New microcontrollers from Microchip use a single pin for programming the so called UPDI pin. This means, simpler programming interface yet, a new programmer is needed. Since its easy and cheap to get your hands on an Arduino Nano or most likely you already have one or more lying around, this is a simple and cheap adapter board turning an Arduino Nano to a UPDI programmer.

Simply program your Arduino Nano with JTAG2UPDI sketch, attach to the adapter and select the switch position (red led on if target has no 4.7k resistor to its UPDI pin, blue if it does) ... and upload your sketch ! Simple, easy and very low cost solution ... The adapter is designed to make use of a standard USB cable to connect to the target provided its D+ pin is used as UPDI connection. But also has UPDI/GND/5V pins broken out and ready to connect to any target.