I decided to make a board for trying out the new AVR DA and DB series chips. I decided to design it for the though-hole versions as the new chips still have a bit of hardware errata and thus make it easy to swap in newer revisions as they come out with fewer hardware errata. All one needs from a programmer is a USB to serial adapter. I've used CH340's and FTDI232's. An important thing to note is that it of this writing, uploading code can be a bit finicky; not all USB to serial adapters work, I had to use a 2K resistor between the RX and TX pins to make the CH340 happy. For the software to upload code, I"m using pyupdi which can be found here.