very near future.
by Paul about Raspberry Pi Zero Heatsink via REVIEWS.io
5 years ago
Great little heatsink. Easy to fit and keeps my Raspberry Pi 3b cool while it runs pi.hole and pivpn software for me 24/7. I can also confirm that this fits under the official power-over-ethernet hat, sitting just under the fan to increase the effect of active cooling.
by Harley about Raspberry Pi Zero Heatsink via REVIEWS.io
6 years ago
This is a tiny heatsink which attaches to the processor of your Raspberry Pi (I've used this on a Pi Zero and a "proper" Pi) with a self-adhesive patch. Simply remove the protective paper, press it onto the top of the processor, and you're done. Helps keep the Pi cooler while it is running, and for a price like this you can't go wrong.
by Peter about Raspberry Pi Zero Heatsink via REVIEWS.io
6 years ago
Simple Headsink with Glue on the base. Easy to install, full in Function - it cools down the Processor. If you have the Pi idle nearly all the time the heatsink is not necessary, but if you have intensive processes to run it's gold.
by Mario about Raspberry Pi Zero Heatsink via REVIEWS.io
6 years ago
Exactly as expected and there isn't really a lot to say about it. Quality seems to be good, and it takes three seconds to mount it.
by Steffen about Raspberry Pi Zero Heatsink via REVIEWS.io
6 years ago
Does exactly what you expect. Does it well. Be sure to consider whether there is room for pHATs, HATs, or other items which might be above. I haven't done specific checks to determine exactly how effective. Subjectively, however, I have seen improvements from before and after.
by Anonymous about Raspberry Pi Zero Heatsink via REVIEWS.io
6 years ago
This is now my "go-to" size for heatsink. You can get taller ones, but they eventually end up getting in the way. Would be even better if they were stocked in different colours as well though.
by Matt about Raspberry Pi Zero Heatsink via REVIEWS.io
7 years ago
Tiny heatsinks with pre applied sticky tape on the bottom side, ready for use straight away (just peel away the protective layer). Fits the Raspberry Pi perfectly but is also a good choice for lots of other computer related stuff. Their size and shape makes them quite modular and easy to use for lots of old retro computers as well.
by Magnus about Raspberry Pi Zero Heatsink via REVIEWS.io
7 years ago
I bought the 6mm version of the heatsink, which in combination with the Pibow Coupé case, still allows me to use various HATs with my Raspberry Pi 3B+. It comes with adhesive - simply peel off the tape, and apply the heatsink to the processor. Very simple and straightforward to install.
by Matt about Raspberry Pi Zero Heatsink via REVIEWS.io
7 years ago
A great addiction for the Raspberry PI ! I'm going to use the Raspberry PI to manage my Ubiquity network and I'm going to have it always on in a Pibow Coupé ! With a heatsink, I can keep the Raspberry PI cool without losing the style it gets with the Pibow Coupé !
by Bruno about Raspberry Pi Zero Heatsink via REVIEWS.io
7 years ago
Part of number of items bought for a night vision camera with Raspberry Pi Zero W and was quickly delivered, This is my first Raspberry Pi project but it easy to assemble and it works well.
by Anonymous about Raspberry Pi Zero Heatsink via REVIEWS.io
8 years ago
I'm using the heatsink with a Pi3 inside a pibow coupe. The pibow is placed horizontally. The heatsink fits nicely inside the pibow window and I attached it to the Pi3 after I placed it inside the pibow. Great item.
by alex01gt about Raspberry Pi Zero Heatsink via REVIEWS.io
8 years ago
I've only been using my heatsink a few days but in that time my Pi hasn't been turned off and I haven't noticed any heating issues so thats a great purchase in my book
by Liam about Raspberry Pi Zero Heatsink via REVIEWS.io
8 years ago
Does the job very well, first thing i notice on my raspberry is that warms up quickly, bought a 6mm one, now is cooler than ever, is a must have.
by Julian about Raspberry Pi Zero Heatsink via REVIEWS.io
9 years ago
Was so nice install it, was so simple, i thought i need some glue or thermal paste but not was necessary, 1. just unpackaged, 2. remove the paper, 3 paste into the raspberry pi processor. DONE, NOW SO COOL THERE.
by Franz about Raspberry Pi Zero Heatsink via REVIEWS.io
9 years ago
These tiny heatsinks are super value. I bought 2 of them one each for a pi2 and a pi3. There is a noticeable difference in the reduction of CPU temperature, especially on the media serving pi2.
by Darren about Raspberry Pi Zero Heatsink via REVIEWS.io
9 years ago
Get a 6mm one, as the 7.5mm, which was available at the time I bought it, it may interfere with HAT boards as described here. Maybe you won't use it at first, but it is future proof.
by David about Raspberry Pi Zero Heatsink via REVIEWS.io
9 years ago
very easy to apply to your pi, and for a pound it is super cheap and well supported with the pi bow case, also looks awesome for a heat sink, I'm impressed, and might buy more for my other many pis
by Sylvain about Raspberry Pi Zero Heatsink via REVIEWS.io

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