Review on 🔌 Smallest Arduino Microcontroller Seeeduino XIAO - SAMD21 Based, Enriched Interfaces, Fully Compatible with Arduino IDE, Ideal for Projects Requiring Arduino Micro, 1pc by Prince Burr

I bought three of these because they were very small and not too expensive. Because they were smaller than the Nano and faster, they looked attractive. I intended to design a fire alarm system around them, not complicated at all. But I found a few limitations of this chip.1. There is no reset button and the solder pads are very close together. I'm fine with 0.1 inch even 2mm but that's too doubtful.2. Frequent loss of USB communication with IDE. It wouldn't be so bad if there was a reset button, but see above.3. The lack of EEPROM and Flash memory means that all stored parameters must be overwritten with every code update.4. Less than 3mA. Source or drain current on I/O pins. Even lighting an LED requires a transistor.5. There is no external ARef. When using the ADC, I found that the internal AREF, which I had set at 2.5V, seemed to be drifting. It may be obtained from the supply voltage via a voltage divider.6. Limited Documentation. Even when I looked for the official manufacturer specification for this chip, I couldn't find out much about the ADC. It can be fine for fairly simple projects, but it's too difficult to work around its flaws to use for anything that has an important function.