Thea Flowers of Winterbloom writes in detail about using the brown-out detector on the MicroChip ATSAMD21 microcontroller to make hardware be more reliable and resilient to flaky power. The SAMD21 is used in Winterbloom’s Castor & Pollux synthesizer module, and also in the CircuitPython-powered Big Honking Button.

Using the SAM D21’s brown-out detector

Over the past year, I’ve been getting more and more acquainted with the SAM D21 32-bit ARM-Cortex M0+ microcontroller. It’s a lovely little chip and you can find it all over the place – notably in the Arduino Zero and several of Adafruit’s M0 boards. I’ve written several articles about various aspects of the SAM D21 and I’ve even shipped two products that use it as their brain.

In this post, I’ll cover the basics of the SAM D21’s brown-out detector, why it’s not just useful but critical, and how it can help you make your SAM D21-based project more reliable and resilient. Even if you think your project will never be subjected to a brown-out event, I promise it’s worth your time to learn about the brown-out detector and how it can save you from all kinds of unexpected behavior.

From https://blog.thea.codes/sam-d21-brown-out-detector/