Seeeduino XIAO - Arduino Microcontroller - SAMD21 Cortex M0+

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.

Very satisfied with the purchase, all 3 SAMD21 board tested and confirmed working. I will be able to prototype easily with these spare boards

Ich bin wirklich vollkommen begeistert von diesem kleinen Board. Es ist inzwischen schon das zweite Dreier‑Set, das ich bestellt habe, weil der XIAO einfach zuverlässig funktioniert und sich super in die Arduino‑IDE einbinden lässt. Ich habe ihn mittlerweile in mehreren Projekten verbaut, und mit dem passenden Expansion Board wird er noch vielseitiger: kleines Display, ein Taster – mehr braucht es manchmal gar nicht. Für meine Frau habe ich damit einen einfachen Teetimer gebaut, der total unkompliziert zu bedienen ist und jeden Tag im Einsatz ist.

One of the 3 isn't work. It refuses to let me upload a program. Even rebooting doesn't help

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.