The Desk of Ladyada - Feather M4 Redux: Pink PCB Adalogger + STEMMA QT update

It is starting to get a bit chilly out, with beautiful fall weather. We’ve even switched from iced to hot coffees! We decided this week to take a look again at our favvy Feather, the M4 Express. It’s a good dev board, but there’s improvements we can make given the years of experience we’ve had with designing Feathers. First up we swapped the Micro USB to USB C. We bumped the 2MB flash to 8MB, and added a STEMMA QT plug at the end. We also put a MicroSD card slot on the bottom, like our STM32 Feather. Finally, we made a few low-power-friendly improvements! We’ll take a tour at the design in this stream The Great Search - 32 KHz RTC Crystals We did an earlier Great Search on oscillators, but this week we’re specifically looking at 32kHz ’real time clock/counter’ crystals. These are often used in microcontrollers as input to a PLL to generate a higher frequency internal clock that is more precise than an RC oscillator. Even tho these are not ’semiconductors’ they’ve been q