Seeeduino XIAO The Smallest Arduino Microcontroller Based on SAMD21,with Rich Interfaces, 100% Arduino IDE Compatible, desiged for Projects Need Arduino Micro，3 pcs

This purchase was for a box of 3 of the Seeeduino XIAO Arduino compatible controllers based on SAMD21 microcontroller. I am having issues with them being unreliable in establishing a USB connection when using the Arduino IDE to upload a sketch to them. Even using the basic “blink” example sketch, it will work 2 or three times and then will stop working. Powering the computer down and restarting from a powered off point I can get them to work again for 2-3 iterations (without changing the sketch). I use many different Arduino type products and have no issues with the connection to those. From looking at other reviews, many people seem pleased and are having no problems but looking at the related forums, similar issues are common with other users. Just a heads up. The product idea and the size/format is great! I wouldn’t plan on using this in a product based on the Arduino boot loader however until they are proven out.Update.... The issues I was seeing with these units is somehow related to the USB HUB I have been using. When I eliminate the HUB, these modules will download every time. I still find this "interesting" because all of the other Arduino based boards I use work fine with the HUB. I have designed a few boards that use the Arduino ATmega328P and the bootloader that all work fine with the HUB. Anyway.... take it for what it's worth.

I used this microcontroller for making a DIY Stream Deck the complete project costed me about $15 per Stream Deck with cherry brown switches. You can find my cad files and code at thingiverse thing:4602619.- The product arrived on time- It is compatible with Arduino Library- It is compatible with ARM Cortex-M0+ Assembly- despite its size it is still very easy to solder- It uses a USB type C which makes it perfect for HID projects- The processor is fast, supports onboard serial and thanks to Arduino library compatible with all of your Arduino and Teensyduino code.I do not recommend this for people with poor soldering skills or people who are not familiar with microcontrollers and want to get into this field. For that I recommend an Arduino Uno or Uno compatible clones.

I can't comment on alot of the specific ins and outs of the product because I've yet to run anything other than a blink test sketch to confirm that they work with Arduino and are functional, all 3 were!Like I mentioned in the title, this product has alot going for it:Price: $21.99 for 3 of them so..roughly(rounded up from $7.3) $8 per controller! That's $1-$2 less than Adafruit's Trinket M0 which features the same hardware but does include an RGB LED. I'll take price-to-performance value over a stupid RGB light any day!Size: They are tiny! Perfect for permanent installation onto a breadboard/protoboard or even a PCB(They have castellated edges so you could indeed SMT solder these with the proper technique and good paste/equipment)Specifications: Very good for something so small. SAMD21(Cortex M0) @ 48MHz w/ 256K of Flash!** I will say that I would've liked to see(and would've paid an extra dollar or two) an external Flash chip, maybe a 1MB or 2MB size? Adafruit does this in their larger boards and premium products in order to accomodate CircuitPython, they don't have external/extra flash on the Trinket M0(Which this is comparable too), so maybe its simply a size thing. ALTHOUGH, I think they could've easily fit a 1-2MB SOIC Type flash chip on the bottom of the pcb.Overall, a great buy for anyone on a budget or with limited funds thats looking for some bang out of their buck!

Fired up all three that came in the three-pack and they are fine. Spent considerable time trying to get them working on Linux (Mint) using the Arduino IDE with (nearly) no success. Tried to flash them about a dozen times and only got it to work once. I suspect there is something messed up with the USB drivers. The only reference on the Seeed website to using Linux and the Arduino IDE for the Xiao is a post on their blog that simply says “Run arduino-linux-setup.sh”. I did that and it did seem to improve the USB responses in syslog when I plugged the board in. Still only got it to work once.Set it up in Windows and it worked perfectly fine, every time. Next ill try Arduino CLI but given my experience with the GUI IDE, I don’t think the CLI version is going to work either.I haven’t logged a lot of hours working with these yet but they appear to be a good choice if you need something REALLY small and only need to make a few external connections. You should also know that the memory is limited on these. The vaunted “blinky” sketch that we’ve all run a million times occupies 13% of available memory. Again, this shouldn’t be a problem as you aren’t going to be controlling eight motors and connecting to 12 sensors with one of these.

This beautiful tiny microcontroller is absolutely perfect for anyone trying to level up their arduino projects. The only pain is you need to buy a pack a cheap pack of level shifters (I recommend a 10pk of 4-channel two-way shifters) to convert any 5v signals to the 3v the XIAO needs.The XIAO is beautiful, tiny, fast, and has so so much more memory for long programs compared to the arduino uno or nano.The blazing fast clock speed makes controlling stepper motors that much better.Absolutely loving these, buy a 3-pack because you'll find so many more uses.USB-C is another bonus.Soldering on the pins is a breeze. (if you want to use them- another advantage is soldering straight to wires for small applications)Have fun!