XIAO SAMD21

I bought 3 of these a couple years ago to play around with. At the time, it was just because they were cheap and quick to get on Amazon. I quickly fell in love. Though they aren't perfect. Pros: Size. They're tiny. Even 2 years on, most microcontrollers are *at least* 2 to 4 times the size. The small size makes them easy to fit into almost any project. They're literally the size of a postage stamp. I can cover one with my finger. Which brings me to the next pro: I/O. Even at this tiny size, you still have tons of I/O, with support for hardware interrupts, UART, I2C, SPI, and true analog pins with DAC. The big one for me, though, is HID support through the USB type C port. That's a much less common feature than you'd think. If you want to make devices that can talk to other devices as an input device, you need this. Speed. You don't really think that a simple Arduino device needs to be fast, but having a 48mhz processor and 32mb of SRAM to work with open up a LOT of possibilities. Take, for example, my most recent project. I wanted to make a vintage laptop keyboard work with a modern laptop motherboard. But I wanted to do so without damaging the original keyboard. So to interface the two, I needed the Xiao to be able to read the PS/2 protocol that the keyboard was talking in, and give USB HID protocol commands to the computer. Reading the PS/2 protocol takes very precise timing. Your code has to execute within a certain number of microseconds, otherwise the command will fail. Because of the speed of the processor, I could have more code executing in the interrupts while still staying under the threshold. Cons: Storage. While I've never run up against the limit, the Xiao has 256 kB of flash memory. That's not the smallest, but it's certainly not the biggest I've seen on a microcontroller. So I do get a little nervous when I start importing a bunch of libraries. So far, my most involved project, the keyboard that I talked about earlier, only uses about 25% of that storage. And that's importing two different libraries plus my custom code. But if you have a large project that takes many libraries or a whole lot of code, you might run into problems with storage. Bootloader Corruption. I've only had it happen once and it was after hundreds upon hundreds of code uploads. These guys saying they're bricking after 50 uploads have to be doing something wrong. Or maybe it's because they're on Mac hardware, I don't know. But I've had to upload 50 times pretty much everyday I've worked on this project and so far it's not been a problem. But like I said, I did have one of my original three stop responding to USB. So the problem does exist. The device itself still does what the last upload of code told it to do, but I can no longer get it to talk with the Arduino software. And resetting the unit didn't resolve it. So you're mileage may vary.

This tiny microcontroller is great for small projects. Actually, it's quite powerful for what it is and has plenty of I/O pins. My son uses it for Star Wars props and Cosplay. It's great for wearables, controlling LEDs, and just about anything an Arduino can do but just more. The setup can be a little confusing at first, but the documentation on the SeedStudio site is really good. It will walk you through with setting up the Arduino IDE or setting up Circuit Python, since the setup is very different from each other. I've programmed this little microcontroller with both the Arduino IDE and with Circuit Python. Circuit Python might be more beginner friendly. I really like that it has USB Type-C connector because then I can use the same cable as my Mobile Phones. It's annoying to have so many different cables around. One thing to make note is that these microcontrollers are not 5v tolerant. Yes, you can power it with 5 volts, but the inputs and outputs are 3.3 volts. The one thing I wish it had was a reset button, but it's so small I'm sure it would be impossible to fit. You can add a reset button because there are soldering pads for it, but it doesn't have one on the board it self. So, if you are making wearables this would be great. Actually, you can use it to control servos, led light strips, and a ton more. It even has a DAC so you can technically make it produce sound too!

Very good Stamp sized controller. Best in the series, the ESP32S3 chip is one of the best performers. My application involved an I2S interface to a microphone and four RMT interface outputs to SM2812B leds. Issue #1: The 3.3v regulator on this board has fluctuating output and I need to run my microphone on a separate regulator or I can 'hear' the CPU processing as noise in the microphone. Other arduino boards do not have this issue. The oscilloscope revealed that this chip makes it's power rails rather noisy! Issue #2: Pin 7 (GPIO43) has a part on it that makes the bandwidth poor. This pin isn't usable for high bandwidth control. It's a design choice on their part. Darn good board. Five stars.

Great price and fast shipping! Will use again.

This was an intriguing little thing. It powered up and did it's version of the Arduino "Blink" program. I didn't find it as easy and intuitive to get installed and functioning as I did with the Arduino family. I was quite disapointed because in it's tiny package it is faster and has more memory. Having every pin able to act as an Interrupt give a programmer lots of options when faced with intricate program logic. I guess I missed a step in getting installed because It no longer functions. I find to way to attempt to breathe life into it. I would attempt it again but I have pleanty of things to keep me busy as it is.

Received this XIAO yesterday. IT IS TINY!! Plugged it into the USB port and brought up the Arduino IDE 2.3.7. You will need to install a new package in the Arduino IDE. I found that you will need to close the IDE and restart it for things to work after installation. To quickly test, I uploaded an IDE Example called AnalogInOutSerial from the Examples list under File. Worked right off!! It is markedly faster than the Arduino Leonardo I got a weeks ago. I was pleasantly surprised at its functionality when compared to the Arduino Nano.

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’ve always been impressed with the products from Seeed Studio. They just work, and I really appreciate the content the have on their website for helpful guides and tutorials. The soldering on the pins was well done and it came nicely packaged.