The UPDI acronym stands for Unified Program and Debug Interface, but this device is compact and adorable enough to earn the nickname "Unusually Playful Device Interfacer", and we might just give it a congratulatory pat on the head when it performs well. Its design allows for effortless programming of modern ATtiny chips, with features such as 3V or 5V power and logic select, power and transmit indicator LEDs, and a convenient cable for connecting to a breadboard.

Our recent usage of ATtiny816, ATtiny817, and ATtiny1616 microchips for our seesaw boards has led us to frequently utilize the CP2102-based breakout with a 1K resistor between the RX and TX pins for programming. However, we desired a more sophisticated and efficient programmer for these tasks.

This UPDI Friend makes programming such chips very easy:

• Select between 3V or 5V power and logic - the 3V regulator can source up to 500mA so it can run even big projects. 
• CH340E USB Serial converter chip with cross-platform drivers
• 1K Loop-back Resistor between RX and TX
• USB Type C for data and power connection to any computer
• JST SH cable included for quick plugging into a breadboard - you can get another or with here.
• 0.1" spaced breakout holes for custom connections.
• Green power OK LED
• Red serial activity LED
• Inspired by this  from !

We use Arduino IDE with the installed, simply select "Serial UPDI" as the programmer type, we use 230Kbps but 56Kbps is also good.